c-decl.c (finish_function): Warn about a non-void function with no return statement and no abnormal exit.

* c-decl.c (finish_function): Warn about a non-void function with
        no return statement and no abnormal exit.
        (current_function_returns_abnormally): New variable.
        (start_function): Clear it.
        (struct c_language_function): Add returns_abnormally.
        (push_c_function_context): Save it.
        (pop_c_function_context): Restore it.
        (builtin_function): Set TREE_THIS_VOLATILE on return fns.
        (grokdeclarator): Set C_FUNCTION_IMPLICIT_INT on functions without
        an explicit return type.
        * c-tree.h: Declare current_function_returns_abnormally.
        (C_FUNCTION_IMPLICIT_INT): New macro.
        * c-typeck.c (build_function_call): Set it.
        (c_expand_return): Set current_function_returns_value even if the
        value is erroneous.

From-SVN: r49551

gcc/ChangeLog

@@ -1,3 +1,21 @@
+2002-02-06  Jason Merrill  <jason@redhat.com>
+
+	* c-decl.c (finish_function): Warn about a non-void function with
+	no return statement and no abnormal exit.
+	(current_function_returns_abnormally): New variable.
+	(start_function): Clear it.
+	(struct c_language_function): Add returns_abnormally.
+	(push_c_function_context): Save it.
+	(pop_c_function_context): Restore it.
+	(builtin_function): Set TREE_THIS_VOLATILE on return fns.
+	(grokdeclarator): Set C_FUNCTION_IMPLICIT_INT on functions without
+	an explicit return type.
+	* c-tree.h: Declare current_function_returns_abnormally.
+	(C_FUNCTION_IMPLICIT_INT): New macro.
+	* c-typeck.c (build_function_call): Set it.
+	(c_expand_return): Set current_function_returns_value even if the
+	value is erroneous.
+
 2002-02-06  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c/5420:

gcc/c-decl.c

@@ -134,6 +134,11 @@ int current_function_returns_value;
 
 int current_function_returns_null;
 
+/* Set to 0 at beginning of a function definition, set to 1 if
+   a call to a noreturn function is seen.  */
+
+int current_function_returns_abnormally;
+
 /* Set to nonzero by `grokdeclarator' for a function
    whose return type is defaulted, if warnings for this are desired.  */
 
@@ -3214,6 +3219,10 @@ builtin_function (name, type, function_code, class, library_name)
   DECL_BUILT_IN_CLASS (decl) = class;
   DECL_FUNCTION_CODE (decl) = function_code;
 
+  /* The return builtins leave the current function.  */
+  if (function_code == BUILT_IN_RETURN || function_code == BUILT_IN_EH_RETURN)
+    TREE_THIS_VOLATILE (decl) = 1;
+
   /* Warn if a function in the namespace for users
      is used without an occasion to consider it declared.  */
   if (name[0] != '_' || name[1] != '_')
@@ -5086,6 +5095,9 @@ grokdeclarator (declarator, declspecs, decl_context, initialized)
 	TREE_PUBLIC (decl)
 	  = !(specbits & ((1 << (int) RID_STATIC) | (1 << (int) RID_AUTO)));
 
+	if (defaulted_int)
+	  C_FUNCTION_IMPLICIT_INT (decl) = 1;
+
 	/* Record presence of `inline', if it is reasonable.  */
 	if (MAIN_NAME_P (declarator))
 	  {
@@ -6175,6 +6187,7 @@ start_function (declspecs, declarator, attributes)
 
   current_function_returns_value = 0;  /* Assume, until we see it does.  */
   current_function_returns_null = 0;
+  current_function_returns_abnormally = 0;
   warn_about_return_type = 0;
   current_extern_inline = 0;
   c_function_varargs = 0;
@@ -6904,6 +6917,21 @@ finish_function (nested)
 
