| Message ID | 20210422153433.3038330-1-ppalka@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | c++: Hard error with tentative parse and CTAD [PR87709] | expand |
On 4/22/21 11:34 AM, Patrick Palka wrote: > As described in detail in comment #4 of this PR, when tentatively > parsing a construct that can either be a type or an expression, if > during the type parse we encounter an unexpected template placeholder, > we need to simulate an error rather than issue a real error because the > subsequent expression parse can still succeed. > > Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for > trunk? OK. > gcc/cp/ChangeLog: > > PR c++/87709 > * parser.c (cp_parser_type_id_1): If we see a template > placeholder, first try simulating an error before issuing a real > error. > > gcc/testsuite/ChangeLog: > > PR c++/87709 > * g++.dg/cpp1z/class-deduction86.C: New test. > --- > gcc/cp/parser.c | 11 +++++++---- > gcc/testsuite/g++.dg/cpp1z/class-deduction86.C | 16 ++++++++++++++++ > 2 files changed, 23 insertions(+), 4 deletions(-) > create mode 100644 gcc/testsuite/g++.dg/cpp1z/class-deduction86.C > > diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c > index fba516efa23..e1b1617da68 100644 > --- a/gcc/cp/parser.c > +++ b/gcc/cp/parser.c > @@ -23270,10 +23270,13 @@ cp_parser_type_id_1 (cp_parser *parser, cp_parser_flags flags, > location_t loc = type_specifier_seq.locations[ds_type_spec]; > if (tree tmpl = CLASS_PLACEHOLDER_TEMPLATE (auto_node)) > { > - error_at (loc, "missing template arguments after %qT", > - auto_node); > - inform (DECL_SOURCE_LOCATION (tmpl), "%qD declared here", > - tmpl); > + if (!cp_parser_simulate_error (parser)) > + { > + error_at (loc, "missing template arguments after %qT", > + auto_node); > + inform (DECL_SOURCE_LOCATION (tmpl), "%qD declared here", > + tmpl); > + } > } > else if (parser->in_template_argument_list_p) > error_at (loc, "%qT not permitted in template argument", > diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction86.C b/gcc/testsuite/g++.dg/cpp1z/class-deduction86.C > new file mode 100644 > index 00000000000..a198ed24ec6 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction86.C > @@ -0,0 +1,16 @@ > +// PR c++/87709 > +// { dg-do compile { target c++17 } } > + > +template <class T> > +struct lit { > + lit(T) { } > +}; > + > +template <class T> > +int operator+(lit<T>, lit<T>) { > + return 0; > +} > + > +auto r2 = (lit(0)) + lit(0); > + > +static_assert(sizeof(lit(0))); >
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c index fba516efa23..e1b1617da68 100644 --- a/gcc/cp/parser.c +++ b/gcc/cp/parser.c @@ -23270,10 +23270,13 @@ cp_parser_type_id_1 (cp_parser *parser, cp_parser_flags flags, location_t loc = type_specifier_seq.locations[ds_type_spec]; if (tree tmpl = CLASS_PLACEHOLDER_TEMPLATE (auto_node)) { - error_at (loc, "missing template arguments after %qT", - auto_node); - inform (DECL_SOURCE_LOCATION (tmpl), "%qD declared here", - tmpl); + if (!cp_parser_simulate_error (parser)) + { + error_at (loc, "missing template arguments after %qT", + auto_node); + inform (DECL_SOURCE_LOCATION (tmpl), "%qD declared here", + tmpl); + } } else if (parser->in_template_argument_list_p) error_at (loc, "%qT not permitted in template argument", diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction86.C b/gcc/testsuite/g++.dg/cpp1z/class-deduction86.C new file mode 100644 index 00000000000..a198ed24ec6 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction86.C @@ -0,0 +1,16 @@ +// PR c++/87709 +// { dg-do compile { target c++17 } } + +template <class T> +struct lit { + lit(T) { } +}; + +template <class T> +int operator+(lit<T>, lit<T>) { + return 0; +} + +auto r2 = (lit(0)) + lit(0); + +static_assert(sizeof(lit(0)));