Re: [PATCH] c++: Fix ICE-on-invalid with -Wvexing-parse [PR97881]

[Marek Polacek via Gcc-patches]

On Fri, Nov 20, 2020 at 05:23:56PM -0500, Jason Merrill wrote:
> On 11/17/20 2:32 PM, Marek Polacek wrote:
> > --- /dev/null
> > +++ b/gcc/testsuite/g++.dg/warn/Wvexing-parse9.C
> > @@ -0,0 +1,8 @@
> > +// PR c++/97881
> > +// { dg-do compile }
> > +
> > +void
> > +cb ()
> > +{
> > +  volatile _Atomic (int) a1; // { dg-error "expected initializer" }
> 
> I'm not sure it's useful to test for this particular error, since a missing
> initializer isn't the problem with this declaration.  OK either way.

True, I pushed the patch with { dg-error "" } instead.


Thanks,
Marek

Re: [PATCH] c++: Fix ICE-on-invalid with -Wvexing-parse [PR97881]

[Jason Merrill via Gcc-patches]

On 11/17/20 2:32 PM, Marek Polacek wrote:

This invalid (?) code broke my assumption that if decl_specifiers->type
is null, there must be any type-specifiers.  Turn the assert into an if
to fix this crash.

Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?

gcc/cp/ChangeLog:

PR c++/97881
* parser.c (warn_about_ambiguous_parse): Only assume "int" if we
actually saw any type-specifiers.

gcc/testsuite/ChangeLog:

PR c++/97881
* g++.dg/warn/Wvexing-parse9.C: New test.
---
  gcc/cp/parser.c| 11 +--
  gcc/testsuite/g++.dg/warn/Wvexing-parse9.C |  8 
  2 files changed, 13 insertions(+), 6 deletions(-)
  create mode 100644 gcc/testsuite/g++.dg/warn/Wvexing-parse9.C

diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index b7ef259b048..7a6bf4ad2cf 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -20792,13 +20792,12 @@ warn_about_ambiguous_parse (const 
cp_decl_specifier_seq *decl_specifiers,
if (same_type_p (type, void_type_node))
return;
  }
+  else if (decl_specifiers->any_type_specifiers_p)
+/* Code like long f(); will have null ->type.  If we have any
+   type-specifiers, pretend we've seen int.  */
+type = integer_type_node;
else
-{
-  /* Code like long f(); will have null ->type.  If we have any
-type-specifiers, pretend we've seen int.  */
-  gcc_checking_assert (decl_specifiers->any_type_specifiers_p);
-  type = integer_type_node;
-}
+return;
  
auto_diagnostic_group d;

location_t loc = declarator->u.function.parens_loc;
diff --git a/gcc/testsuite/g++.dg/warn/Wvexing-parse9.C 
b/gcc/testsuite/g++.dg/warn/Wvexing-parse9.C
new file mode 100644
index 000..dc4198d6c5e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wvexing-parse9.C
@@ -0,0 +1,8 @@
+// PR c++/97881
+// { dg-do compile }
+
+void
+cb ()
+{
+  volatile _Atomic (int) a1; // { dg-error "expected initializer" }


I'm not sure it's useful to test for this particular error, since a 
missing initializer isn't the problem with this declaration.  OK either way.



+}

base-commit: a5f9c27bfc4417224e332392bb81a2d733b2b5bf