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

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

[Jakub Jelinek]

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?

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

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

[Marek Polacek]

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