re PR c/30552 (gcc crashes when compiling examples with GNU statement…

re PR c/30552 (gcc crashes when compiling examples with GNU statement expressions in VLAs (also involved: nested functions declared K&R-style))

	PR c/30552
	* c-decl.c (old_style_parameter_scope): New function.
	* c-parser.c (c_parser_postfix_expression): Check for statement
	expressions in old-style function parameter list declarations.
	* c-parser.h (old_style_parameter_scope): New extern declaration.

	PR c/30552
	* gcc.dg/noncompile/pr30552-1.c: New test.
	* gcc.dg/noncompile/pr30552-2.c: New test.
	* gcc.dg/noncompile/pr30552-3.c: New test.
	* gcc.dg/noncompile/pr30552-4.c: New test.

From-SVN: r259849

gcc/c/ChangeLog

+2018-05-02  David Pagan  <dave.pagan@oracle.com>
+
+	PR c/30552
+	* c-decl.c (old_style_parameter_scope): New function.
+	* c-parser.c (c_parser_postfix_expression): Check for statement
+	expressions in old-style function parameter list declarations.
+	* c-parser.h (old_style_parameter_scope): New extern declaration.
+
 2018-04-25  Jakub Jelinek  <jakub@redhat.com>
 
 	PR sanitizer/84307

gcc/c/c-decl.c

@@ -952,6 +952,17 @@ global_bindings_p (void)
   return current_scope == file_scope;
 }
 
+/* Return true if we're declaring parameters in an old-style function
+   declaration.  */
+
+bool
+old_style_parameter_scope (void)
+{
+  /* If processing parameters and there is no function statement list, we
+   * have an old-style function declaration.  */
+  return (current_scope->parm_flag && !DECL_SAVED_TREE (current_function_decl));
+}
+
 void
 keep_next_level (void)
 {

gcc/c/c-parser.c

@@ -7930,7 +7930,10 @@ c_parser_postfix_expression (c_parser *parser)
 	  c_parser_consume_token (parser);
 	  brace_loc = c_parser_peek_token (parser)->location;
 	  c_parser_consume_token (parser);
-	  if (!building_stmt_list_p ())
+	  /* If we've not yet started the current function's statement list,
+	     or we're in the parameter scope of an old-style function
+	     declaration, statement expressions are not allowed.  */
+	  if (!building_stmt_list_p () || old_style_parameter_scope ())
 	    {
 	      error_at (loc, "braced-group within expression allowed "
 			"only inside a function");

gcc/c/c-parser.h

@@ -155,6 +155,9 @@ extern c_token * c_parser_tokens_buf (c_parser *parser, unsigned n);
 extern bool c_parser_error (c_parser *parser);
 extern void c_parser_set_error (c_parser *parser, bool);
 
+/* A bit of a hack to have this here.  It would be better in a c-decl.h.  */
+extern bool old_style_parameter_scope (void);
+
 /* Return true if the next token from PARSER has the indicated
    TYPE.  */
 

gcc/testsuite/ChangeLog

+2018-05-02  David Pagan  <dave.pagan@oracle.com>
+
+	PR c/30552
+	* gcc.dg/noncompile/pr30552-1.c: New test.
+	* gcc.dg/noncompile/pr30552-2.c: New test.
+	* gcc.dg/noncompile/pr30552-3.c: New test.
+	* gcc.dg/noncompile/pr30552-4.c: New test.
+
 2018-05-02  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/85597

gcc/testsuite/gcc.dg/noncompile/pr30552-1.c

+/* PR c/30552 */
+
+/* Statement expression as formal array argument size in nested old-style 
+   function declaration should generate user error, not internal compiler 
+   error.  */
+
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+int main()
+{
+  void fun(int a) /* { dg-error "old-style parameter declarations in prototyped function definition" } */
+    int a[({void h(){}2;})]; /* { dg-error "braced-group within expression allowed only inside a function" } */
+  {
+  }
+  return 0;
+}

gcc/testsuite/gcc.dg/noncompile/pr30552-2.c

+/* PR c/30552 */
+
+/* Another example of a statement expression as formal array argument size in
+ * nested old-style function declaration should generate user error, not 
+ * internal compiler error.  */
+
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+int main()
+{
+  void fun(a)
+    int a[({int b=2; b;})]; /* { dg-error "braced-group within expression allowed only inside a function" } */
+  {
+  }
+  return 0;
+}

gcc/testsuite/gcc.dg/noncompile/pr30552-3.c

+/* PR c/30552 */
+
+/* Related example where statement expression used as old-style formal array 
+ * argument size in an invalid nested function declaration should generate 
+ * user error, not internal compiler error. */
+
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+int main()
+{
+  int g()
+    int a[( {int b} )]; /* { dg-error "braced-group within expression allowed only inside a function|declaration for parameter" } */
+  return 0; /* { dg-error "expected declaration specifiers before" } */
+} /* { dg-error "expected declaration specifiers before|end of input|expected declaration or statement at end of input" } */

gcc/testsuite/gcc.dg/noncompile/pr30552-4.c

+/* PR c/30552 */
+
+/* Statement expression as formal array argument size in nested function
+ * prototype scope is valid.  */
+
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+int main()
+{
+  void fun(int a[({void h(){}10;})])
+  {
+  }
+  return 0;
+}