diff mbox

[1/7] enhance -Wformat to detect quoting problems (PR 80280 et al.)

Message ID 8dc099ad-8a91-937a-3969-1ba0893a0b20@gmail.com
State New
Headers show

Commit Message

Martin Sebor May 3, 2017, 2:36 a.m. UTC 
In bug 80280 - Missing closing quote (%>) c/semantics.c and
c/c-typeck.c, a translator points out one of a number of kinds
of cosmetic problems that tend to come up late in development,
during translation of GCC messages.  Other, arguably more minor,
kinds of issues are caused by forgetting to use proper quoting
when referencing tree nodes, such as %D or %T.

To help avoid these kinds of bugs, the attached patch enhances
the -Wformat checker to detect these common quoting issues and
report them as warnings.

The remaining six patches in the series correct the problems
highlighted by the warning and get GCC to bootstrap and pass
regression tests on x86_64.  I suspect additional fixes will
be needed to get GCC to bootstrap on other targets.  I'll do
powerpc64le next but besides a general review I'm looking for
suggestions how to do the same cleanup on all the other targets
with the least disruption. (E.g., if there's a way to roll out
a warning one target at a time I could introduce it under
a suboption of -Wformat and enable the subobption with -Werror
only on the targets that have already been verified.)

Thanks
Martin

Comments

Joseph Myers May 3, 2017, 3:53 p.m. UTC | #1 
On Tue, 2 May 2017, Martin Sebor wrote:

> In bug 80280 - Missing closing quote (%>) c/semantics.c and
> c/c-typeck.c, a translator points out one of a number of kinds
> of cosmetic problems that tend to come up late in development,
> during translation of GCC messages.  Other, arguably more minor,
> kinds of issues are caused by forgetting to use proper quoting
> when referencing tree nodes, such as %D or %T.
> 
> To help avoid these kinds of bugs, the attached patch enhances
> the -Wformat checker to detect these common quoting issues and
> report them as warnings.

As I see it, there are four kinds of format specifiers in this context:

* Specifiers that have no special interaction with quoting and may be used 
either quoted or unquoted.  For example, %d, %s and %E.  (%E is only of 
that kind when used for expressions - when hopefully it should only be 
used for simple expressions such as constants.  Uses for identifiers 
should be quoted; cases where there can be complex expressions should be 
replaced by use of location ranges.  Ideally identifiers and expressions 
should have different formats, so these cases can be distinguished and so 
identifiers can end up with a static type other than "tree".)

* Specifiers that should be quoted.  For example, %D.

* Specifiers that open quoting (%<).

* Specifiers that close quoting (%>).

(In addition, the q flag serves to quote the specifier it's applied to.)

> The remaining six patches in the series correct the problems
> highlighted by the warning and get GCC to bootstrap and pass
> regression tests on x86_64.  I suspect additional fixes will
> be needed to get GCC to bootstrap on other targets.  I'll do
> powerpc64le next but besides a general review I'm looking for
> suggestions how to do the same cleanup on all the other targets
> with the least disruption. (E.g., if there's a way to roll out
> a warning one target at a time I could introduce it under
> a suboption of -Wformat and enable the subobption with -Werror
> only on the targets that have already been verified.)

Use contrib/config-list.mk, with a native compiler with this patch in the 
PATH, to test building compilers for many configurations.  (No doubt 
you'll also find existing build issues, which may or may not be filed in 
Bugzilla.)

> +      /* Diagnose nested or unmatched quoting directives such as GCC's
> +	 "%<...%<" and "%>...%>".  As a special case, a directive can
> +	 be considered to both begin and end quoting (e.g., GCC's %E).
> +	 Such a directive is recognized but not diagosed.  */

I don't think it makes conceptual sense to consider %E to both begin and 
end quoting.  I'd expect %E to have exactly the same begin_quote and 
end_quote (or whatever) data as %d and %s, because it has the same 
properties (may be used quoted or unquoted).

> diff --git a/gcc/c-family/c-format.h b/gcc/c-family/c-format.h
> index 13ca8ea..8932861 100644
> --- a/gcc/c-family/c-format.h
> +++ b/gcc/c-family/c-format.h
> @@ -132,6 +132,11 @@ struct format_type_detail
>  struct format_char_info
>  {
>    const char *format_chars;
> +  /* Strings of FORMAT_CHARS characters that begin and end quoting,
> +     respectively, and pairs of which should be matched in the same
> +     format string.  NULL when no such pairs exist.  */
> +  const char *quote_begin_chars;
> +  const char *quote_end_chars;

I don't think this comment is sufficiently detailed to make it obvious 
what should appear in each field for each of the four kinds of format 
specifiers I enumerated.  The best I can reverse-engineer from the code 
is: NULL for specifiers that may be used either quoted or unquoted *or* 
listing those specifiers in both quote_begin_chars and quote_end_chars 
(but I think the option of listing them in both should be removed as 
conceptually wrong); if the character is an opening or closing quote, list 
it in the appropriate one; if it must be used quoted, but isn't a quote 
itself, both strings must be non-NULL but it must not be listed in either.

Whether that's right or wrong, the comment needs to make the rules clear.
diff mbox

Patch

PR translation/80280 - Missing closing quote (%>) c/semantics.c and c/c-typeck.c

gcc/c-family/ChangeLog:

	PR translation/80280
	* c-format.h (struct format_char_info): Add new members.
	(struct format_flag_spec): Likweise.
	* c-format.c (printf_flag_specs, asm_fprintf_flag_spec): Initialize
	them.
	(gcc_diag_flag_specs, scanf_flag_specs, strftime_flag_specs,
	strfmon_flag_specs, print_char_table, asm_fprintf_char_table): Likewise.
	(gcc_diag_char_table, gcc_cdiag_char_table, gcc_tdiag_char_table):
	Likewise.
	(gcc_cxxdiag_char_table, gcc_gfc_char_table, scan_char_table): Ditto.
	(time_char_table, monetary_char_table): Same here.
	(flag_chars_t::validate): Add argument and handle bad quoting.
	(check_format_info_main): Handle quoting problems.

gcc/testsuite/ChangeLog:

	PR translation/80280
	* gcc.dg/format/ext-9.c: New test.

diff --git a/gcc/c-family/c-format.c b/gcc/c-family/c-format.c
index 400eb66..a7a8d4e 100644
--- a/gcc/c-family/c-format.c
+++ b/gcc/c-family/c-format.c
@@ -492,17 +492,17 @@  static const format_length_info gcc_gfc_length_specs[] =
 
 static const format_flag_spec printf_flag_specs[] =
 {
-  { ' ',  0, 0, N_("' ' flag"),        N_("the ' ' printf flag"),              STD_C89 },
-  { '+',  0, 0, N_("'+' flag"),        N_("the '+' printf flag"),              STD_C89 },
-  { '#',  0, 0, N_("'#' flag"),        N_("the '#' printf flag"),              STD_C89 },
-  { '0',  0, 0, N_("'0' flag"),        N_("the '0' printf flag"),              STD_C89 },
-  { '-',  0, 0, N_("'-' flag"),        N_("the '-' printf flag"),              STD_C89 },
-  { '\'', 0, 0, N_("''' flag"),        N_("the ''' printf flag"),              STD_EXT },
-  { 'I',  0, 0, N_("'I' flag"),        N_("the 'I' printf flag"),              STD_EXT },
-  { 'w',  0, 0, N_("field width"),     N_("field width in printf format"),     STD_C89 },
-  { 'p',  0, 0, N_("precision"),       N_("precision in printf format"),       STD_C89 },
-  { 'L',  0, 0, N_("length modifier"), N_("length modifier in printf format"), STD_C89 },
-  { 0, 0, 0, NULL, NULL, STD_C89 }
+  { ' ',  0, 0, 0, N_("' ' flag"),        N_("the ' ' printf flag"),              STD_C89 },
+  { '+',  0, 0, 0, N_("'+' flag"),        N_("the '+' printf flag"),              STD_C89 },
+  { '#',  0, 0, 0, N_("'#' flag"),        N_("the '#' printf flag"),              STD_C89 },
+  { '0',  0, 0, 0, N_("'0' flag"),        N_("the '0' printf flag"),              STD_C89 },
+  { '-',  0, 0, 0, N_("'-' flag"),        N_("the '-' printf flag"),              STD_C89 },
+  { '\'', 0, 0, 0, N_("''' flag"),        N_("the ''' printf flag"),              STD_EXT },
+  { 'I',  0, 0, 0, N_("'I' flag"),        N_("the 'I' printf flag"),              STD_EXT },
+  { 'w',  0, 0, 0, N_("field width"),     N_("field width in printf format"),     STD_C89 },
+  { 'p',  0, 0, 0, N_("precision"),       N_("precision in printf format"),       STD_C89 },
+  { 'L',  0, 0, 0, N_("length modifier"), N_("length modifier in printf format"), STD_C89 },
+  { 0, 0, 0, 0, NULL, NULL, STD_C89 }
 };
 