   /* Tie off the statement tree for this function.  */
   finish_stmt_tree (&DECL_SAVED_TREE (fndecl));
+
+  /* Complain if there's just no return statement.  */
+  if (TREE_CODE (TREE_TYPE (TREE_TYPE (fndecl))) != VOID_TYPE
+      && !current_function_returns_value && !current_function_returns_null
+      /* Don't complain if we abort.  */
+      && !current_function_returns_abnormally
+      /* Don't warn for main().  */
+      && !MAIN_NAME_P (DECL_NAME (fndecl))
+      /* Or if they didn't actually specify a return type.  */
+      && !C_FUNCTION_IMPLICIT_INT (fndecl)
+      /* If we have -Wreturn-type, let flow complain.  Unless we're an
+	 inline function, as we might never be compiled separately.  */
+      && (!warn_return_type || DECL_INLINE (fndecl)))
+    warning ("no return statement in function returning non-void");
+
   /* Clear out memory we no longer need.  */
   free_after_parsing (cfun);
   /* Since we never call rest_of_compilation, we never clear
@@ -7193,6 +7221,7 @@ struct c_language_function
   tree shadowed_labels;
   int returns_value;
   int returns_null;
+  int returns_abnormally;
   int warn_about_return_type;
   int extern_inline;
   struct binding_level *binding_level;
@@ -7216,6 +7245,7 @@ push_c_function_context (f)
   p->shadowed_labels = shadowed_labels;
   p->returns_value = current_function_returns_value;
   p->returns_null = current_function_returns_null;
+  p->returns_abnormally = current_function_returns_abnormally;
   p->warn_about_return_type = warn_about_return_type;
   p->extern_inline = current_extern_inline;
   p->binding_level = current_binding_level;
@@ -7253,6 +7283,7 @@ pop_c_function_context (f)
   shadowed_labels = p->shadowed_labels;
   current_function_returns_value = p->returns_value;
   current_function_returns_null = p->returns_null;
+  current_function_returns_abnormally = p->returns_abnormally;
   warn_about_return_type = p->warn_about_return_type;
   current_extern_inline = p->extern_inline;
   current_binding_level = p->binding_level;

gcc/c-tree.h

@@ -132,6 +132,10 @@ struct lang_type
 /* Record whether a typedef for type `int' was actually `signed int'.  */
 #define C_TYPEDEF_EXPLICITLY_SIGNED(EXP) DECL_LANG_FLAG_1 (EXP)
 
+/* For a FUNCTION_DECL, nonzero if it was defined without an explicit
+   return type.  */
+#define C_FUNCTION_IMPLICIT_INT(EXP) DECL_LANG_FLAG_1 (EXP)
+
 /* Nonzero for a declaration of a built in function if there has been no
    occasion that would declare the function in ordinary C.
    Using the function draws a pedantic warning in this case.  */
@@ -277,6 +281,11 @@ extern int current_function_returns_value;
 
 extern int current_function_returns_null;
 
+/* Set to 0 at beginning of a function definition, set to 1 if
+   a call to a noreturn function is seen.  */
+
+extern int current_function_returns_abnormally;
+
 /* Nonzero means the expression being parsed will never be evaluated.
    This is a count, since unevaluated expressions can nest.  */
 

gcc/c-typeck.c

@@ -1547,6 +1547,9 @@ build_function_call (function, params)
       return error_mark_node;
     }
 
+  if (fundecl && TREE_THIS_VOLATILE (fundecl))
+    current_function_returns_abnormally = 1;
+
   /* fntype now gets the type of function pointed to.  */
   fntype = TREE_TYPE (fntype);
 
@@ -7084,6 +7087,7 @@ c_expand_return (retval)
       tree res = DECL_RESULT (current_function_decl);
       tree inner;
 
+      current_function_returns_value = 1;
       if (t == error_mark_node)
 	return NULL_TREE;
 
@@ -7141,7 +7145,6 @@ c_expand_return (retval)
 	}
 
       retval = build (MODIFY_EXPR, TREE_TYPE (res), res, t);
-      current_function_returns_value = 1;
     }
 
  return add_stmt (build_return_stmt (retval));

gcc/testsuite/gcc.dg/20011029-2.c

@@ -20,4 +20,5 @@ int foo (int s)
 					: "cc"); r; }))
         continue;
     }
+  return 0;
 }

gcc/testsuite/gcc.dg/980816-1.c

@@ -17,4 +17,5 @@ div_and_round_double (lden_orig, hden_orig)
       quo[i] = work / (unsigned int ) lden;
       carry = work % (unsigned int ) lden;
     }
+  return 0;
 }

gcc/testsuite/gcc.dg/990117-1.c

@@ -18,4 +18,5 @@ foo ()
   for (i = 0; i < 10; i++)
     ;
   fabs (x - y);
+  return 0;
 }

gcc/testsuite/gcc.dg/990213-2.c

@@ -12,4 +12,5 @@ XmlInitUnknownEncoding(void *mem)
   struct unknown_encoding *e = mem;
   for (i = 0; i < sizeof(struct normal_encoding); i++)
     ((char *)mem)[i] = ((char *)&latin1_encoding)[i];
+  return 0;
 }

gcc/testsuite/gcc.dg/990214-1.c

@@ -12,4 +12,6 @@ bar (int64_t which)
 	case 5 :
 	case 2 : ;
 	}
+
+	return 0;
 }

gcc/testsuite/gcc.dg/990524-1.c

@@ -34,5 +34,5 @@ p_frames_to_multilayer(t_anim_info *ainfo_ptr,
        break;
     l_cur_frame_nr += l_step;
   }
+  return 0;
 }
-

gcc/testsuite/gcc.dg/991214-1.c

@@ -3,8 +3,8 @@
 
 /* Test against a problem with the combiner substituting explicit hard reg
    references when it shouldn't.  */
-int foo (int, int) __attribute__ ((regparm (3)));
-int foo (int x, int y)
+void foo (int, int) __attribute__ ((regparm (3)));
+void foo (int x, int y)
 {
   __asm__ __volatile__("" : : "d" (x), "r" (y));
 }

