diff mbox

[C++] One more error + error to error + inform and a subtler issue

Message ID 57611CB1.1000103@oracle.com
State New
Headers show

Commit Message

Paolo Carlini June 15, 2016, 9:15 a.m. UTC 
Hi,

On 15/06/2016 03:30, Jason Merrill wrote:
> On Tue, Jun 14, 2016 at 6:12 PM, Paolo Carlini <paolo.carlini@oracle.com> wrote:
>> constexpr-specialization.C:7:26: error: redeclaration ‘constexpr int foo(T)
>> [with T = int]’ differs in ‘constexpr’
>>
>> constexpr-specialization.C:6:16: error: from previous declaration ‘constexpr
>> int foo(T) [with T = int]’
>>
>> see? The pretty printing of the previous declaration is very misleading
>> because it has constexpr in it!
> I'm guessing this happens because we're printing the type of the
> template plus template arguments, and the template is declared
> constexpr.  That should be easy enough to fix in dump_function_decl by
> looking at the instantiation when deciding whether to print
> "constexpr".
Indeed, it seems very easy to do and dump_function_decl should be fixed 
anyway, outside this specific error message. Also, we already had a 
similar issue for the exceptions. Thus the below, tested x86_64-linux.

Thanks,
Paolo.

//////////////////////
/cp
2016-06-15  Paolo Carlini  <paolo.carlini@oracle.com>

	* decl.c (validate_constexpr_redeclaration): Change pair of errors
	to error + inform.
	* error.c (dump_function_decl): Save the constexpr specifier too.

/testsuite
2016-06-15  Paolo Carlini  <paolo.carlini@oracle.com>

	* g++.dg/cpp0x/constexpr-specialization.C: Adjust for dg-message
	vs dg-error; test constexpr specifier too.

Comments

Jason Merrill June 17, 2016, 5:27 p.m. UTC | #1 
On Wed, Jun 15, 2016 at 5:15 AM, Paolo Carlini <paolo.carlini@oracle.com> wrote:
> +  /* Likewise for the constexpr specifier, in case t is a specialization
> +     and we are emitting an error about an incompatible redeclaration.  */

It doesn't need to be in an error about a redeclaration; in general a
specialization can differ in 'constexpr' from its template.  OK with
the second line removed from the comment.

Jason
diff mbox

Patch

Index: cp/decl.c
===================================================================
--- cp/decl.c	(revision 237472)
+++ cp/decl.c	(working copy)
@@ -1278,8 +1278,11 @@  validate_constexpr_redeclaration (tree old_decl, t
 	  && DECL_TEMPLATE_SPECIALIZATION (new_decl))
 	return true;
 
-      error ("redeclaration %q+D differs in %<constexpr%>", new_decl);
-      error ("from previous declaration %q+D", old_decl);
+      error_at (DECL_SOURCE_LOCATION (new_decl),
+		"redeclaration %qD differs in %<constexpr%> "
+		"from previous declaration", new_decl);
+      inform (DECL_SOURCE_LOCATION (old_decl),
+	      "previous declaration %qD", old_decl);
       return false;
     }
   return true;
Index: cp/error.c
===================================================================
--- cp/error.c	(revision 237472)
+++ cp/error.c	(working copy)
@@ -1486,6 +1486,7 @@  dump_function_decl (cxx_pretty_printer *pp, tree t
   int show_return = flags & TFF_RETURN_TYPE || flags & TFF_DECL_SPECIFIERS;
   int do_outer_scope = ! (flags & TFF_UNQUALIFIED_NAME);
   tree exceptions;
+  bool constexpr_p;
 
   flags &= ~(TFF_UNQUALIFIED_NAME | TFF_TEMPLATE_NAME);
   if (TREE_CODE (t) == TEMPLATE_DECL)
@@ -1495,6 +1496,10 @@  dump_function_decl (cxx_pretty_printer *pp, tree t
      emitting an error about incompatible specifications.  */
   exceptions = TYPE_RAISES_EXCEPTIONS (TREE_TYPE (t));
 
+  /* Likewise for the constexpr specifier, in case t is a specialization
+     and we are emitting an error about an incompatible redeclaration.  */
+  constexpr_p = DECL_DECLARED_CONSTEXPR_P (t);
+
   /* Pretty print template instantiations only.  */
   if (DECL_USE_TEMPLATE (t) && DECL_TEMPLATE_INFO (t)
       && flag_pretty_templates)
@@ -1529,7 +1534,7 @@  dump_function_decl (cxx_pretty_printer *pp, tree t
       else if (DECL_VIRTUAL_P (t))
 	pp_cxx_ws_string (pp, "virtual");
 
-      if (DECL_DECLARED_CONSTEXPR_P (t))
+      if (constexpr_p)
 	pp_cxx_ws_string (pp, "constexpr");
     }
 
Index: testsuite/g++.dg/cpp0x/constexpr-specialization.C
===================================================================
--- testsuite/g++.dg/cpp0x/constexpr-specialization.C	(revision 237472)
+++ testsuite/g++.dg/cpp0x/constexpr-specialization.C	(working copy)
@@ -3,10 +3,10 @@ 
 
 template<typename T> constexpr int foo(T);
 template<> int foo(int);
-template<> int foo(int);            // { dg-error "previous" }
-template<> constexpr int foo(int);  // { dg-error "redeclaration" }
+template<> int foo(int);            // { dg-message "previous declaration 'int foo" }
+template<> constexpr int foo(int);  // { dg-error "redeclaration 'constexpr int foo" }
 
 template<typename T> int bar(T);
 template<> constexpr int bar(int);
-template<> constexpr int bar(int);  // { dg-error "previous" }
-template<> int bar(int);            // { dg-error "redeclaration" }
+template<> constexpr int bar(int);  // { dg-message "previous declaration 'constexpr int bar" }
+template<> int bar(int);            // { dg-error "redeclaration 'int bar" }