 
@@ -516,15 +516,15 @@  static const format_flag_pair printf_flag_pairs[] =
 
 static const format_flag_spec asm_fprintf_flag_specs[] =
 {
-  { ' ',  0, 0, N_("' ' flag"),        N_("the ' ' printf flag"),              STD_C89 },
-  { '+',  0, 0, N_("'+' flag"),        N_("the '+' printf flag"),              STD_C89 },
-  { '#',  0, 0, N_("'#' flag"),        N_("the '#' printf flag"),              STD_C89 },
-  { '0',  0, 0, N_("'0' flag"),        N_("the '0' printf flag"),              STD_C89 },
-  { '-',  0, 0, N_("'-' flag"),        N_("the '-' printf flag"),              STD_C89 },
-  { 'w',  0, 0, N_("field width"),     N_("field width in printf format"),     STD_C89 },
-  { 'p',  0, 0, N_("precision"),       N_("precision in printf format"),       STD_C89 },
-  { 'L',  0, 0, N_("length modifier"), N_("length modifier in printf format"), STD_C89 },
-  { 0, 0, 0, NULL, NULL, STD_C89 }
+  { ' ',  0, 0, 0, N_("' ' flag"),        N_("the ' ' printf flag"),              STD_C89 },
+  { '+',  0, 0, 0, N_("'+' flag"),        N_("the '+' printf flag"),              STD_C89 },
+  { '#',  0, 0, 0, N_("'#' flag"),        N_("the '#' printf flag"),              STD_C89 },
+  { '0',  0, 0, 0, N_("'0' flag"),        N_("the '0' printf flag"),              STD_C89 },
+  { '-',  0, 0, 0, N_("'-' flag"),        N_("the '-' printf flag"),              STD_C89 },
+  { 'w',  0, 0, 0, N_("field width"),     N_("field width in printf format"),     STD_C89 },
+  { 'p',  0, 0, 0, N_("precision"),       N_("precision in printf format"),       STD_C89 },
+  { 'L',  0, 0, 0, N_("length modifier"), N_("length modifier in printf format"), STD_C89 },
+  { 0, 0, 0, 0, NULL, NULL, STD_C89 }
 };
 
 static const format_flag_pair asm_fprintf_flag_pairs[] =
@@ -547,12 +547,12 @@  static const format_flag_pair gcc_diag_flag_pairs[] =
 
 static const format_flag_spec gcc_diag_flag_specs[] =
 {
-  { '+',  0, 0, N_("'+' flag"),        N_("the '+' printf flag"),              STD_C89 },
-  { '#',  0, 0, N_("'#' flag"),        N_("the '#' printf flag"),              STD_C89 },
-  { 'q',  0, 0, N_("'q' flag"),        N_("the 'q' diagnostic flag"),          STD_C89 },
-  { 'p',  0, 0, N_("precision"),       N_("precision in printf format"),       STD_C89 },
-  { 'L',  0, 0, N_("length modifier"), N_("length modifier in printf format"), STD_C89 },
-  { 0, 0, 0, NULL, NULL, STD_C89 }
+  { '+',  0, 0, 0, N_("'+' flag"),        N_("the '+' printf flag"),              STD_C89 },
+  { '#',  0, 0, 0, N_("'#' flag"),        N_("the '#' printf flag"),              STD_C89 },
+  { 'q',  0, 0, 1, N_("'q' flag"),        N_("the 'q' diagnostic flag"),          STD_C89 },
+  { 'p',  0, 0, 0, N_("precision"),       N_("precision in printf format"),       STD_C89 },
+  { 'L',  0, 0, 0, N_("length modifier"), N_("length modifier in printf format"), STD_C89 },
+  { 0, 0, 0, 0, NULL, NULL, STD_C89 }
 };
 
 #define gcc_tdiag_flag_specs gcc_diag_flag_specs
@@ -562,14 +562,14 @@  static const format_flag_spec gcc_diag_flag_specs[] =
 
 static const format_flag_spec scanf_flag_specs[] =
 {
-  { '*',  0, 0, N_("assignment suppression"), N_("the assignment suppression scanf feature"), STD_C89 },
-  { 'a',  0, 0, N_("'a' flag"),               N_("the 'a' scanf flag"),                       STD_EXT },
-  { 'm',  0, 0, N_("'m' flag"),               N_("the 'm' scanf flag"),                       STD_EXT },
-  { 'w',  0, 0, N_("field width"),            N_("field width in scanf format"),              STD_C89 },
-  { 'L',  0, 0, N_("length modifier"),        N_("length modifier in scanf format"),          STD_C89 },
-  { '\'', 0, 0, N_("''' flag"),               N_("the ''' scanf flag"),                       STD_EXT },
-  { 'I',  0, 0, N_("'I' flag"),               N_("the 'I' scanf flag"),                       STD_EXT },
-  { 0, 0, 0, NULL, NULL, STD_C89 }
+  { '*',  0, 0, 0, N_("assignment suppression"), N_("the assignment suppression scanf feature"), STD_C89 },
+  { 'a',  0, 0, 0, N_("'a' flag"),               N_("the 'a' scanf flag"),                       STD_EXT },
+  { 'm',  0, 0, 0, N_("'m' flag"),               N_("the 'm' scanf flag"),                       STD_EXT },
+  { 'w',  0, 0, 0, N_("field width"),            N_("field width in scanf format"),              STD_C89 },
+  { 'L',  0, 0, 0, N_("length modifier"),        N_("length modifier in scanf format"),          STD_C89 },
+  { '\'', 0, 0, 0, N_("''' flag"),               N_("the ''' scanf flag"),                       STD_EXT },
+  { 'I',  0, 0, 0, N_("'I' flag"),               N_("the 'I' scanf flag"),                       STD_EXT },
+  { 0, 0, 0, 0, NULL, NULL, STD_C89 }
 };
 
