--- gcc/configure.ac.jj	2020-04-29 10:21:25.061999873 +0200
+++ gcc/configure.ac	2020-04-29 13:26:51.515516959 +0200
@@ -986,6 +986,20 @@ AC_ARG_WITH(documentation-root-url,
 )
 AC_SUBST(DOCUMENTATION_ROOT_URL)
 
+# Allow overriding the default URL for GCC changes
+AC_ARG_WITH(changes-root-url,
+    AS_HELP_STRING([--with-changes-root-url=URL],
+                   [Root for GCC changes URLs]),
+    [case "$withval" in
+      yes) AC_MSG_ERROR([changes root URL not specified]) ;;
+      no)  AC_MSG_ERROR([changes root URL not specified]) ;;
+      *)   CHANGES_ROOT_URL="$withval"
+	   ;;
+     esac],
+     CHANGES_ROOT_URL="https://gcc.gnu.org/"
+)
+AC_SUBST(CHANGES_ROOT_URL)
+
 # Sanity check enable_languages in case someone does not run the toplevel
 # configure # script.
 AC_ARG_ENABLE(languages,
--- gcc/Makefile.in.jj	2020-02-27 09:28:46.129960135 +0100
+++ gcc/Makefile.in	2020-04-29 13:38:42.455008718 +0200
@@ -2187,6 +2187,7 @@ lto-wrapper$(exeext): $(LTO_WRAPPER_OBJS
 	mv -f T$@ $@
 
 CFLAGS-opts.o += -DDOCUMENTATION_ROOT_URL=\"@DOCUMENTATION_ROOT_URL@\"
+CFLAGS-opts.o += -DCHANGES_ROOT_URL=\"@CHANGES_ROOT_URL@\"
 
 # Files used by all variants of C or by the stand-alone pre-processor.
 
--- gcc/pretty-print.c.jj	2020-04-25 00:08:33.359759328 +0200
+++ gcc/pretty-print.c	2020-04-29 14:30:46.791792554 +0200
@@ -1020,6 +1020,8 @@ pp_indent (pretty_printer *pp)
     pp_space (pp);
 }
 
+static const char *end_url_string (pretty_printer *);
+
 /* The following format specifiers are recognized as being client independent:
    %d, %i: (signed) integer in base ten.
    %u: unsigned integer in base ten.
@@ -1038,6 +1040,8 @@ pp_indent (pretty_printer *pp)
    %%: '%'.
    %<: opening quote.
    %>: closing quote.
+   %{: URL start.
+   %}: URL end.
    %': apostrophe (should only be used in untranslated messages;
        translations should use appropriate punctuation directly).
    %@: diagnostic_event_id_ptr, for which event_id->known_p () must be true.
@@ -1051,7 +1055,7 @@ pp_indent (pretty_printer *pp)
    Arguments can be used sequentially, or through %N$ resp. *N$
    notation Nth argument after the format string.  If %N$ / *N$
    notation is used, it must be used for all arguments, except %m, %%,
-   %<, %> and %', which may not have a number, as they do not consume
+   %<, %>, %} and %', which may not have a number, as they do not consume
    an argument.  When %M$.*N$s is used, M must be N + 1.  (This may
    also be written %M$.*s, provided N is not otherwise used.)  The
    format string must have conversion specifiers with argument numbers
@@ -1084,7 +1088,7 @@ pp_format (pretty_printer *pp, text_info
   /* Formatting phase 1: split up TEXT->format_spec into chunks in
      pp_buffer (PP)->args[].  Even-numbered chunks are to be output
      verbatim, odd-numbered chunks are format specifiers.
-     %m, %%, %<, %>, and %' are replaced with the appropriate text at
+     %m, %%, %<, %>, %} and %' are replaced with the appropriate text at
      this point.  */
 
   memset (formatters, 0, sizeof formatters);
@@ -1133,6 +1137,15 @@ pp_format (pretty_printer *pp, text_info
 	  p++;
 	  continue;
 
