c-decl.c (diagnose_mismatched_decls): Give error for duplicate typedefs with…

c-decl.c (diagnose_mismatched_decls): Give error for duplicate typedefs with different but compatible types.

	* c-decl.c (diagnose_mismatched_decls): Give error for duplicate
	typedefs with different but compatible types.  Allow duplicate
	typedefs with the same type except for pedantic non-C1X, but give
	warning for variably modified types.
	* c-typeck.c (tagged_types_tu_compatible_p,
	function_types_compatible_p, type_lists_compatible_p,
	comptypes_internal): Add parameter different_types_p; set
	*different_types_p for different but compatible types.  All
	callers changed.
	(comptypes_check_different_types): New.
	* c-tree.h (comptypes_check_different_types): Declare.

testsuite:
	* gcc.dg/c1x-typedef-1.c, gcc.dg/c1x-typedef-2.c,
	gcc.dg/c90-typedef-1.c, gcc.dg/c99-typedef-1.c: New tests.
	* gcc.dg/decl-8.c: Use -std=gnu89 -pedantic-errors.

From-SVN: r159767

gcc/ChangeLog

+2010-05-23  Joseph Myers  <joseph@codesourcery.com>
+
+	* c-decl.c (diagnose_mismatched_decls): Give error for duplicate
+	typedefs with different but compatible types.  Allow duplicate
+	typedefs with the same type except for pedantic non-C1X, but give
+	warning for variably modified types.
+	* c-typeck.c (tagged_types_tu_compatible_p,
+	function_types_compatible_p, type_lists_compatible_p,
+	comptypes_internal): Add parameter different_types_p; set
+	*different_types_p for different but compatible types.  All
+	callers changed.
+	(comptypes_check_different_types): New.
+	* c-tree.h (comptypes_check_different_types): Declare.
+
 2010-05-23  Steven Bosscher  <steven@gcc.gnu.org>
 
 	* regs.h: Do not include obstack.h, basic-block.h.

gcc/c-decl.c

@@ -1786,18 +1786,48 @@ diagnose_mismatched_decls (tree newdecl, tree olddecl,
 
   /* Redeclaration of a type is a constraint violation (6.7.2.3p1),
      but silently ignore the redeclaration if either is in a system
-     header.  (Conflicting redeclarations were handled above.)  */
+     header.  (Conflicting redeclarations were handled above.)  This
+     is allowed for C1X if the types are the same, not just
+     compatible.  */
   if (TREE_CODE (newdecl) == TYPE_DECL)
     {
+      bool types_different = false;
+      int comptypes_result;
+
+      comptypes_result
+	= comptypes_check_different_types (oldtype, newtype, &types_different);
+
+      if (comptypes_result != 1 || types_different)
+	{
+	  error ("redefinition of typedef %q+D with different type", newdecl);
+	  locate_old_decl (olddecl);
+	  return false;
+	}
+
       if (DECL_IN_SYSTEM_HEADER (newdecl)
 	  || DECL_IN_SYSTEM_HEADER (olddecl)
 	  || TREE_NO_WARNING (newdecl)
 	  || TREE_NO_WARNING (olddecl))
 	return true;  /* Allow OLDDECL to continue in use.  */
 
-      error ("redefinition of typedef %q+D", newdecl);
-      locate_old_decl (olddecl);
-      return false;
+      if (pedantic && !flag_isoc1x)
+	{
+	  pedwarn (input_location, OPT_pedantic,
+		   "redefinition of typedef %q+D", newdecl);
+	  locate_old_decl (olddecl);
+	}
+      else if (variably_modified_type_p (newtype, NULL))
+	{
+	  /* Whether there is a constraint violation for the types not
+	     being the same cannot be determined at compile time; a
+	     warning that there may be one at runtime is considered
+	     appropriate (WG14 reflector message 11743, 8 May 2009).  */
+	  warning (0, "redefinition of typedef %q+D may be a constraint "
+		   "violation at runtime", newdecl);
+	  locate_old_decl (olddecl);
+	}
+
+      return true;
     }
 
   /* Function declarations can either be 'static' or 'extern' (no

gcc/c-tree.h

@@ -506,6 +506,7 @@ extern tree c_objc_common_truthvalue_conversion (location_t, tree);
 extern tree require_complete_type (tree);
 extern int same_translation_unit_p (const_tree, const_tree);
 extern int comptypes (tree, tree);
+extern int comptypes_check_different_types (tree, tree, bool *);
 extern bool c_vla_type_p (const_tree);
 extern bool c_mark_addressable (tree);
 extern void c_incomplete_type_error (const_tree, const_tree);

gcc/testsuite/ChangeLog

+2010-05-23  Joseph Myers  <joseph@codesourcery.com>
+
+	* gcc.dg/c1x-typedef-1.c, gcc.dg/c1x-typedef-2.c,
+	gcc.dg/c90-typedef-1.c, gcc.dg/c99-typedef-1.c: New tests.
+	* gcc.dg/decl-8.c: Use -std=gnu89 -pedantic-errors.
+
 2010-05-23  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* gcc.c-target/pr43869.c: Move "dg-do run" before lp64.