 
@@ -583,16 +583,16 @@  static const format_flag_pair scanf_flag_pairs[] =
 
 static const format_flag_spec strftime_flag_specs[] =
 {
-  { '_', 0,   0, N_("'_' flag"),     N_("the '_' strftime flag"),          STD_EXT },
-  { '-', 0,   0, N_("'-' flag"),     N_("the '-' strftime flag"),          STD_EXT },
-  { '0', 0,   0, N_("'0' flag"),     N_("the '0' strftime flag"),          STD_EXT },
-  { '^', 0,   0, N_("'^' flag"),     N_("the '^' strftime flag"),          STD_EXT },
-  { '#', 0,   0, N_("'#' flag"),     N_("the '#' strftime flag"),          STD_EXT },
-  { 'w', 0,   0, N_("field width"),  N_("field width in strftime format"), STD_EXT },
-  { 'E', 0,   0, N_("'E' modifier"), N_("the 'E' strftime modifier"),      STD_C99 },
-  { 'O', 0,   0, N_("'O' modifier"), N_("the 'O' strftime modifier"),      STD_C99 },
-  { 'O', 'o', 0, NULL,               N_("the 'O' modifier"),               STD_EXT },
-  { 0, 0, 0, NULL, NULL, STD_C89 }
+  { '_', 0,   0, 0, N_("'_' flag"),     N_("the '_' strftime flag"),          STD_EXT },
+  { '-', 0,   0, 0, N_("'-' flag"),     N_("the '-' strftime flag"),          STD_EXT },
+  { '0', 0,   0, 0, N_("'0' flag"),     N_("the '0' strftime flag"),          STD_EXT },
+  { '^', 0,   0, 0, N_("'^' flag"),     N_("the '^' strftime flag"),          STD_EXT },
+  { '#', 0,   0, 0, N_("'#' flag"),     N_("the '#' strftime flag"),          STD_EXT },
+  { 'w', 0,   0, 0, N_("field width"),  N_("field width in strftime format"), STD_EXT },
+  { 'E', 0,   0, 0, N_("'E' modifier"), N_("the 'E' strftime modifier"),      STD_C99 },
+  { 'O', 0,   0, 0, N_("'O' modifier"), N_("the 'O' strftime modifier"),      STD_C99 },
+  { 'O', 'o', 0, 0, NULL,               N_("the 'O' modifier"),               STD_EXT },
+  { 0, 0, 0, 0, NULL, NULL, STD_C89 }
 };
 
 
@@ -609,17 +609,17 @@  static const format_flag_pair strftime_flag_pairs[] =
 
 static const format_flag_spec strfmon_flag_specs[] =
 {
-  { '=',  0, 1, N_("fill character"),  N_("fill character in strfmon format"),  STD_C89 },
-  { '^',  0, 0, N_("'^' flag"),        N_("the '^' strfmon flag"),              STD_C89 },
-  { '+',  0, 0, N_("'+' flag"),        N_("the '+' strfmon flag"),              STD_C89 },
-  { '(',  0, 0, N_("'(' flag"),        N_("the '(' strfmon flag"),              STD_C89 },
-  { '!',  0, 0, N_("'!' flag"),        N_("the '!' strfmon flag"),              STD_C89 },
-  { '-',  0, 0, N_("'-' flag"),        N_("the '-' strfmon flag"),              STD_C89 },
-  { 'w',  0, 0, N_("field width"),     N_("field width in strfmon format"),     STD_C89 },
-  { '#',  0, 0, N_("left precision"),  N_("left precision in strfmon format"),  STD_C89 },
-  { 'p',  0, 0, N_("right precision"), N_("right precision in strfmon format"), STD_C89 },
-  { 'L',  0, 0, N_("length modifier"), N_("length modifier in strfmon format"), STD_C89 },
-  { 0, 0, 0, NULL, NULL, STD_C89 }
+  { '=',  0, 1, 0, N_("fill character"),  N_("fill character in strfmon format"),  STD_C89 },
+  { '^',  0, 0, 0, N_("'^' flag"),        N_("the '^' strfmon flag"),              STD_C89 },
+  { '+',  0, 0, 0, N_("'+' flag"),        N_("the '+' strfmon flag"),              STD_C89 },
+  { '(',  0, 0, 0, N_("'(' flag"),        N_("the '(' strfmon flag"),              STD_C89 },
+  { '!',  0, 0, 0, N_("'!' flag"),        N_("the '!' strfmon flag"),              STD_C89 },
+  { '-',  0, 0, 0, N_("'-' flag"),        N_("the '-' strfmon flag"),              STD_C89 },
+  { 'w',  0, 0, 0, N_("field width"),     N_("field width in strfmon format"),     STD_C89 },
+  { '#',  0, 0, 0, N_("left precision"),  N_("left precision in strfmon format"),  STD_C89 },
+  { 'p',  0, 0, 0, N_("right precision"), N_("right precision in strfmon format"), STD_C89 },
+  { 'L',  0, 0, 0, N_("length modifier"), N_("length modifier in strfmon format"), STD_C89 },
+  { 0, 0, 0, 0, NULL, NULL, STD_C89 }
 };
 
 static const format_flag_pair strfmon_flag_pairs[] =
@@ -632,214 +632,214 @@  static const format_flag_pair strfmon_flag_pairs[] =
 static const format_char_info print_char_table[] =
 {
   /* C89 conversion specifiers.  */
-  { "di",  0, STD_C89, { T89_I,   T99_SC,  T89_S,   T89_L,   T9L_LL,  TEX_LL,  T99_SST, T99_PD,  T99_IM,  BADLEN,  BADLEN,  BADLEN  }, "-wp0 +'I",  "i",  NULL },
-  { "oxX", 0, STD_C89, { T89_UI,  T99_UC,  T89_US,  T89_UL,  T9L_ULL, TEX_ULL, T99_ST,  T99_UPD, T99_UIM, BADLEN,  BADLEN,  BADLEN }, "-wp0#",     "i",  NULL },
-  { "u",   0, STD_C89, { T89_UI,  T99_UC,  T89_US,  T89_UL,  T9L_ULL, TEX_ULL, T99_ST,  T99_UPD, T99_UIM, BADLEN,  BADLEN,  BADLEN }, "-wp0'I",    "i",  NULL },
-  { "fgG", 0, STD_C89, { T89_D,   BADLEN,  BADLEN,  T99_D,   BADLEN,  T89_LD,  BADLEN,  BADLEN,  BADLEN,  TEX_D32, TEX_D64, TEX_D128 }, "-wp0 +#'I", "",   NULL },
-  { "eE",  0, STD_C89, { T89_D,   BADLEN,  BADLEN,  T99_D,   BADLEN,  T89_LD,  BADLEN,  BADLEN,  BADLEN,  TEX_D32, TEX_D64, TEX_D128 }, "-wp0 +#I",  "",   NULL },
-  { "c",   0, STD_C89, { T89_I,   BADLEN,  BADLEN,  T94_WI,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "-w",        "",   NULL },
-  { "s",   1, STD_C89, { T89_C,   BADLEN,  BADLEN,  T94_W,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "-wp",       "cR", NULL },
-  { "p",   1, STD_C89, { T89_V,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "-w",        "c",  NULL },
-  { "n",   1, STD_C89, { T89_I,   T99_SC,  T89_S,   T89_L,   T9L_LL,  BADLEN,  T99_SST, T99_PD,  T99_IM,  BADLEN,  BADLEN,  BADLEN }, "",          "W",  NULL },
+  { "di",  NULL, NULL, 0, STD_C89, { T89_I,   T99_SC,  T89_S,   T89_L,   T9L_LL,  TEX_LL,  T99_SST, T99_PD,  T99_IM,  BADLEN,  BADLEN,  BADLEN  }, "-wp0 +'I",  "i",  NULL },
+  { "oxX", NULL, NULL, 0, STD_C89, { T89_UI,  T99_UC,  T89_US,  T89_UL,  T9L_ULL, TEX_ULL, T99_ST,  T99_UPD, T99_UIM, BADLEN,  BADLEN,  BADLEN }, "-wp0#",     "i",  NULL },
+  { "u", NULL, NULL,   0, STD_C89, { T89_UI,  T99_UC,  T89_US,  T89_UL,  T9L_ULL, TEX_ULL, T99_ST,  T99_UPD, T99_UIM, BADLEN,  BADLEN,  BADLEN }, "-wp0'I",    "i",  NULL },
+  { "fgG", NULL, NULL, 0, STD_C89, { T89_D,   BADLEN,  BADLEN,  T99_D,   BADLEN,  T89_LD,  BADLEN,  BADLEN,  BADLEN,  TEX_D32, TEX_D64, TEX_D128 }, "-wp0 +#'I", "",   NULL },
+  { "eE", NULL, NULL,  0, STD_C89, { T89_D,   BADLEN,  BADLEN,  T99_D,   BADLEN,  T89_LD,  BADLEN,  BADLEN,  BADLEN,  TEX_D32, TEX_D64, TEX_D128 }, "-wp0 +#I",  "",   NULL },
+  { "c", NULL, NULL,   0, STD_C89, { T89_I,   BADLEN,  BADLEN,  T94_WI,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "-w",        "",   NULL },
+  { "s", NULL, NULL,   1, STD_C89, { T89_C,   BADLEN,  BADLEN,  T94_W,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "-wp",       "cR", NULL },
+  { "p", NULL, NULL,   1, STD_C89, { T89_V,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "-w",        "c",  NULL },
+  { "n", NULL, NULL,   1, STD_C89, { T89_I,   T99_SC,  T89_S,   T89_L,   T9L_LL,  BADLEN,  T99_SST, T99_PD,  T99_IM,  BADLEN,  BADLEN,  BADLEN }, "",          "W",  NULL },
   /* C99 conversion specifiers.  */
-  { "F",   0, STD_C99, { T99_D,   BADLEN,  BADLEN,  T99_D,   BADLEN,  T99_LD,  BADLEN,  BADLEN,  BADLEN,  TEX_D32, TEX_D64, TEX_D128 }, "-wp0 +#'I", "",   NULL },
-  { "aA",  0, STD_C99, { T99_D,   BADLEN,  BADLEN,  T99_D,   BADLEN,  T99_LD,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "-wp0 +#",   "",   NULL },
+  { "F", NULL, NULL,   0, STD_C99, { T99_D,   BADLEN,  BADLEN,  T99_D,   BADLEN,  T99_LD,  BADLEN,  BADLEN,  BADLEN,  TEX_D32, TEX_D64, TEX_D128 }, "-wp0 +#'I", "",   NULL },
+  { "aA", NULL, NULL,  0, STD_C99, { T99_D,   BADLEN,  BADLEN,  T99_D,   BADLEN,  T99_LD,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "-wp0 +#",   "",   NULL },
   /* X/Open conversion specifiers.  */
-  { "C",   0, STD_EXT, { TEX_WI,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "-w",        "",   NULL },
-  { "S",   1, STD_EXT, { TEX_W,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "-wp",       "R",  NULL },
+  { "C", NULL, NULL,   0, STD_EXT, { TEX_WI,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "-w",        "",   NULL },
+  { "S", NULL, NULL,   1, STD_EXT, { TEX_W,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "-wp",       "R",  NULL },
   /* GNU conversion specifiers.  */
-  { "m",   0, STD_EXT, { T89_V,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "-wp",       "",   NULL },
-  { NULL,  0, STD_C89, NOLENGTHS, NULL, NULL, NULL }
+  { "m", NULL, NULL,   0, STD_EXT, { T89_V,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "-wp",       "",   NULL },
+  { NULL,  NULL, NULL, 0, STD_C89, NOLENGTHS, NULL, NULL, NULL }
 };
 