+	case '}':
+	  {
+	    const char *endurlstr = end_url_string (pp);
+	    obstack_grow (&buffer->chunk_obstack, endurlstr,
+			  strlen (endurlstr));
+	  }
+	  p++;
+	  continue;
+
 	case 'R':
 	  {
 	    const char *colorstr = colorize_stop (pp_show_color (pp));
@@ -1445,6 +1458,10 @@ pp_format (pretty_printer *pp, text_info
 	  }
 	  break;
 
+	case '{':
+	  pp_begin_url (pp, va_arg (*text->args_ptr, const char *));
+	  break;
+
 	default:
 	  {
 	    bool ok;
@@ -2172,18 +2189,41 @@ void
 pp_begin_url (pretty_printer *pp, const char *url)
 {
   switch (pp->url_format)
-  {
-  case URL_FORMAT_NONE:
-    break;
-  case URL_FORMAT_ST:
-    pp_printf (pp, "\33]8;;%s\33\\", url);
-    break;
-  case URL_FORMAT_BEL:
-    pp_printf (pp, "\33]8;;%s\a", url);
-    break;
-  default:
-    gcc_unreachable ();
-  }
+    {
+    case URL_FORMAT_NONE:
+      break;
+    case URL_FORMAT_ST:
+      pp_string (pp, "\33]8;;");
+      pp_string (pp, url);
+      pp_string (pp, "\33\\");
+      break;
+    case URL_FORMAT_BEL:
+      pp_string (pp, "\33]8;;");
+      pp_string (pp, url);
+      pp_string (pp, "\a");
+      break;
+    default:
+      gcc_unreachable ();
+    }
+}
+
+/* Helper function for pp_end_url and pp_format, return the "close URL" escape
+   sequence string.  */
+
+static const char *
+end_url_string (pretty_printer *pp)
+{
+  switch (pp->url_format)
+    {
+    case URL_FORMAT_NONE:
+      return "";
+    case URL_FORMAT_ST:
+      return "\33]8;;\33\\";
+    case URL_FORMAT_BEL:
+      return "\33]8;;\a";
+    default:
+      gcc_unreachable ();
+    }
 }
 
 /* If URL-printing is enabled, write a "close URL" escape sequence to PP.  */
@@ -2191,19 +2231,8 @@ pp_begin_url (pretty_printer *pp, const
 void
 pp_end_url (pretty_printer *pp)
 {
-  switch (pp->url_format)
-  {
-  case URL_FORMAT_NONE:
-    break;
-  case URL_FORMAT_ST:
-    pp_string (pp, "\33]8;;\33\\");
-    break;
-  case URL_FORMAT_BEL:
-    pp_string (pp, "\33]8;;\a");
-    break;
-  default:
-    gcc_unreachable ();
-  }
+  if (pp->url_format != URL_FORMAT_NONE)
+    pp_string (pp, end_url_string (pp));
 }
 
 #if CHECKING_P
--- gcc/opts.h.jj	2020-02-24 09:02:27.332710905 +0100
+++ gcc/opts.h	2020-04-29 13:56:55.621826605 +0200
@@ -464,6 +464,7 @@ extern void parse_options_from_collect_g
 						    int *);
 
 extern void prepend_xassembler_to_collect_as_options (const char *, obstack *);
+extern char *get_changes_url (const char *);
 
 /* Set OPTION in OPTS to VALUE if the option is not set in OPTS_SET.  */
 
--- gcc/opts.c.jj	2020-04-27 23:28:18.865609469 +0200
+++ gcc/opts.c	2020-04-29 13:42:13.033891253 +0200
@@ -3190,6 +3190,15 @@ get_option_url (diagnostic_context *, in
     return NULL;
 }
 
