PR c/772

	PR c/17913
	* c-tree.h (C_DECL_UNJUMPABLE_STMT_EXPR,
	C_DECL_UNDEFINABLE_STMT_EXPR, struct c_label_list, struct
	c_label_context, label_context_stack): New.
	* c-decl.c (define_label): Check for jumps into statement
	expressions.  Add label to list of defined labels.
	(start_function): Push context on label_context_stack.
	(finish_function): Pop context from label_context_stack.
	* c-typeck.c (label_context_stack): New.
	(c_finish_goto_label): Check for jumps into statement
	expressions.  Add label to list of jumped to labels.
	(struct c_switch): Add blocked_stmt_expr.
	(c_start_case): Initialize it.
	(do_case): Check it.
	(c_finish_case): Verify !blocked_stmt_expr.
	(c_begin_stmt_expr):  Push context on label_context_stack.
	Increment blocked_stmt_expr.  Mark labels jumped to from outside
	as undefinable.
	(c_finish_stmt_expr): December blocked_stmt_expr.  Mark labels
	defined in the statement expression and no longer jumpable to.
	Mark labels jumped to from just outside the statement expression
	as again definable.  Pop context from label_context_stack.
	* doc/extend.texi (Statement Exprs): Update.

objc:
	* objc-act.c (objc_start_function): Push context on
	label_context_stack.

testsuite:
	* gcc.dg/stmt-expr-label-1.c, gcc.dg/stmt-expr-label-2.c,
	gcc.dg/stmt-expr-label-3.c : New tests.
	* gcc.c-torture/execute/medce-2.c: Remove.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@97273 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 17 insertions, 0 deletions

diff --git a/gcc/c-decl.c b/gcc/c-decl.c
index f333dade0b8..cb8fd9dfa2f 100644
--- a/gcc/c-decl.c
+++ b/gcc/c-decl.c
@@ -2440,6 +2440,7 @@ define_label (location_t location, tree name)
      if there is a containing function with a declared label with
      the same name.  */
   tree label = I_LABEL_DECL (name);
+  struct c_label_list *nlist;
 
   if (label
       && ((DECL_CONTEXT (label) == current_function_decl
@@ -2456,6 +2457,8 @@ define_label (location_t location, tree name)
       /* The label has been used or declared already in this function,
 	 but not defined.  Update its location to point to this
 	 definition.  */
+      if (C_DECL_UNDEFINABLE_STMT_EXPR (label))
+	error ("%Jjump into statement expression", label);
       DECL_SOURCE_LOCATION (label) = location;
     }
   else
@@ -2472,6 +2475,11 @@ define_label (location_t location, tree name)
     warning ("%Htraditional C lacks a separate namespace for labels, "
              "identifier %qE conflicts", &location, name);
 
+  nlist = XOBNEW (&parser_obstack, struct c_label_list);
+  nlist->next = label_context_stack->labels_def;
+  nlist->label = label;
+  label_context_stack->labels_def = nlist;
+
   /* Mark label as having been defined.  */
   DECL_INITIAL (label) = error_mark_node;
   return label;
@@ -5631,6 +5639,7 @@ start_function (struct c_declspecs *declspecs, struct c_declarator *declarator,
 {
   tree decl1, old_decl;
   tree restype, resdecl;
+  struct c_label_context *nstack;
 
   current_function_returns_value = 0;  /* Assume, until we see it does.  */
   current_function_returns_null = 0;
@@ -5639,6 +5648,12 @@ start_function (struct c_declspecs *declspecs, struct c_declarator *declarator,
   current_extern_inline = 0;
   c_switch_stack = NULL;
 
+  nstack = XOBNEW (&parser_obstack, struct c_label_context);
+  nstack->labels_def = NULL;
+  nstack->labels_used = NULL;
+  nstack->next = label_context_stack;
+  label_context_stack = nstack;
+
   /* Indicate no valid break/continue context by setting these variables
      to some non-null, non-label value.  We'll notice and emit the proper
      error message in c_finish_bc_stmt.  */
@@ -6220,6 +6235,8 @@ finish_function (void)
 {
   tree fndecl = current_function_decl;
 
+  label_context_stack = label_context_stack->next;
+
   if (TREE_CODE (fndecl) == FUNCTION_DECL
       && targetm.calls.promote_prototypes (TREE_TYPE (fndecl)))
     {