 static const format_char_info asm_fprintf_char_table[] =
 {
   /* C89 conversion specifiers.  */
-  { "di",  0, STD_C89, { T89_I,   BADLEN,  BADLEN,  T89_L,   T9L_LL,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "-wp0 +",  "i", NULL },
-  { "oxX", 0, STD_C89, { T89_UI,  BADLEN,  BADLEN,  T89_UL,  T9L_ULL, BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "-wp0#",   "i", NULL },
-  { "u",   0, STD_C89, { T89_UI,  BADLEN,  BADLEN,  T89_UL,  T9L_ULL, BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "-wp0",    "i", NULL },
-  { "c",   0, STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "-w",       "", NULL },
-  { "s",   1, STD_C89, { T89_C,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "-wp",    "cR", NULL },
+  { "di", NULL, NULL,  0, STD_C89, { T89_I,   BADLEN,  BADLEN,  T89_L,   T9L_LL,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "-wp0 +",  "i", NULL },
+  { "oxX", NULL, NULL, 0, STD_C89, { T89_UI,  BADLEN,  BADLEN,  T89_UL,  T9L_ULL, BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "-wp0#",   "i", NULL },
+  { "u", NULL, NULL,   0, STD_C89, { T89_UI,  BADLEN,  BADLEN,  T89_UL,  T9L_ULL, BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "-wp0",    "i", NULL },
+  { "c", NULL, NULL,   0, STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "-w",       "", NULL },
+  { "s", NULL, NULL,   1, STD_C89, { T89_C,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "-wp",    "cR", NULL },
 
   /* asm_fprintf conversion specifiers.  */
-  { "O",   0, STD_C89, NOARGUMENTS, "",      "",   NULL },
-  { "R",   0, STD_C89, NOARGUMENTS, "",      "",   NULL },
-  { "I",   0, STD_C89, NOARGUMENTS, "",      "",   NULL },
-  { "L",   0, STD_C89, NOARGUMENTS, "",      "",   NULL },
-  { "U",   0, STD_C89, NOARGUMENTS, "",      "",   NULL },
-  { "r",   0, STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "",  "", NULL },
-  { "@",   0, STD_C89, NOARGUMENTS, "",      "",   NULL },
-  { NULL,  0, STD_C89, NOLENGTHS, NULL, NULL, NULL }
+  { "O", NULL, NULL,   0, STD_C89, NOARGUMENTS, "",      "",   NULL },
+  { "R", NULL, NULL,   0, STD_C89, NOARGUMENTS, "",      "",   NULL },
+  { "I", NULL, NULL,   0, STD_C89, NOARGUMENTS, "",      "",   NULL },
+  { "L", NULL, NULL,   0, STD_C89, NOARGUMENTS, "",      "",   NULL },
+  { "U", NULL, NULL,   0, STD_C89, NOARGUMENTS, "",      "",   NULL },
+  { "r", NULL, NULL,   0, STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "",  "", NULL },
+  { "@", NULL, NULL,   0, STD_C89, NOARGUMENTS, "",      "",   NULL },
+  { NULL, NULL, NULL,  0, STD_C89, NOLENGTHS, NULL, NULL, NULL }
 };
 
 static const format_char_info gcc_diag_char_table[] =
 {
   /* C89 conversion specifiers.  */
-  { "di",  0, STD_C89, { T89_I,   BADLEN,  BADLEN,  T89_L,   T9L_LL,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
-  { "ox",  0, STD_C89, { T89_UI,  BADLEN,  BADLEN,  T89_UL,  T9L_ULL, BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
-  { "u",   0, STD_C89, { T89_UI,  BADLEN,  BADLEN,  T89_UL,  T9L_ULL, BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
-  { "c",   0, STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
-  { "s",   1, STD_C89, { T89_C,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "pq", "cR", NULL },
-  { "p",   1, STD_C89, { T89_V,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "c",  NULL },
+  { "di", NULL, NULL,  0, STD_C89, { T89_I,   BADLEN,  BADLEN,  T89_L,   T9L_LL,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
+  { "ox", NULL, NULL,  0, STD_C89, { T89_UI,  BADLEN,  BADLEN,  T89_UL,  T9L_ULL, BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
+  { "u", NULL, NULL,   0, STD_C89, { T89_UI,  BADLEN,  BADLEN,  T89_UL,  T9L_ULL, BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
+  { "c", NULL, NULL,   0, STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
+  { "s", NULL, NULL,   1, STD_C89, { T89_C,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "pq", "cR", NULL },
+  { "p", NULL, NULL,   1, STD_C89, { T89_V,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "c",  NULL },
 
