Re: C, C++: Fix PR 69733 (bad location for ignored qualifiers warning)

[Bernd Schmidt <bschmidt at redhat dot com>]

On 04/25/2016 10:18 PM, Joseph Myers wrote:
> On Fri, 22 Apr 2016, Bernd Schmidt wrote:
>
> > +/* Returns the smallest location != UNKNOWN_LOCATION in LOCATIONS,
> > +   considering only those c_declspec_words found in LIST, which
> > +   must be terminated by cdw_number_of_elements.  */
> > +
> > +static location_t
> > +smallest_type_quals_location (const location_t* locations,
> > +			      c_declspec_word *list)
>
> I'd expect list to be a pointer to const...
>
> > @@ -6101,6 +6122,18 @@ grokdeclarator (const struct c_declarato
> >   	       qualify the return type, not the function type.  */
> >   	    if (type_quals)
> >   	      {
> > +		enum c_declspec_word ignored_quals_list[] =
> > +		  {
> > +		    cdw_const, cdw_volatile, cdw_restrict, cdw_address_space,
> > +		    cdw_number_of_elements
> > +		  };
>
>   ... and ignored_quals_list to be static const here.
How's this? Fully retested on x86_64-linux.


Bernd

c/
	PR c++/69733
	* c-decl.c (smallest_type_quals_location): New static function.
	(grokdeclarator): Try to find the correct location for an ignored
	qualifier.
cp/
	PR c++/69733
	* decl.c (grokdeclarator): Try to find the correct location for an
	ignored qualifier.
testsuite/
	PR c++/69733
	* c-c++-common/pr69733.c: New test.
	* gcc.target/i386/pr69733.c: New test.

Index: gcc/c/c-decl.c
===================================================================
--- gcc/c/c-decl.c	(revision 235808)
+++ gcc/c/c-decl.c	(working copy)
@@ -5321,6 +5321,27 @@ warn_defaults_to (location_t location, i
   va_end (ap);
 }
 
+/* Returns the smallest location != UNKNOWN_LOCATION in LOCATIONS,
+   considering only those c_declspec_words found in LIST, which
+   must be terminated by cdw_number_of_elements.  */
+
+static location_t
+smallest_type_quals_location (const location_t* locations,
+			      const c_declspec_word *list)
+{
+  location_t loc = UNKNOWN_LOCATION;
+  while (*list != cdw_number_of_elements)
+    {
+      location_t newloc = locations[*list];
+      if (loc == UNKNOWN_LOCATION
+	  || (newloc != UNKNOWN_LOCATION && newloc < loc))
+	loc = newloc;
+      list++;
+    }
+
+  return loc;
+}
+
 /* Given declspecs and a declarator,
    determine the name and type of the object declared
    and construct a ..._DECL node for it.
@@ -6142,6 +6163,18 @@ grokdeclarator (const struct c_declarato
 	       qualify the return type, not the function type.  */
 	    if (type_quals)
 	      {
+		const enum c_declspec_word ignored_quals_list[] =
+		  {
+		    cdw_const, cdw_volatile, cdw_restrict, cdw_address_space,
+		    cdw_number_of_elements
+		  };
+		location_t specs_loc
+		  = smallest_type_quals_location (declspecs->locations,
+						  ignored_quals_list);
+		if (specs_loc == UNKNOWN_LOCATION)
+		  specs_loc = declspecs->locations[cdw_typedef];
+		if (specs_loc == UNKNOWN_LOCATION)
+		  specs_loc = loc;
 		/* Type qualifiers on a function return type are
 		   normally permitted by the standard but have no
 		   effect, so give a warning at -Wreturn-type.
@@ -6149,10 +6182,10 @@ grokdeclarator (const struct c_declarato
 		   function definitions in ISO C; GCC used to used
 		   them for noreturn functions.  */
 		if (VOID_TYPE_P (type) && really_funcdef)
-		  pedwarn (loc, 0,
+		  pedwarn (specs_loc, 0,
 			   "function definition has qualified void return type");
 		else
-		  warning_at (loc, OPT_Wignored_qualifiers,
+		  warning_at (specs_loc, OPT_Wignored_qualifiers,
 			   "type qualifiers ignored on function return type");
 
