c: ignore initializers for elements of variable-size types [PR93577]

[Christophe Lyon]

On Wed, 11 Mar 2020 at 00:37, Joseph Myers <joseph@codesourcery.com> wrote:
>
> On Tue, 10 Mar 2020, Christophe Lyon wrote:
>
> > sizeless-1.c and sizeless-2.c have the same code, but the latter is
> > compiled with -msve-vector-bits=256 and expects different
> > warnings/errors.
> > For line 33:
> > svint8_t *invalid_sve_sc_ptr = &(svint8_t) { *global_sve_sc_ptr };
> > we now have:
> > sizeless-1.c:33:44: error: empty scalar initializer
> > sizeless-1.c:33:44: note: (near initialization for '(anonymous)')
> > and
> > sizeless-2.c:33:44: error: initializer element is not constant
> > sizeless-2.c:33:44: note: (near initialization for 'invalid_sve_sc_ptr')
> > sizeless-2.c:33:44: error: SVE type 'svint8_t' does not have a fixed size
> > so I think the error comes from the compound literal being treated
> > differently with -msve-vector-bits=256
>
> I think the sizeless-2.c diagnostics are correct while there's a problem
> in the sizeless-1.c case (the initializer is not empty, so it should not
> be diagnosed as such).
>
> Does the process_init_element code
>
>   /* Ignore elements of an initializer for a variable-size type.
>      Those are diagnosed in digest_init.  */
>   if (COMPLETE_TYPE_P (constructor_type)
>       && TREE_CODE (TYPE_SIZE (constructor_type)) != INTEGER_CST)
>     return;
>
> fire for the sizeless-1.c case?  If so, maybe it needs to be restricted in
> some way to apply only to variable size structs / unions / arrays rather
> than whatever kind of variable-size type the SVE types are.

It does. Type_size has POLY_INT_CST type.

The attached small patch fixes the problem (tested on arm and aarch64).
OK?

gcc/c/ChangeLog:

2020-03-13  Christophe Lyon  <christophe.lyon@linaro.org>

        * c-typeck.c (process_init_element): Handle constructor_type with
        type size represented by POLY_INT_CST.

gcc/testsuite/ChangeLog:

2020-03-13  Christophe Lyon  <christophe.lyon@linaro.org>

        * gcc.target/aarch64/sve/acle/general-c/sizeless-1.c: Remove
        superfluous dg-error.
        * gcc.target/aarch64/sve/acle/general-c/sizeless-2.c: Likewise.


diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c
index d8025de..1302486 100644
--- a/gcc/c/c-typeck.c
+++ b/gcc/c/c-typeck.c
@@ -9968,7 +9968,8 @@ process_init_element (location_t loc, struct
c_expr value, bool implicit,
   /* Ignore elements of an initializer for a variable-size type.
      Those are diagnosed in digest_init.  */
   if (COMPLETE_TYPE_P (constructor_type)
-      && TREE_CODE (TYPE_SIZE (constructor_type)) != INTEGER_CST)
+      && TREE_CODE (TYPE_SIZE (constructor_type)) != INTEGER_CST
+      && TREE_CODE (TYPE_SIZE (constructor_type)) != POLY_INT_CST)
     return;

   if (!implicit && warn_designated_init && !was_designated
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/sizeless-1.c
b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/sizeless-1.c
index ec892a3..e53b871 100644
--- a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/sizeless-1.c
+++ b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/sizeless-1.c
@@ -83,7 +83,6 @@ statements (int n)
   svint8_t array[2]; /* { dg-error {array elements cannot have SVE
type 'svint8_t'} } */
   svint8_t zero_length_array[0]; /* { dg-error {array elements cannot
have SVE type 'svint8_t'} } */
   svint8_t empty_init_array[] = {}; /* { dg-error {array elements
cannot have SVE type 'svint8_t'} } */
-                                   /* { dg-error {empty scalar
initializer} "" { target *-*-* } .-1 } */
   typedef svint8_t vla_type[n]; /* { dg-error {array elements cannot
have SVE type 'svint8_t'} } */