   /* Custom conversion specifiers.  */
 
   /* These will require a "tree" at runtime.  */
-  { "K",   0, STD_C89, { T89_V,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",    "",   NULL },
+  { "K", NULL, NULL,   0, STD_C89, { T89_V,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",    "",   NULL },
 
-  { "r",   1, STD_C89, { T89_C,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "",    "cR",   NULL },
-  { "<>'R",0, STD_C89, NOARGUMENTS, "",      "",   NULL },
-  { "m",   0, STD_C89, NOARGUMENTS, "q",     "",   NULL },
-  { NULL,  0, STD_C89, NOLENGTHS, NULL, NULL, NULL }
+  { "r", NULL, NULL,   1, STD_C89, { T89_C,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "",    "cR",   NULL },
+  { "<>'R","<'R", ">'R", 0, STD_C89, NOARGUMENTS, "",      "",   NULL },
+  { "m", NULL, NULL,   0, STD_C89, NOARGUMENTS, "q",     "",   NULL },
+  { NULL, NULL, NULL,  0, STD_C89, NOLENGTHS, NULL, NULL, NULL }
 };
 
 static const format_char_info gcc_tdiag_char_table[] =
 {
   /* C89 conversion specifiers.  */
-  { "di",  0, STD_C89, { T89_I,   BADLEN,  BADLEN,  T89_L,   T9L_LL,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
-  { "ox",  0, STD_C89, { T89_UI,  BADLEN,  BADLEN,  T89_UL,  T9L_ULL, BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
-  { "u",   0, STD_C89, { T89_UI,  BADLEN,  BADLEN,  T89_UL,  T9L_ULL, BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
-  { "c",   0, STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
-  { "s",   1, STD_C89, { T89_C,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "pq", "cR", NULL },
-  { "p",   1, STD_C89, { T89_V,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "c",  NULL },
+  { "di", NULL, NULL,  0, STD_C89, { T89_I,   BADLEN,  BADLEN,  T89_L,   T9L_LL,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
+  { "ox", NULL, NULL,  0, STD_C89, { T89_UI,  BADLEN,  BADLEN,  T89_UL,  T9L_ULL, BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
+  { "u", NULL, NULL,   0, STD_C89, { T89_UI,  BADLEN,  BADLEN,  T89_UL,  T9L_ULL, BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
+  { "c", NULL, NULL,   0, STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
+  { "s", NULL, NULL,   1, STD_C89, { T89_C,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "pq", "cR", NULL },
+  { "p", NULL, NULL,   1, STD_C89, { T89_V,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "c",  NULL },
 
   /* Custom conversion specifiers.  */
 
   /* These will require a "tree" at runtime.  */
-  { "DFKTEV", 0, STD_C89, { T89_V,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q+", "",   NULL },
+  { "DFKTEV", "EK", "EK", 0, STD_C89, { T89_V,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q+", "",   NULL },
 
-  { "v",   0, STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q#",  "",   NULL },
+  { "v", NULL, NULL,   0, STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q#",  "",   NULL },
 
-  { "r",   1, STD_C89, { T89_C,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "",    "cR",   NULL },
-  { "<>'R",0, STD_C89, NOARGUMENTS, "",      "",   NULL },
-  { "m",   0, STD_C89, NOARGUMENTS, "q",     "",   NULL },
-  { "Z",   1, STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "",    "", &gcc_tdiag_char_table[0] },
-  { NULL,  0, STD_C89, NOLENGTHS, NULL, NULL, NULL }
+  { "r", NULL, NULL,   1, STD_C89, { T89_C,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "",    "cR",   NULL },
+  { "<>'R", "<'R", ">'R", 0, STD_C89, NOARGUMENTS, "",      "",   NULL },
+  { "m", NULL, NULL,   0, STD_C89, NOARGUMENTS, "q",     "",   NULL },
+  { "Z", NULL, NULL,   1, STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "",    "", &gcc_tdiag_char_table[0] },
+  { NULL, NULL, NULL, 0, STD_C89, NOLENGTHS, NULL, NULL, NULL }
 };
 
 static const format_char_info gcc_cdiag_char_table[] =
 {
   /* C89 conversion specifiers.  */
-  { "di",  0, STD_C89, { T89_I,   BADLEN,  BADLEN,  T89_L,   T9L_LL,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
-  { "ox",  0, STD_C89, { T89_UI,  BADLEN,  BADLEN,  T89_UL,  T9L_ULL, BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
-  { "u",   0, STD_C89, { T89_UI,  BADLEN,  BADLEN,  T89_UL,  T9L_ULL, BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
-  { "c",   0, STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
-  { "s",   1, STD_C89, { T89_C,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "pq", "cR", NULL },
-  { "p",   1, STD_C89, { T89_V,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "c",  NULL },
+  { "di", NULL, NULL,  0, STD_C89, { T89_I,   BADLEN,  BADLEN,  T89_L,   T9L_LL,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
+  { "ox", NULL, NULL,  0, STD_C89, { T89_UI,  BADLEN,  BADLEN,  T89_UL,  T9L_ULL, BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
+  { "u", NULL, NULL,   0, STD_C89, { T89_UI,  BADLEN,  BADLEN,  T89_UL,  T9L_ULL, BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
+  { "c", NULL, NULL,   0, STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
+  { "s", NULL, NULL,   1, STD_C89, { T89_C,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "pq", "cR", NULL },
+  { "p", NULL, NULL,   1, STD_C89, { T89_V,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "c",  NULL },
 
   /* Custom conversion specifiers.  */
 
   /* These will require a "tree" at runtime.  */
-  { "DEFKTV", 0, STD_C89, { T89_V,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q+", "",   NULL },
+  { "DEFKTV", "EK", "EK", 0, STD_C89, { T89_V,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q+", "",   NULL },
 
-  { "v",   0, STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q#",  "",   NULL },
+  { "v", NULL, NULL,   0, STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q#",  "",   NULL },
 
-  { "r",   1, STD_C89, { T89_C,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "",    "cR",   NULL },
-  { "<>'R",0, STD_C89, NOARGUMENTS, "",      "",   NULL },
-  { "m",   0, STD_C89, NOARGUMENTS, "q",     "",   NULL },
-  { "Z",   1, STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "",    "", &gcc_tdiag_char_table[0] },
-  { NULL,  0, STD_C89, NOLENGTHS, NULL, NULL, NULL }
+  { "r", NULL, NULL,   1, STD_C89, { T89_C,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "",    "cR",   NULL },
+  { "<>'R", "<'R", ">'R", 0, STD_C89, NOARGUMENTS, "",      "",   NULL },
+  { "m", NULL, NULL,   0, STD_C89, NOARGUMENTS, "q",     "",   NULL },
+  { "Z", NULL, NULL,   1, STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "",    "", &gcc_tdiag_char_table[0] },
+  { NULL, NULL, NULL, 0, STD_C89, NOLENGTHS, NULL, NULL, NULL }
 };
 
 static const format_char_info gcc_cxxdiag_char_table[] =
 {
   /* C89 conversion specifiers.  */
-  { "di",  0, STD_C89, { T89_I,   BADLEN,  BADLEN,  T89_L,   T9L_LL,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
-  { "ox",  0, STD_C89, { T89_UI,  BADLEN,  BADLEN,  T89_UL,  T9L_ULL, BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
-  { "u",   0, STD_C89, { T89_UI,  BADLEN,  BADLEN,  T89_UL,  T9L_ULL, BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
-  { "c",   0, STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
-  { "s",   1, STD_C89, { T89_C,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "pq", "cR", NULL },
-  { "p",   1, STD_C89, { T89_V,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "c",  NULL },
+  { "di", NULL, NULL,  0, STD_C89, { T89_I,   BADLEN,  BADLEN,  T89_L,   T9L_LL,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
+  { "ox", NULL, NULL,  0, STD_C89, { T89_UI,  BADLEN,  BADLEN,  T89_UL,  T9L_ULL, BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
+  { "u", NULL, NULL,   0, STD_C89, { T89_UI,  BADLEN,  BADLEN,  T89_UL,  T9L_ULL, BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
+  { "c", NULL, NULL,   0, STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
+  { "s", NULL, NULL,   1, STD_C89, { T89_C,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "pq", "cR", NULL },
+  { "p", NULL, NULL,   1, STD_C89, { T89_V,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "c",  NULL },
 
