Re: [PATCH] c: Diagnose compound literals with function type [PR108043]

[Marek Polacek <polacek@redhat.com>]

On Mon, Dec 19, 2022 at 12:05:48PM +0100, Jakub Jelinek wrote:
> Hi!
> 
> Both C99 and latest C2X say that compound literal shall have an object type
> (complete object type in the latter case) or array of unknown bound,
> so complit with function type is invalid.  When the initializer had to be
> non-empty for such case, we used to diagnose it as incorrect initializer,
> but with (fntype){} now allowed we just ICE on it.
> 
> The following patch diagnoses that.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

This looks OK to me, thanks.
 
> 2022-12-19  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR c/108043
> 	* c-parser.cc (c_parser_postfix_expression_after_paren_type): Diagnose
> 	compound literals with function type.
> 
> 	* gcc.dg/pr108043.c: New test.
> 	* gcc.dg/c99-complit-2.c (foo): Adjust expected diagnostics for
> 	complit with function type.
> 
> --- gcc/c/c-parser.cc.jj	2022-11-18 09:00:44.331323558 +0100
> +++ gcc/c/c-parser.cc	2022-12-16 13:08:51.143083269 +0100
> @@ -10924,6 +10924,11 @@ c_parser_postfix_expression_after_paren_
>        error_at (type_loc, "compound literal has variable size");
>        type = error_mark_node;
>      }
> +  else if (TREE_CODE (type) == FUNCTION_TYPE)
> +    {
> +      error_at (type_loc, "compound literal has function type");
> +      type = error_mark_node;
> +    }
>    if (constexpr_p && type != error_mark_node)
>      {
>        tree type_no_array = strip_array_types (type);
> --- gcc/testsuite/gcc.dg/pr108043.c.jj	2022-12-16 13:15:40.122083457 +0100
> +++ gcc/testsuite/gcc.dg/pr108043.c	2022-12-16 13:15:20.840366320 +0100
> @@ -0,0 +1,12 @@
> +/* PR c/108043 */
> +/* { dg-do compile } */
> +/* { dg-options "" } */
> +
> +typedef void F (void);
> +
> +void
> +foo (void)
> +{
> +  (F) {};		/* { dg-error "compound literal has function type" } */
> +  (F) { foo };		/* { dg-error "compound literal has function type" } */
> +}
> --- gcc/testsuite/gcc.dg/c99-complit-2.c.jj	2020-01-12 11:54:37.393398623 +0100
> +++ gcc/testsuite/gcc.dg/c99-complit-2.c	2022-12-19 11:51:45.098467295 +0100
> @@ -23,7 +23,7 @@ foo (int a)
>    /* { dg-error "init" "incomplete union type" { target *-*-* } .-1 } */
>    /* { dg-error "invalid use of undefined type" "" { target *-*-* } .-2 } */
>    (void (void)) { 0 }; /* { dg-bogus "warning" "warning in place of error" } */
> -  /* { dg-error "init" "function type" { target *-*-* } .-1 } */
> +  /* { dg-error "compound literal has function type" "function type" { target *-*-* } .-1 } */
>    (int [a]) { 1 }; /* { dg-bogus "warning" "warning in place of error" } */
>    /* { dg-error "init|variable" "VLA type" { target *-*-* } .-1 } */
>    /* Initializers must not attempt to initialize outside the object
> 
> 	Jakub
> 

Marek