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

1 files changed, 31 insertions, 0 deletions

diff --git a/gcc/c-decl.c b/gcc/c-decl.c
index af6a2c0..746fa47 100644
--- a/gcc/c-decl.c
+++ b/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;