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[c++/68475] ICE with fno-exceptions

Message ID 56FBC1E3.50607@acm.org
State New
Headers show

Commit Message

Nathan Sidwell March 30, 2016, 12:09 p.m. UTC 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68475

This patch fixes an ICE with -fno-exceptions.  We were not checking eh spec 
equality when merging decls, leading to a checking-assert blowing up later.  As 
postulated in the bug report, always checking leads to good behaviour.  Even 
though we ignore the eh spec when generating code, we should check the source is 
well formed.

tested on x86_64-linux, ok?

nathan

Comments

Jason Merrill March 30, 2016, 1:44 p.m. UTC | #1 
On 03/30/2016 08:09 AM, Nathan Sidwell wrote:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68475
>
> This patch fixes an ICE with -fno-exceptions.  We were not checking eh
> spec equality when merging decls, leading to a checking-assert blowing
> up later.  As postulated in the bug report, always checking leads to
> good behaviour.  Even though we ignore the eh spec when generating code,
> we should check the source is well formed.

Hmm, I think the use of the flag there was meant to allow leaving the 
exception specification off in some declarations.  I'm open to getting 
stricter, but I'd prefer to make it a pedwarn when !flag_exceptions 
rather than an error, in which case we still need to deal with the 
mismatch in merge_exception_specifiers.

Jason
diff mbox

Patch

2016-03-30  Nathan Sidwell  <nathan@acm.org>

	PR c++/68475
	* decl.c (check_redeclaration_exception_specification): Check
	regardless of -fno-exceptions.

	PR c++/68475
	* g++.dg/eh/spec12.C: New.

Index: cp/decl.c
===================================================================
--- cp/decl.c	(revision 234516)
+++ cp/decl.c	(working copy)
@@ -1200,9 +1200,11 @@  check_redeclaration_exception_specificat
      If any declaration of a function has an exception-specification,
      all declarations, including the definition and an explicit
      specialization, of that function shall have an
-     exception-specification with the same set of type-ids.  */
+     exception-specification with the same set of type-ids.
+
+     Even when fno-exceptions is in effect, any specifications must
+     still  match.   */
   if (! DECL_IS_BUILTIN (old_decl)
-      && flag_exceptions
       && !comp_except_specs (new_exceptions, old_exceptions, ce_normal))
     {
       const char *msg
Index: testsuite/g++.dg/eh/spec12.C
===================================================================
--- testsuite/g++.dg/eh/spec12.C	(nonexistent)
+++ testsuite/g++.dg/eh/spec12.C	(working copy)
@@ -0,0 +1,19 @@ 
+// { dg-do compile }
+// { dg-additional-options "-fno-exceptions" }
+
+// PR68475 we used to not check eh spec matching with -fno-exceptions,
+// but this could lead to ICEs.
+
+template < typename > struct traits;
+
+template < typename T > struct X
+{
+  X & operator = (X &&) noexcept (traits < T >::foo ()); // { dg-inform "previous declaration" }
+};
+
+template < typename T >
+X < T > &
+X < T >::operator = (X &&) noexcept (traits < T >::bar ()) // { dg-error "different exception specifier" }
+{
+  return *this;
+}