gcc/testsuite/gcc.dg/asm-2.c

@@ -1,7 +1,7 @@
 /* { dg-do compile } */
 /* { dg-options "" } */
 
-int f()
+void f()
 {
   asm volatile ("foo%%bar" : : );
 }

gcc/testsuite/gcc.dg/asm-3.c

@@ -1,7 +1,7 @@
 /* { dg-do compile } */
 /* { dg-options "" } */
 
-int f()
+void f()
 {
   asm ("foo%%bar");
 }

gcc/testsuite/gcc.dg/attr-invalid.c

@@ -21,13 +21,14 @@ int ATSYM(var) ATTR;  /* { dg-warning "attribute ignored" "" } */
 
 int ATSYM(fn_knrarg) (arg)
   int arg ATTR; /* { dg-warning "attribute ignored" "" } */
-{}
+{ return 0; }
 
-int ATSYM(fn_isoarg) (int arg ATTR) {} /* { dg-warning "attribute ignored" "" } */
+int ATSYM(fn_isoarg) (int arg ATTR) { return 0; } /* { dg-warning "attribute ignored" "" } */
 
 int ATSYM(fn_vars) (void) {
   static int svar ATTR; /* { dg-warning "attribute ignored" "" } */
   auto int lvar ATTR; /* { dg-warning "attribute ignored" "" } */
+  return 0;
 }
 
 
@@ -46,11 +47,12 @@ int ATSYM(var) ATTR;  /* { dg-warning "attribute ignored" "" } */
 
 int ATSYM(fn_knrarg) (arg)
   int arg ATTR; /* { dg-warning "attribute ignored" "" } */
-{}
+{ return 0; }
 
-int ATSYM(fn_isoarg) (int arg ATTR) {} /* { dg-warning "attribute ignored" "" } */
+int ATSYM(fn_isoarg) (int arg ATTR) { return 0; } /* { dg-warning "attribute ignored" "" } */
 
 int ATSYM(fn_vars) (void) {
   static int svar ATTR; /* { dg-warning "attribute ignored" "" } */
   auto int lvar ATTR; /* { dg-warning "attribute ignored" "" } */
+  return 0;
 }

gcc/testsuite/gcc.dg/attr-noinline.c

@@ -43,7 +43,7 @@ static inline void function_declaration_noinline_inline_before(void); /* { dg-wa
 
 static void function_declaration_noinline_inline_before(void) {}
 
-int f () {
+void f () {
   function_definition ();
   function_declaration_both_before ();
   function_declaration_both_after ();

gcc/testsuite/gcc.dg/deprecated.c

@@ -13,10 +13,10 @@ INT1 should_be_unavailable; 		/* { dg-warning "`INT1' is deprecated" "" } */
 INT1a should_not_be_deprecated;
 
 INT1 f1(void) __attribute__ ((deprecated)); 
-INT1 f2(void) {}			/* { dg-warning "`INT1' is deprecated" "" } */
+INT1 f2(void) { return 0; }		/* { dg-warning "`INT1' is deprecated" "" } */
 
 INT2 f3(void) __attribute__ ((__deprecated__)); 
-INT2 f4(void) {}			/* { dg-warning "`INT2' is deprecated" "" } */
+INT2 f4(void) { return 0; }		/* { dg-warning "`INT2' is deprecated" "" } */
 int f5(INT2 x);				/* { dg-warning "`INT2' is deprecated" "" } */
 int f6(INT2 x) __attribute__ ((__deprecated__)); /* { dg-warning "`INT2' is deprecated" "" } */
 

gcc/testsuite/gcc.dg/struct-ret-2.c

@@ -4,7 +4,7 @@
    Copyright (C) 1999 Free Software Foundation  */
 
 /* { dg-do compile } */
-/* { dg-options "-O3" } */
+/* { dg-options "-O3 -w" } */
 
 struct {
   unsigned i[4];

gcc/testsuite/gcc.misc-tests/bprob-1.c

@@ -68,7 +68,7 @@ test_for2 (int m, int n, int o)
   return for_temp;			/* count(6) */
 }
 
-int
+void
 call_for ()
 {
   for_val1 += test_for1 (0);

gcc/testsuite/gcc.misc-tests/gcov-4.c

@@ -68,7 +68,7 @@ test_for2 (int m, int n, int o)
   return for_temp;			/* count(6) */
 }
 
-int
+void
 call_for ()
 {
   for_val1 += test_for1 (0);

gcc/testsuite/gcc.misc-tests/gcov-4b.c

@@ -41,7 +41,7 @@ test_for2 (int m, int n, int o)
   return for_temp;
 }
 
-int
+void
 call_for ()
 {
   for_val1 += test_for1 (0);