+/* Given "gcc-10/changes.html#foobar", return that URL under
+   CHANGES_ROOT_URL (see --with-changes-root-url).  */
+
+char *
+get_changes_url (const char *str)
+{
+  return concat (CHANGES_ROOT_URL, str, NULL);
+}
+
 #if CHECKING_P
 
 namespace selftest {
--- gcc/config/arm/arm.c.jj	2020-04-29 13:12:46.736007298 +0200
+++ gcc/config/arm/arm.c	2020-04-29 14:34:04.878864236 +0200
@@ -6416,6 +6416,8 @@ aapcs_vfp_is_call_or_return_candidate (e
 	      && ((alt = aapcs_vfp_sub_candidate (type, &new_mode, NULL))
 		  != ag_count))
 	    {
+	      const char *url
+		= get_changes_url ("gcc-10/changes.html#empty_base");
 	      gcc_assert (alt == -1);
 	      last_reported_type_uid = uid;
 	      /* Use TYPE_MAIN_VARIANT to strip any redundant const
@@ -6423,11 +6425,14 @@ aapcs_vfp_is_call_or_return_candidate (e
 	      if (warn_psabi_flags & WARN_PSABI_NO_UNIQUE_ADDRESS)
 		inform (input_location, "parameter passing for argument of "
 			"type %qT with %<[[no_unique_address]]%> members "
-			"changed in GCC 10.1", TYPE_MAIN_VARIANT (type));
+			"changed in %{GCC 10.1%}",
+			TYPE_MAIN_VARIANT (type), url);
 	      else if (warn_psabi_flags & WARN_PSABI_EMPTY_CXX17_BASE)
 		inform (input_location, "parameter passing for argument of "
 			"type %qT when C++17 is enabled changed to match "
-			"C++14 in GCC 10.1", TYPE_MAIN_VARIANT (type));
+			"C++14 in %{GCC 10.1%}",
+			TYPE_MAIN_VARIANT (type), url);
+	      free (url);
 	    }
 	  *count = ag_count;
 	}
--- gcc/config/aarch64/aarch64.c.jj	2020-04-29 13:12:46.715007609 +0200
+++ gcc/config/aarch64/aarch64.c	2020-04-29 14:35:06.712950146 +0200
@@ -16883,6 +16883,8 @@ aarch64_vfp_is_call_or_return_candidate
 	      && ((alt = aapcs_vfp_sub_candidate (type, &new_mode, NULL))
 		  != ag_count))
 	    {
+	      const char *url
+		= get_changes_url ("gcc-10/changes.html#empty_base");
 	      gcc_assert (alt == -1);
 	      last_reported_type_uid = uid;
 	      /* Use TYPE_MAIN_VARIANT to strip any redundant const
@@ -16890,11 +16892,14 @@ aarch64_vfp_is_call_or_return_candidate
 	      if (warn_psabi_flags & WARN_PSABI_NO_UNIQUE_ADDRESS)
 		inform (input_location, "parameter passing for argument of "
 			"type %qT with %<[[no_unique_address]]%> members "
-			"changed in GCC 10.1", TYPE_MAIN_VARIANT (type));
+			"changed in %{GCC 10.1%}",
+			TYPE_MAIN_VARIANT (type), url);
 	      else if (warn_psabi_flags & WARN_PSABI_EMPTY_CXX17_BASE)
 		inform (input_location, "parameter passing for argument of "
 			"type %qT when C++17 is enabled changed to match "
-			"C++14 in GCC 10.1", TYPE_MAIN_VARIANT (type));
+			"C++14 in %{GCC 10.1%}",
+			TYPE_MAIN_VARIANT (type), url);
+	      free (url);
 	    }
 
 	  if (is_ha != NULL) *is_ha = true;
--- gcc/config/rs6000/rs6000-call.c.jj	2020-04-29 09:00:46.642524337 +0200
+++ gcc/config/rs6000/rs6000-call.c	2020-04-29 13:50:45.873299042 +0200
@@ -68,6 +68,7 @@
 #include "tree-vrp.h"
 #include "tree-ssanames.h"
 #include "targhooks.h"
+#include "opts.h"
 