   /* Custom conversion specifiers.  */
 
   /* These will require a "tree" at runtime.  */
-  { "ADEFKSTVX",0,STD_C89,{ T89_V,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q+#",   "",   NULL },
+  { "ADEFKSTVX", "EK", "EK", 0,STD_C89,{ T89_V,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q+#",   "",   NULL },
 
-  { "v", 0,STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q#",  "",   NULL },
+  { "v", NULL, NULL, 0,STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q#",  "",   NULL },
 
   /* These accept either an 'int' or an 'enum tree_code' (which is handled as an 'int'.)  */
-  { "CLOPQ",0,STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
+  { "CLOPQ", NULL, NULL, 0,STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q",  "",   NULL },
 
-  { "r",   1, STD_C89, { T89_C,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "",    "cR",   NULL },
-  { "<>'R",0, STD_C89, NOARGUMENTS, "",      "",   NULL },
-  { "m",   0, STD_C89, NOARGUMENTS, "q",     "",   NULL },
-  { "Z",   1, STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "",    "", &gcc_tdiag_char_table[0] },
-  { NULL,  0, STD_C89, NOLENGTHS, NULL, NULL, NULL }
+  { "r", NULL, NULL,   1, STD_C89, { T89_C,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "",    "cR",   NULL },
+  { "<>'R", "<'R", ">'R", 0, STD_C89, NOARGUMENTS, "",      "",   NULL },
+  { "m", NULL, NULL,   0, STD_C89, NOARGUMENTS, "q",     "",   NULL },
+  { "Z", NULL, NULL,   1, STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "",    "", &gcc_tdiag_char_table[0] },
+  { NULL, NULL, NULL, 0, STD_C89, NOLENGTHS, NULL, NULL, NULL }
 };
 
 static const format_char_info gcc_gfc_char_table[] =
 {
   /* C89 conversion specifiers.  */
-  { "di",  0, STD_C89, { T89_I,   BADLEN,  BADLEN,  T89_L,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q", "", NULL },
-  { "u",   0, STD_C89, { T89_UI,  BADLEN,  BADLEN,  T89_UL,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q", "", NULL },
-  { "c",   0, STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q", "", NULL },
-  { "s",   1, STD_C89, { T89_C,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q", "cR", NULL },
+  { "di", NULL, NULL,  0, STD_C89, { T89_I,   BADLEN,  BADLEN,  T89_L,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q", "", NULL },
+  { "u", NULL, NULL,   0, STD_C89, { T89_UI,  BADLEN,  BADLEN,  T89_UL,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q", "", NULL },
+  { "c", NULL, NULL,   0, STD_C89, { T89_I,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q", "", NULL },
+  { "s", NULL, NULL,   1, STD_C89, { T89_C,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "q", "cR", NULL },
 
   /* gfc conversion specifiers.  */
 
-  { "C",   0, STD_C89, NOARGUMENTS, "",      "",   NULL },
+  { "C", NULL, NULL,   0, STD_C89, NOARGUMENTS, "",      "",   NULL },
 
   /* This will require a "locus" at runtime.  */
-  { "L",   0, STD_C89, { T89_V,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "", "R", NULL },
+  { "L", NULL, NULL,   0, STD_C89, { T89_V,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "", "R", NULL },
 
   /* These will require nothing.  */
-  { "<>",0, STD_C89, NOARGUMENTS, "",      "",   NULL },
-  { NULL,  0, STD_C89, NOLENGTHS, NULL, NULL, NULL }
+  { "<>", "<", ">", 0, STD_C89, NOARGUMENTS, "",      "",   NULL },
+  { NULL, NULL, NULL, 0, STD_C89, NOLENGTHS, NULL, NULL, NULL }
 };
 
 static const format_char_info scan_char_table[] =
 {
   /* C89 conversion specifiers.  */
-  { "di",    1, STD_C89, { T89_I,   T99_SC,  T89_S,   T89_L,   T9L_LL,  TEX_LL,  T99_SST, T99_PD,  T99_IM,  BADLEN,  BADLEN,  BADLEN }, "*w'I", "W",   NULL },
-  { "u",     1, STD_C89, { T89_UI,  T99_UC,  T89_US,  T89_UL,  T9L_ULL, TEX_ULL, T99_ST,  T99_UPD, T99_UIM, BADLEN,  BADLEN,  BADLEN }, "*w'I", "W",   NULL },
-  { "oxX",   1, STD_C89, { T89_UI,  T99_UC,  T89_US,  T89_UL,  T9L_ULL, TEX_ULL, T99_ST,  T99_UPD, T99_UIM, BADLEN,  BADLEN,  BADLEN }, "*w",   "W",   NULL },
-  { "efgEG", 1, STD_C89, { T89_F,   BADLEN,  BADLEN,  T89_D,   BADLEN,  T89_LD,  BADLEN,  BADLEN,  BADLEN,  TEX_D32, TEX_D64, TEX_D128 }, "*w'",  "W",   NULL },
-  { "c",     1, STD_C89, { T89_C,   BADLEN,  BADLEN,  T94_W,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "*mw",   "cW",  NULL },
-  { "s",     1, STD_C89, { T89_C,   BADLEN,  BADLEN,  T94_W,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "*amw",  "cW",  NULL },
-  { "[",     1, STD_C89, { T89_C,   BADLEN,  BADLEN,  T94_W,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "*amw",  "cW[", NULL },
-  { "p",     2, STD_C89, { T89_V,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "*w",   "W",   NULL },
-  { "n",     1, STD_C89, { T89_I,   T99_SC,  T89_S,   T89_L,   T9L_LL,  BADLEN,  T99_SST, T99_PD,  T99_IM,  BADLEN,  BADLEN,  BADLEN }, "",     "W",   NULL },
+  { "di", NULL, NULL,    1, STD_C89, { T89_I,   T99_SC,  T89_S,   T89_L,   T9L_LL,  TEX_LL,  T99_SST, T99_PD,  T99_IM,  BADLEN,  BADLEN,  BADLEN }, "*w'I", "W",   NULL },
+  { "u", NULL, NULL,     1, STD_C89, { T89_UI,  T99_UC,  T89_US,  T89_UL,  T9L_ULL, TEX_ULL, T99_ST,  T99_UPD, T99_UIM, BADLEN,  BADLEN,  BADLEN }, "*w'I", "W",   NULL },
+  { "oxX", NULL, NULL,   1, STD_C89, { T89_UI,  T99_UC,  T89_US,  T89_UL,  T9L_ULL, TEX_ULL, T99_ST,  T99_UPD, T99_UIM, BADLEN,  BADLEN,  BADLEN }, "*w",   "W",   NULL },
+  { "efgEG", NULL, NULL, 1, STD_C89, { T89_F,   BADLEN,  BADLEN,  T89_D,   BADLEN,  T89_LD,  BADLEN,  BADLEN,  BADLEN,  TEX_D32, TEX_D64, TEX_D128 }, "*w'",  "W",   NULL },
+  { "c", NULL, NULL,     1, STD_C89, { T89_C,   BADLEN,  BADLEN,  T94_W,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "*mw",   "cW",  NULL },
+  { "s", NULL, NULL,     1, STD_C89, { T89_C,   BADLEN,  BADLEN,  T94_W,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "*amw",  "cW",  NULL },
+  { "[", NULL, NULL,     1, STD_C89, { T89_C,   BADLEN,  BADLEN,  T94_W,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "*amw",  "cW[", NULL },
+  { "p", NULL, NULL,     2, STD_C89, { T89_V,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "*w",   "W",   NULL },
+  { "n", NULL, NULL,     1, STD_C89, { T89_I,   T99_SC,  T89_S,   T89_L,   T9L_LL,  BADLEN,  T99_SST, T99_PD,  T99_IM,  BADLEN,  BADLEN,  BADLEN }, "",     "W",   NULL },
   /* C99 conversion specifiers.  */
-  { "F",   1, STD_C99, { T99_F,   BADLEN,  BADLEN,  T99_D,   BADLEN,  T99_LD,  BADLEN,  BADLEN,  BADLEN,  TEX_D32, TEX_D64, TEX_D128 }, "*w'",  "W",   NULL },
-  { "aA",   1, STD_C99, { T99_F,   BADLEN,  BADLEN,  T99_D,   BADLEN,  T99_LD,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "*w'",  "W",   NULL },
+  { "F", NULL, NULL,   1, STD_C99, { T99_F,   BADLEN,  BADLEN,  T99_D,   BADLEN,  T99_LD,  BADLEN,  BADLEN,  BADLEN,  TEX_D32, TEX_D64, TEX_D128 }, "*w'",  "W",   NULL },
+  { "aA", NULL, NULL,   1, STD_C99, { T99_F,   BADLEN,  BADLEN,  T99_D,   BADLEN,  T99_LD,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "*w'",  "W",   NULL },
   /* X/Open conversion specifiers.  */
-  { "C",     1, STD_EXT, { TEX_W,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "*mw",   "W",   NULL },
-  { "S",     1, STD_EXT, { TEX_W,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "*amw",  "W",   NULL },
-  { NULL, 0, STD_C89, NOLENGTHS, NULL, NULL, NULL }
+  { "C", NULL, NULL,     1, STD_EXT, { TEX_W,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "*mw",   "W",   NULL },
+  { "S", NULL, NULL,     1, STD_EXT, { TEX_W,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN }, "*amw",  "W",   NULL },
+  { NULL, NULL, NULL, 0, STD_C89, NOLENGTHS, NULL, NULL, NULL }
 };
 