gcc/testsuite/gcc.dg/c1x-typedef-1.c

+/* Test typedef redeclaration in C1X.  */
+/* { dg-do compile } */
+/* { dg-options "-std=c1x -pedantic-errors" } */
+
+/* C1X permits typedefs to be redeclared to the same type, but not to
+   different-but-compatible types.  */
+
+#include <limits.h>
+
+typedef int TI;
+typedef int TI2;
+typedef TI2 TI;
+typedef TI TI2;
+
+enum e { E1 = 0, E2 = INT_MAX, E3 = -1 };
+typedef enum e TE;
+typedef enum e TE; /* { dg-message "previous declaration" } */
+typedef int TE; /* { dg-error "with different type" } */
+
+struct s;
+typedef struct s TS;
+struct s { int i; };
+typedef struct s TS;
+
+typedef int IA[];
+typedef TI2 IA[]; /* { dg-message "previous declaration" } */
+typedef int A2[2];
+typedef TI A2[2]; /* { dg-message "previous declaration" } */
+typedef IA A2; /* { dg-error "with different type" } */
+typedef int A3[3];
+typedef A3 IA; /* { dg-error "with different type" } */
+
+typedef void F(int);
+typedef void F(TI); /* { dg-message "previous declaration" } */
+typedef void F(enum e); /* { dg-error "with different type" } */
+
+typedef int G(void);
+typedef TI G(void); /* { dg-message "previous declaration" } */
+typedef enum e G(void); /* { dg-error "with different type" } */
+
+typedef int *P;
+typedef TI *P; /* { dg-message "previous declaration" } */
+typedef enum e *P; /* { dg-error "with different type" } */
+
+typedef void F2();
+typedef void F2(); /* { dg-message "previous declaration" } */
+typedef void F2(int); /* { dg-error "with different type" } */
+
+void
+f (void)
+{
+  int a = 1;
+  int b = 2;
+  typedef void FN(int (*p)[a]);
+  typedef void FN(int (*p)[b]);
+  typedef void FN(int (*p)[*]); /* { dg-message "previous declaration" } */
+  typedef void FN(int (*p)[1]); /* { dg-error "with different type" } */
+  typedef void FN2(int (*p)[a]);
+  typedef void FN2(int (*p)[b]);
+  typedef void FN2(int (*p)[*]); /* { dg-message "previous declaration" } */
+  typedef void FN2(int (*p)[]); /* { dg-error "with different type" } */
+  typedef int AV[a]; /* { dg-message "previous declaration" } */
+  typedef int AV[b-1]; /* { dg-warning "may be a constraint violation at runtime" } */
+  typedef int AAa[a];
+  typedef int AAb[b-1];
+  typedef AAa *VF(void); /* { dg-message "previous declaration" } */
+  typedef AAb *VF(void); /* { dg-warning "may be a constraint violation at runtime" } */
+}

gcc/testsuite/gcc.dg/c1x-typedef-2.c

+/* Test typedef redeclaration in C1X.  Side effects from duplicate
+   declarations still apply.  */
+/* { dg-do run } */
+/* { dg-options "-std=c1x -pedantic-errors" } */
+
+extern void exit (int);
+extern void abort (void);
+
+int
+main (void)
+{
+  int a = 1, b = 1;
+  typedef int T[++a]; /* { dg-message "previous declaration" } */
+  typedef int T[++b]; /* { dg-warning "may be a constraint violation at runtime" } */
+  if (a != 2 || b != 2)
+    abort ();
+  exit (0);
+}

gcc/testsuite/gcc.dg/c90-typedef-1.c

+/* Test typedef redeclaration not permitted in C90.  */
+/* { dg-do compile } */
+/* { dg-options "-std=iso9899:1990 -pedantic-errors" } */
+
+typedef int TI; /* { dg-message "previous declaration" } */
+typedef int TI; /* { dg-error "redefinition of typedef" } */

gcc/testsuite/gcc.dg/c99-typedef-1.c

+/* Test typedef redeclaration not permitted in C99.  */
+/* { dg-do compile } */
+/* { dg-options "-std=iso9899:1999 -pedantic-errors" } */
+
+typedef int TI; /* { dg-message "previous declaration" } */
+typedef int TI; /* { dg-error "redefinition of typedef" } */

gcc/testsuite/gcc.dg/decl-8.c

 /* Test diagnostics for duplicate typedefs.  Basic diagnostics.  */
 /* Origin: Joseph Myers <joseph@codesourcery.com> */
 /* { dg-do compile } */
-/* { dg-options "" } */
+/* { dg-options "-std=gnu89 -pedantic-errors" } */
 
 typedef int I; /* { dg-message "note: previous declaration of 'I' was here" } */
 typedef int I; /* { dg-error "redefinition of typedef 'I'" } */