   /* Assignment.  */
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/sizeless-2.c
b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/sizeless-2.c
index 7174393..9986d27 100644
--- a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/sizeless-2.c
+++ b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/sizeless-2.c
@@ -83,7 +83,6 @@ statements (int n)
   svint8_t array[2]; /* { dg-error {array elements cannot have SVE
type 'svint8_t'} } */
   svint8_t zero_length_array[0]; /* { dg-error {array elements cannot
have SVE type 'svint8_t'} } */
   svint8_t empty_init_array[] = {}; /* { dg-error {array elements
cannot have SVE type 'svint8_t'} } */
-                                   /* { dg-error {empty scalar
initializer} "" { target *-*-* } .-1 } */
   typedef svint8_t vla_type[n]; /* { dg-error {array elements cannot
have SVE type 'svint8_t'} } */

   /* Assignment.  */

>
> --
> Joseph S. Myers
> joseph@codesourcery.com
-------------- next part --------------
diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c
index d8025de..1302486 100644
--- a/gcc/c/c-typeck.c
+++ b/gcc/c/c-typeck.c
@@ -9968,7 +9968,8 @@ process_init_element (location_t loc, struct c_expr value, bool implicit,
   /* Ignore elements of an initializer for a variable-size type.
      Those are diagnosed in digest_init.  */
   if (COMPLETE_TYPE_P (constructor_type)
-      && TREE_CODE (TYPE_SIZE (constructor_type)) != INTEGER_CST)
+      && TREE_CODE (TYPE_SIZE (constructor_type)) != INTEGER_CST
+      && TREE_CODE (TYPE_SIZE (constructor_type)) != POLY_INT_CST)
     return;
 
   if (!implicit && warn_designated_init && !was_designated
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/sizeless-1.c b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/sizeless-1.c
index ec892a3..e53b871 100644
--- a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/sizeless-1.c
+++ b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/sizeless-1.c
@@ -83,7 +83,6 @@ statements (int n)
   svint8_t array[2]; /* { dg-error {array elements cannot have SVE type 'svint8_t'} } */
   svint8_t zero_length_array[0]; /* { dg-error {array elements cannot have SVE type 'svint8_t'} } */
   svint8_t empty_init_array[] = {}; /* { dg-error {array elements cannot have SVE type 'svint8_t'} } */
-  				    /* { dg-error {empty scalar initializer} "" { target *-*-* } .-1 } */
   typedef svint8_t vla_type[n]; /* { dg-error {array elements cannot have SVE type 'svint8_t'} } */
 
   /* Assignment.  */
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/sizeless-2.c b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/sizeless-2.c
index 7174393..9986d27 100644
--- a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/sizeless-2.c
+++ b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/sizeless-2.c
@@ -83,7 +83,6 @@ statements (int n)
   svint8_t array[2]; /* { dg-error {array elements cannot have SVE type 'svint8_t'} } */
   svint8_t zero_length_array[0]; /* { dg-error {array elements cannot have SVE type 'svint8_t'} } */
   svint8_t empty_init_array[] = {}; /* { dg-error {array elements cannot have SVE type 'svint8_t'} } */
-  				    /* { dg-error {empty scalar initializer} "" { target *-*-* } .-1 } */
   typedef svint8_t vla_type[n]; /* { dg-error {array elements cannot have SVE type 'svint8_t'} } */
 
   /* Assignment.  */
-------------- next part --------------
gcc/c/ChangeLog:

2020-03-13  Christophe Lyon  <christophe.lyon@linaro.org>

	* c-typeck.c (process_init_element): Handle constructor_type with
	type size represented by POLY_INT_CST.

gcc/testsuite/ChangeLog:

2020-03-13  Christophe Lyon  <christophe.lyon@linaro.org>

	* gcc.target/aarch64/sve/acle/general-c/sizeless-1.c: Remove
	superfluous dg-error.
	* gcc.target/aarch64/sve/acle/general-c/sizeless-2.c: Likewise.