 		type = c_build_qualified_type (type, type_quals);
Index: gcc/cp/decl.c
===================================================================
--- gcc/cp/decl.c	(revision 235808)
+++ gcc/cp/decl.c	(working copy)
@@ -10065,8 +10065,15 @@ grokdeclarator (const cp_declarator *dec
 	    if (type_quals != TYPE_UNQUALIFIED)
 	      {
 		if (SCALAR_TYPE_P (type) || VOID_TYPE_P (type))
-		  warning (OPT_Wignored_qualifiers,
-			   "type qualifiers ignored on function return type");
+		  {
+		    location_t loc;
+		    loc = smallest_type_quals_location (type_quals,
+							declspecs->locations);
+		    if (loc == UNKNOWN_LOCATION)
+		      loc = declspecs->locations[ds_type_spec];
+		    warning_at (loc, OPT_Wignored_qualifiers, "type "
+				"qualifiers ignored on function return type");
+		  }
 		/* We now know that the TYPE_QUALS don't apply to the
 		   decl, but to its return type.  */
 		type_quals = TYPE_UNQUALIFIED;
Index: gcc/testsuite/c-c++-common/pr69733.c
===================================================================
--- gcc/testsuite/c-c++-common/pr69733.c	(revision 0)
+++ gcc/testsuite/c-c++-common/pr69733.c	(working copy)
@@ -0,0 +1,24 @@
+/* { dg-do compile } */
+/* { dg-options "-W -fdiagnostics-show-caret" } */
+
+typedef const double cd;
+double val;
+
+const double val0() {return val;} /* { dg-warning "qualifiers ignored" } */
+/* { dg-begin-multiline-output "" }
+ const double val0() {return val;}
+ ^~~~~
+{ dg-end-multiline-output "" } */
+
+volatile double val1() {return val;} /* { dg-warning "qualifiers ignored" } */
+/* { dg-begin-multiline-output "" }
+ volatile double val1() {return val;}
+ ^~~~~~~~
+{ dg-end-multiline-output "" } */
+
+cd val2() {return val;} /* { dg-warning "qualifiers ignored" } */
+/* { dg-begin-multiline-output "" }
+ cd val2() {return val;}
+ ^~
+{ dg-end-multiline-output "" } */
+
Index: gcc/testsuite/gcc.target/i386/pr69733.c
===================================================================
--- gcc/testsuite/gcc.target/i386/pr69733.c	(revision 0)
+++ gcc/testsuite/gcc.target/i386/pr69733.c	(working copy)
@@ -0,0 +1,30 @@
+/* { dg-do compile } */
+/* { dg-options "-W -fdiagnostics-show-caret" } */
+
+typedef const double cd;
+double val;
+
+const double val0() {return val;} /* { dg-warning "qualifiers ignored" } */
+/* { dg-begin-multiline-output "" }
+ const double val0() {return val;}
+ ^~~~~
+{ dg-end-multiline-output "" } */
+
+volatile double val1() {return val;} /* { dg-warning "qualifiers ignored" } */
+/* { dg-begin-multiline-output "" }
+ volatile double val1() {return val;}
+ ^~~~~~~~
+{ dg-end-multiline-output "" } */
+
+cd val2() {return val;} /* { dg-warning "qualifiers ignored" } */
+/* { dg-begin-multiline-output "" }
+ cd val2() {return val;}
+ ^~
+{ dg-end-multiline-output "" } */
+
+__seg_fs int val3() {return val;} /* { dg-warning "qualifiers ignored" } */
+/* { dg-begin-multiline-output "" }
+ __seg_fs int val3() {return val;}
+ ^~~~~~~~
+{ dg-end-multiline-output "" } */
+