 #include "rs6000-internal.h"
 
@@ -5747,16 +5748,18 @@ rs6000_discover_homogeneous_aggregate (m
 		  unsigned uid = TYPE_UID (TYPE_MAIN_VARIANT (type));
 		  if (uid != last_reported_type_uid)
 		    {
+		      const char *url
+			= get_changes_url ("gcc-10/changes.html#empty_base");
 		      if (empty_base_seen & 1)
 			inform (input_location,
 				"parameter passing for argument of type %qT "
 				"when C++17 is enabled changed to match C++14 "
-				"in GCC 10.1", type);
+				"in %{GCC 10.1%}", type, url);
 		      else
 			inform (input_location,
 				"parameter passing for argument of type %qT "
 				"with %<[[no_unique_address]]%> members "
-				"changed in GCC 10.1", type);
+				"changed in %{GCC 10.1%}", type, url);
 		      last_reported_type_uid = uid;
 		    }
 		}
--- gcc/c-family/c-format.c.jj	2020-02-10 15:49:50.821300965 +0100
+++ gcc/c-family/c-format.c	2020-04-29 13:56:26.926250904 +0200
@@ -757,6 +757,8 @@ static const format_char_info asm_fprint
   { "<",   0, STD_C89, NOARGUMENTS, "",      "<",   NULL }, \
   { ">",   0, STD_C89, NOARGUMENTS, "",      ">",   NULL }, \
   { "'" ,  0, STD_C89, NOARGUMENTS, "",      "",    NULL }, \
+  { "{",   1, STD_C89, { T89_C,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "",   "cR", NULL }, \
+  { "}",   0, STD_C89, NOARGUMENTS, "",      "",    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_diag_char_table[0] }
--- gcc/configure.jj	2020-04-29 10:21:25.060999888 +0200
+++ gcc/configure	2020-04-29 13:28:07.423395043 +0200
@@ -819,6 +819,7 @@ accel_dir_suffix
 real_target_noncanonical
 enable_as_accelerator
 gnat_install_lib
+CHANGES_ROOT_URL
 DOCUMENTATION_ROOT_URL
 REPORT_BUGS_TEXI
 REPORT_BUGS_TO
@@ -967,6 +968,7 @@ with_specs
 with_pkgversion
 with_bugurl
 with_documentation_root_url
+with_changes_root_url
 enable_languages
 with_multilib_list
 with_zstd
@@ -1803,6 +1805,8 @@ Optional Packages:
   --with-bugurl=URL       Direct users to URL to report a bug
   --with-documentation-root-url=URL
                           Root for documentation URLs
+  --with-changes-root-url=URL
+                          Root for GCC changes URLs
   --with-multilib-list    select multilibs (AArch64, SH and x86-64 only)
   --with-zstd=PATH        specify prefix directory for installed zstd library.
                           Equivalent to --with-zstd-include=PATH/include plus
@@ -7857,6 +7861,23 @@ fi
 
 
 
+# Allow overriding the default URL for GCC changes
+
+# Check whether --with-changes-root-url was given.
+if test "${with_changes_root_url+set}" = set; then :
+  withval=$with_changes_root_url; case "$withval" in
+      yes) as_fn_error $? "changes root URL not specified" "$LINENO" 5 ;;
+      no)  as_fn_error $? "changes root URL not specified" "$LINENO" 5 ;;
+      *)   CHANGES_ROOT_URL="$withval"
+	   ;;
+     esac
+else
+  CHANGES_ROOT_URL="https://gcc.gnu.org/"
+
+fi
+
+
+
 # Sanity check enable_languages in case someone does not run the toplevel
 # configure # script.
 # Check whether --enable-languages was given.
@@ -18988,7 +19009,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 18991 "configure"
+#line 19012 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -19094,7 +19115,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 19097 "configure"
+#line 19118 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