 static const format_char_info time_char_table[] =
 {
   /* C89 conversion specifiers.  */
-  { "ABZab",		0, STD_C89, NOLENGTHS, "^#",     "",   NULL },
-  { "cx",		0, STD_C89, NOLENGTHS, "E",      "3",  NULL },
-  { "HIMSUWdmw",	0, STD_C89, NOLENGTHS, "-_0Ow",  "",   NULL },
-  { "j",		0, STD_C89, NOLENGTHS, "-_0Ow",  "o",  NULL },
-  { "p",		0, STD_C89, NOLENGTHS, "#",      "",   NULL },
-  { "X",		0, STD_C89, NOLENGTHS, "E",      "",   NULL },
-  { "y",		0, STD_C89, NOLENGTHS, "EO-_0w", "4",  NULL },
-  { "Y",		0, STD_C89, NOLENGTHS, "-_0EOw", "o",  NULL },
-  { "%",		0, STD_C89, NOLENGTHS, "",       "",   NULL },
+  { "ABZab",	 NULL, NULL, 0, STD_C89, NOLENGTHS, "^#",     "",   NULL },
+  { "cx",	 NULL, NULL, 0, STD_C89, NOLENGTHS, "E",      "3",  NULL },
+  { "HIMSUWdmw", NULL, NULL, 0, STD_C89, NOLENGTHS, "-_0Ow",  "",   NULL },
+  { "j",	 NULL, NULL, 0, STD_C89, NOLENGTHS, "-_0Ow",  "o",  NULL },
+  { "p",	 NULL, NULL, 0, STD_C89, NOLENGTHS, "#",      "",   NULL },
+  { "X",	 NULL, NULL, 0, STD_C89, NOLENGTHS, "E",      "",   NULL },
+  { "y",	 NULL, NULL, 0, STD_C89, NOLENGTHS, "EO-_0w", "4",  NULL },
+  { "Y",	 NULL, NULL, 0, STD_C89, NOLENGTHS, "-_0EOw", "o",  NULL },
+  { "%",	 NULL, NULL, 0, STD_C89, NOLENGTHS, "",       "",   NULL },
   /* C99 conversion specifiers.  */
-  { "C",		0, STD_C99, NOLENGTHS, "-_0EOw", "o",  NULL },
-  { "D",		0, STD_C99, NOLENGTHS, "",       "2",  NULL },
-  { "eVu",		0, STD_C99, NOLENGTHS, "-_0Ow",  "",   NULL },
-  { "FRTnrt",		0, STD_C99, NOLENGTHS, "",       "",   NULL },
-  { "g",		0, STD_C99, NOLENGTHS, "O-_0w",  "2o", NULL },
-  { "G",		0, STD_C99, NOLENGTHS, "-_0Ow",  "o",  NULL },
-  { "h",		0, STD_C99, NOLENGTHS, "^#",     "",   NULL },
-  { "z",		0, STD_C99, NOLENGTHS, "O",      "o",  NULL },
+  { "C",	 NULL, NULL, 0, STD_C99, NOLENGTHS, "-_0EOw", "o",  NULL },
+  { "D",	 NULL, NULL, 0, STD_C99, NOLENGTHS, "",       "2",  NULL },
+  { "eVu",	 NULL, NULL, 0, STD_C99, NOLENGTHS, "-_0Ow",  "",   NULL },
+  { "FRTnrt",	 NULL, NULL, 0, STD_C99, NOLENGTHS, "",       "",   NULL },
+  { "g",	 NULL, NULL, 0, STD_C99, NOLENGTHS, "O-_0w",  "2o", NULL },
+  { "G",	 NULL, NULL, 0, STD_C99, NOLENGTHS, "-_0Ow",  "o",  NULL },
+  { "h",	 NULL, NULL, 0, STD_C99, NOLENGTHS, "^#",     "",   NULL },
+  { "z",	 NULL, NULL, 0, STD_C99, NOLENGTHS, "O",      "o",  NULL },
   /* GNU conversion specifiers.  */
-  { "kls",		0, STD_EXT, NOLENGTHS, "-_0Ow",  "",   NULL },
-  { "P",		0, STD_EXT, NOLENGTHS, "",       "",   NULL },
-  { NULL,		0, STD_C89, NOLENGTHS, NULL, NULL, NULL }
+  { "kls",	 NULL, NULL, 0, STD_EXT, NOLENGTHS, "-_0Ow",  "",   NULL },
+  { "P",	 NULL, NULL, 0, STD_EXT, NOLENGTHS, "",       "",   NULL },
+  { NULL,	 NULL, NULL, 0, STD_C89, NOLENGTHS, NULL, NULL, NULL }
 };
 
 static const format_char_info monetary_char_table[] =
 {
-  { "in", 0, STD_C89, { T89_D, BADLEN, BADLEN, BADLEN, BADLEN, T89_LD, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "=^+(!-w#p", "", NULL },
-  { NULL, 0, STD_C89, NOLENGTHS, NULL, NULL, NULL }
+  { "in", NULL, NULL, 0, STD_C89, { T89_D, BADLEN, BADLEN, BADLEN, BADLEN, T89_LD, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN, BADLEN }, "=^+(!-w#p", "", NULL },
+  { NULL, NULL, NULL, 0, STD_C89, NOLENGTHS, NULL, NULL, NULL }
 };
 
 /* This must be in the same order as enum format_type.  */
@@ -1689,7 +1689,8 @@  class flag_chars_t
 		 tree format_string_cst,
 		 location_t format_string_loc,
 		 const char * const orig_format_chars,
-		 char format_char);
+		 char format_char,
+		 bool quoted);
   int get_alloc_flag (const format_kind_info *fki);
   int assignment_suppression_p (const format_kind_info *fki);
 
