re PR c/53066 (Wshadow should not warn for shadowing an extern function)

2012-10-29  Manuel López-Ibáñez  <manu@gcc.gnu.org>

	PR c/53066
c/
	* c-decl.c (warn_if_shadowing): Do not warn if a variable
	shadows a function, unless the variable is a function or a
	pointer-to-function.
gcc/
	* tree.h (FUNCTION_POINTER_TYPE_P): New.
testsuite/
	* gcc.dg/Wshadow-4.c: New.
	* gcc.dg/Wshadow-4.h: New.

From-SVN: r192963

7 files changed, 75 insertions, 2 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 0b2a3be..574a474 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2012-10-29  Manuel López-Ibáñez  <manu@gcc.gnu.org>
+
+	PR c/53066
+	* tree.h (FUNCTION_POINTER_TYPE_P): New.
+
 2012-10-29  Alexandre Oliva <aoliva@redhat.com>
 
 	PR debug/54693
diff --git a/gcc/c/ChangeLog b/gcc/c/ChangeLog
index 89d89f7..f44131b 100644
--- a/gcc/c/ChangeLog
+++ b/gcc/c/ChangeLog
@@ -1,3 +1,10 @@
+2012-10-29  Manuel López-Ibáñez  <manu@gcc.gnu.org>
+
+	PR c/53066
+	* c-decl.c (warn_if_shadowing): Do not warn if a variable
+	shadows a function, unless the variable is a function or a
+	pointer-to-function.
+
 2012-10-12  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c/54381
diff --git a/gcc/c/c-decl.c b/gcc/c/c-decl.c
index 80867ca..f031466 100644
--- a/gcc/c/c-decl.c
+++ b/gcc/c/c-decl.c
@@ -2561,8 +2561,18 @@ warn_if_shadowing (tree new_decl)
 	  warning (OPT_Wshadow, "declaration of %q+D shadows a parameter",
 		   new_decl);
 	else if (DECL_FILE_SCOPE_P (old_decl))
-	  warning (OPT_Wshadow, "declaration of %q+D shadows a global "
-		   "declaration", new_decl);
+	  {
+	    /* Do not warn if a variable shadows a function, unless
+	       the variable is a function or a pointer-to-function.  */
+	    if (TREE_CODE (old_decl) == FUNCTION_DECL
+		&& TREE_CODE (new_decl) != FUNCTION_DECL
+		&& !FUNCTION_POINTER_TYPE_P (TREE_TYPE (new_decl)))
+		continue;
+
+	    warning_at (DECL_SOURCE_LOCATION (new_decl), OPT_Wshadow, 
+			"declaration of %qD shadows a global declaration",
+			new_decl);
+	  }
 	else if (TREE_CODE (old_decl) == FUNCTION_DECL
 		 && DECL_BUILT_IN (old_decl))
 	  {
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index c6899df..49d6b9d 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2012-10-29  Manuel López-Ibáñez  <manu@gcc.gnu.org>
+
+	PR c/53066
+	* gcc.dg/Wshadow-4.c: New.
+	* gcc.dg/Wshadow-4.h: New.
+
 2012-10-29  Alexandre Oliva <aoliva@redhat.com>
 
 	PR debug/54693
diff --git a/gcc/testsuite/gcc.dg/Wshadow-4.c b/gcc/testsuite/gcc.dg/Wshadow-4.c
new file mode 100644
index 0000000..f3b986f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/Wshadow-4.c
@@ -0,0 +1,38 @@
+/* { dg-do compile } */
+/* { dg-options "-Wshadow -Wsystem-headers" } */
+
+#include "Wshadow-4.h"
+extern void index2 (void); /* { dg-message "declaration is here" } */
+
+void foo (double index1,
+	  double index2)
+{
+}
+
+void foo1 (void)
+{
+  double index1;
+  double index2;
+}
+
+void foo2 (void)
+{
+  {
+    double index1;
+    double index2;
+  }
+}
+
+void foo3 (void)
+{
+  void (*index1)(void); /* { dg-warning "shadows" } */
+  void (*index2)(void); /* { dg-warning "shadows" } */
+}
+
+void foo4 (void)
+{
+  void index1(void) {}; /* { dg-warning "shadows" } */
+  void index2(void) {}; /* { dg-warning "shadows" } */
+}
+
+/* { dg-message "declaration is here" "" { target *-*-* } 0 } */
diff --git a/gcc/testsuite/gcc.dg/Wshadow-4.h b/gcc/testsuite/gcc.dg/Wshadow-4.h
new file mode 100644
index 0000000..5a44ca4
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/Wshadow-4.h
@@ -0,0 +1,3 @@
+#pragma GCC system_header
+extern void index1 (void);
+
diff --git a/gcc/tree.h b/gcc/tree.h
index c6a5eab..d921886 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -1066,6 +1066,10 @@ extern void omp_clause_range_check_failed (const_tree, const char *, int,
 #define POINTER_TYPE_P(TYPE) \
   (TREE_CODE (TYPE) == POINTER_TYPE || TREE_CODE (TYPE) == REFERENCE_TYPE)
 
+/* Nonzero if TYPE represents a pointer to function.  */
+#define FUNCTION_POINTER_TYPE_P(TYPE) \
+  (POINTER_TYPE_P (TYPE) && TREE_CODE (TREE_TYPE (TYPE)) == FUNCTION_TYPE)
+
 /* Nonzero if this type is a complete type.  */
 #define COMPLETE_TYPE_P(NODE) (TYPE_SIZE (NODE) != NULL_TREE)