re PR c/59905 (Unfriendly abort when calling a fucntion via a function pointer cast)

2014-01-30  Richard Biener  <rguenther@suse.de>

	PR c/59905
	* c-typeck.c (build_function_call_vec): Do not replace calls
	to a function via an incompatible type with a runtime abort.

	* gcc.dg/cast-function-1.c: Adjust to survive DCE.
	* gcc.dg/call-diag-2.c: Remove expected warnings about calling
	abort.
	* gcc.dg/invalid-call-1.c: Likewise.

From-SVN: r207300

gcc/c/ChangeLog

+2014-01-30  Richard Biener  <rguenther@suse.de>
+
+	PR c/59905
+	* c-typeck.c (build_function_call_vec): Do not replace calls
+	to a function via an incompatible type with a runtime abort.
+
 2014-01-24  Balaji V. Iyer  <balaji.v.iyer@intel.com>
 
 	* c-parser.c (c_parser_declaration_or_fndef): Replaced

gcc/c/c-typeck.c

@@ -2907,55 +2907,23 @@ build_function_call_vec (location_t loc, tree function,
     return error_mark_node;
 
   /* Check that the function is called through a compatible prototype.
-     If it is not, replace the call by a trap, wrapped up in a compound
-     expression if necessary.  This has the nice side-effect to prevent
-     the tree-inliner from generating invalid assignment trees which may
-     blow up in the RTL expander later.  */
+     If it is not, warn.  */
   if (CONVERT_EXPR_P (function)
       && TREE_CODE (tem = TREE_OPERAND (function, 0)) == ADDR_EXPR
       && TREE_CODE (tem = TREE_OPERAND (tem, 0)) == FUNCTION_DECL
       && !comptypes (fntype, TREE_TYPE (tem)))
     {
       tree return_type = TREE_TYPE (fntype);
-      tree trap = build_function_call (loc,
-				       builtin_decl_explicit (BUILT_IN_TRAP),
-				       NULL_TREE);
-      int i;
 
       /* This situation leads to run-time undefined behavior.  We can't,
 	 therefore, simply error unless we can prove that all possible
 	 executions of the program must execute the code.  */
-      if (warning_at (loc, 0, "function called through a non-compatible type"))
-	/* We can, however, treat "undefined" any way we please.
-	   Call abort to encourage the user to fix the program.  */
-	inform (loc, "if this code is reached, the program will abort");
-      /* Before the abort, allow the function arguments to exit or
-	 call longjmp.  */
-      for (i = 0; i < nargs; i++)
-	trap = build2 (COMPOUND_EXPR, void_type_node, (*params)[i], trap);
-
-      if (VOID_TYPE_P (return_type))
-	{
-	  if (TYPE_QUALS (return_type) != TYPE_UNQUALIFIED)
+      warning_at (loc, 0, "function called through a non-compatible type");
+
+      if (VOID_TYPE_P (return_type)
+	  && TYPE_QUALS (return_type) != TYPE_UNQUALIFIED)
 	pedwarn (loc, 0,
 		 "function with qualified void return type called");
-	  return trap;
-	}
-      else
-	{
-	  tree rhs;
-
-	  if (AGGREGATE_TYPE_P (return_type))
-	    rhs = build_compound_literal (loc, return_type,
-					  build_constructor (return_type,
-					    NULL),
-					  false);
-	  else
-	    rhs = build_zero_cst (return_type);
-
-	  return require_complete_type (build2 (COMPOUND_EXPR, return_type,
-						trap, rhs));
-	}
      }
 
   argarray = vec_safe_address (params);

gcc/testsuite/ChangeLog

+2014-01-30  Richard Biener  <rguenther@suse.de>
+
+	PR c/59905
+	* gcc.dg/cast-function-1.c: Adjust to survive DCE.
+	* gcc.dg/call-diag-2.c: Remove expected warnings about calling
+	abort.
+	* gcc.dg/invalid-call-1.c: Likewise.
+
 2014-01-29  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/58561

gcc/testsuite/gcc.dg/call-diag-2.c

@@ -11,7 +11,5 @@ void g1 (void) { f_cv (); } /* { dg-error "qualified void" } */
 void g2 (void) { f_s (); } /* { dg-error "invalid use of undefined type" } */
 void g3 (void) { ((const void (*) (void)) f_v) (); } /* { dg-error "qualified void" } */
 /* { dg-warning "function called through a non-compatible type" "cast" { target *-*-* } 12 } */
-/* { dg-message "will abort" "abort" { target *-*-* } 12 } */
 void g4 (void) { ((struct s (*) (void)) f_v) (), (void) 0; } /* { dg-error "invalid use of undefined type" } */
-/* { dg-warning "function called through a non-compatible type" "cast" { target *-*-* } 15 } */
-/* { dg-message "will abort" "abort" { target *-*-* } 15 } */
+/* { dg-warning "function called through a non-compatible type" "cast" { target *-*-* } 14 } */

gcc/testsuite/gcc.dg/cast-function-1.c

@@ -16,12 +16,8 @@ typedef struct {
   int a;
 } str_t;
 
-void bar(void)
+void bar(double d, int i, str_t s)
 {
-  double d;
-  int i;
-  str_t s;
-
   d = ((double (*) (int)) foo1) (i);  /* { dg-warning "33:non-compatible|abort" } */
   i = ((int (*) (double)) foo1) (d);  /* { dg-warning "33:non-compatible|abort" } */
   s = ((str_t (*) (int)) foo1) (i);   /* { dg-warning "32:non-compatible|abort" } */
@@ -39,11 +35,15 @@ void bar(void)
 
 int foo1(int arg)
 {
+  /* Prevent the function from becoming const and thus DCEd.  */
+  __asm volatile ("" : "+r" (arg));
   return arg;
 }
 
 int foo2(arg)
   int arg;
 {
+  /* Prevent the function from becoming const and thus DCEd.  */
+  __asm volatile ("" : "+r" (arg));
   return arg;
 }

gcc/testsuite/gcc.dg/invalid-call-1.c

@@ -14,5 +14,4 @@ void foo()
 {
   cptr = mar(6);
   ((char *(*)(void *,int (*)(void *,unsigned char **),char**))((fp)bar))(0,0,(void*)(0)); /* { dg-warning "function called through a non-compatible type" "non-compatible type" } */
-  /* { dg-message "note: if this code is reached, the program will abort" "" { target *-*-* } 16 } */
 }