@@ -1839,7 +1840,9 @@  flag_chars_t::add_char (char ch)
   m_flag_chars[i] = 0;
 }
 
-/* Validate the individual flags used, removing any that are invalid.  */
+/* Validate the individual flags used, removing any that are invalid.
+   On entry, QUOTED is set to true if the flags being validated appear
+   within a quoted sequence (as in between GCC's %< and %> directives).  */
 
 void
 flag_chars_t::validate (const format_kind_info *fki,
@@ -1849,10 +1852,13 @@  flag_chars_t::validate (const format_kind_info *fki,
 			tree format_string_cst,
 			location_t format_string_loc,
 			const char * const orig_format_chars,
-			char format_char)
+			char format_char,
+			bool quoted)
 {
   int i;
   int d = 0;
+  bool quotflag = false;
+
   for (i = 0; m_flag_chars[i] != 0; i++)
     {
       const format_flag_spec *s = get_flag_spec (flag_specs,
@@ -1860,6 +1866,10 @@  flag_chars_t::validate (const format_kind_info *fki,
       m_flag_chars[i - d] = m_flag_chars[i];
       if (m_flag_chars[i] == fki->length_code_char)
 	continue;
+
+      /* Remember if a quoting flag is seen.  */
+      quotflag |= s->quoting;
+
       if (strchr (fci->flag_chars, m_flag_chars[i]) == 0)
 	{
 	  format_warning_at_char (format_string_loc, format_string_cst,
@@ -1891,8 +1901,32 @@  flag_chars_t::validate (const format_kind_info *fki,
 			    format_char, fki->name);
 	    }
 	}
+      /* Detect quoting directives used within a quoted sequence, such
+	 as GCC's "%<...%qE".  */
+      if (quoted && s->quoting)
+	{
+	  format_warning_at_char (format_string_loc, format_string_cst,
+				  format_chars - orig_format_chars,
+				  OPT_Wformat_,
+				  "%s used within a quoted sequence",
+				  _(s->name));
+	}
     }
   m_flag_chars[i - d] = 0;
+
+  if (!quoted
+      && !quotflag
+      && fci->quote_begin_chars
+      && !strchr (fci->quote_begin_chars, format_char)
+      && fci->quote_end_chars
+      && !strchr (fci->quote_end_chars, format_char))
+    {
+      format_warning_at_char (format_string_loc, format_string_cst,
+			      format_chars - orig_format_chars,
+			      OPT_Wformat_,
+			      "%qc conversion used unquoted",
+			      format_char);
+    }
 }
 
 /* Determine if an assignment-allocation has been set, requiring
@@ -2704,6 +2738,9 @@  check_format_info_main (format_check_results *res,
      and it didn't use $; 1 if $ formats are in use.  */
   int has_operand_number = -1;
 
+  /* Vector of pointers to opening quoting directives (like GCC %<).  */
+  auto_vec<const char*> quotdirs;
+
   init_dollar_format_checking (info->first_arg_num, first_fillin_param);
 
   while (*format_chars != 0)
@@ -2785,11 +2822,42 @@  check_format_info_main (format_check_results *res,
 
       flag_chars.validate (fki, fci, flag_specs, format_chars,
 			   format_string_cst,
-			   format_string_loc, orig_format_chars, format_char);
+			   format_string_loc, orig_format_chars, format_char,
+			   quotdirs.length () > 0);
 
       const int alloc_flag = flag_chars.get_alloc_flag (fki);
       const bool suppressed = flag_chars.assignment_suppression_p (fki);
 
+      /* Diagnose nested or unmatched quoting directives such as GCC's
+	 "%<...%<" and "%>...%>".  As a special case, a directive can
+	 be considered to both begin and end quoting (e.g., GCC's %E).
+	 Such a directive is recognized but not diagosed.  */
+      bool begin_quote = (fci->quote_begin_chars
+			  && strchr (fci->quote_begin_chars, format_char));
+      bool end_quote = (fci->quote_end_chars
+			&& strchr (fci->quote_end_chars, format_char));
+
+      if (begin_quote && !end_quote)
+	{
+	  if (quotdirs.length ())
+	    format_warning_at_char (format_string_loc, format_string_cst,
+				    format_chars - orig_format_chars,
+				    OPT_Wformat_,
+				    "nested quoting directive");
+	  quotdirs.safe_push (format_chars);
+	}
+      else if (!begin_quote && end_quote)
+	{
+	  if (quotdirs.length ())
+	    quotdirs.pop ();
+	  else
+	    format_warning_at_char (format_string_loc, format_string_cst,
+				    format_chars - orig_format_chars,
+				    OPT_Wformat_,
+				    "unmatched quoting directive");
+	}
+
+
       /* Validate the pairs of flags used.  */
       arg_parser.validate_flag_pairs (fci, format_char);
 
@@ -2834,6 +2902,11 @@  check_format_info_main (format_check_results *res,
     }
   if (has_operand_number > 0)
     finish_dollar_format_checking (res, fki->flags & (int) FMT_FLAG_DOLLAR_GAP_POINTER_OK);
+
+  if (quotdirs.length ())
+    format_warning_at_char (format_string_loc, format_string_cst,
+			    quotdirs.pop () - orig_format_chars,
+			    OPT_Wformat_, "unterminated quoting directive");
 }
 
 /* Check the argument types from a single format conversion (possibly
diff --git a/gcc/c-family/c-format.h b/gcc/c-family/c-format.h
index 13ca8ea..8932861 100644
--- a/gcc/c-family/c-format.h
+++ b/gcc/c-family/c-format.h
@@ -132,6 +132,11 @@  struct format_type_detail
 struct format_char_info
 {
   const char *format_chars;
+  /* Strings of FORMAT_CHARS characters that begin and end quoting,
+     respectively, and pairs of which should be matched in the same
+     format string.  NULL when no such pairs exist.  */
+  const char *quote_begin_chars;
+  const char *quote_end_chars;
   int pointer_count;
   enum format_std_version std;
   /* Types accepted for each length modifier.  */
@@ -178,6 +183,8 @@  struct format_flag_spec
   /* Nonzero if the next character after this flag in the format should
      be skipped ('=' in strfmon), zero otherwise.  */
   int skip_next_char;
+  /* True if the flag introduces quoting (as in GCC's %qE).  */
+  bool quoting;
   /* The name to use for this flag in diagnostic messages.  For example,
      N_("'0' flag"), N_("field width").  */
   const char *name;
diff --git a/gcc/testsuite/gcc.dg/format/ext-9.c b/gcc/testsuite/gcc.dg/format/ext-9.c
new file mode 100644
index 0000000..cc64820
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/format/ext-9.c
@@ -0,0 +1,21 @@ 
+/* Test for GCC internal format directives.
+   { dg-do compile }
+   { dg-options "-std=gnu99 -Wformat" } */
+
+
+void diag (const char*, ...) __attribute__ ((format (__gcc_tdiag__, 1, 2)));
+
+void test (void)
+{
+  diag ("%<");   /* { dg-warning "unterminated quoting directive" } */
+  diag ("%>");   /* { dg-warning "unmatched quoting directive " } */
+  diag ("%<foo%<bar%>%>");   /* { dg-warning "nested quoting directive" } */
+
+  diag ("%<%qD%>");   /* { dg-warning ".q. flag used within a quoted sequence" } */
+  diag ("%<%qE%>");   /* { dg-warning ".q. flag used within a quoted sequence" } */
+  diag ("%<%qT%>");   /* { dg-warning ".q. flag used within a quoted sequence" } */
+
+  diag ("%D");   /* { dg-warning ".D. conversion used unquoted" } */
+  diag ("%E");
+  diag ("%T");   /* { dg-warning ".T. conversion used unquoted" } */
+}