[RFC,v1,3/4] Add testing cases for flexible array members in unions and alone in structures.
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Commit Message
gcc/testsuite/ChangeLog:
* gcc.dg/flex-array-in-union-1.c: New test.
* gcc.dg/flex-array-in-union-2.c: New test.
---
gcc/testsuite/gcc.dg/flex-array-in-union-1.c | 37 +++++++++++++++++
gcc/testsuite/gcc.dg/flex-array-in-union-2.c | 42 ++++++++++++++++++++
2 files changed, 79 insertions(+)
create mode 100644 gcc/testsuite/gcc.dg/flex-array-in-union-1.c
create mode 100644 gcc/testsuite/gcc.dg/flex-array-in-union-2.c
Comments
On Fri, 19 Apr 2024, Qing Zhao wrote:
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/flex-array-in-union-1.c: New test.
> * gcc.dg/flex-array-in-union-2.c: New test.
There should also be a -pedantic-errors test that these constructs get
errors with -pedantic-errors.
The tests mix two cases: flexible arrays in unions, and flexible arrays on
their own in structures. That means the test names are misleading; either
they should be renamed, or the struct tests should be split out.
Note that "no named members" also includes the case where there are
unnamed bit-fields together with a flexible array member, so that should
be tested as well.
Since this patch series involves changes for both C and C++, it would be
best for the tests to be c-c++-common tests. But if that's problematic
for some reason - if there's still too much difference in behavior between
C and C++ - then there should at least be tests for C++ that are as
similar as possible to the tests for C.
> On Apr 23, 2024, at 14:53, Joseph Myers <josmyers@redhat.com> wrote:
>
> On Fri, 19 Apr 2024, Qing Zhao wrote:
>
>> gcc/testsuite/ChangeLog:
>>
>> * gcc.dg/flex-array-in-union-1.c: New test.
>> * gcc.dg/flex-array-in-union-2.c: New test.
>
> There should also be a -pedantic-errors test that these constructs get
> errors with -pedantic-errors.
Okay, will add.
>
> The tests mix two cases: flexible arrays in unions, and flexible arrays on
> their own in structures. That means the test names are misleading; either
> they should be renamed, or the struct tests should be split out.
Okay, will update this.
>
> Note that "no named members" also includes the case where there are
> unnamed bit-fields together with a flexible array member, so that should
> be tested as well.
Will add such testing cases.
>
> Since this patch series involves changes for both C and C++, it would be
> best for the tests to be c-c++-common tests. But if that's problematic
> for some reason - if there's still too much difference in behavior between
> C and C++ - then there should at least be tests for C++ that are as
> similar as possible to the tests for C.
I tried to put these two testing cases to c-c++-common, there were some inconsistent behavior
I cannot resolve at that time, I will try to fix those issue or add C++ testing cases.
Thanks for the review.
Qing
>
> --
> Joseph S. Myers
> josmyers@redhat.com
>
new file mode 100644
@@ -0,0 +1,37 @@
+/* testing the correct usage of flexible array members in unions
+ and alone in structure. */
+/* { dg-do run} */
+/* { dg-options "-O2 -Wpedantic" } */
+
+union with_fam_1 {
+ int a;
+ int b[]; /* { dg-warning "flexible array member in union is a GCC extension" } */
+};
+
+union with_fam_2 {
+ char a;
+ int b[]; /* { dg-warning "flexible array member in union is a GCC extension" } */
+};
+
+union with_fam_3 {
+ char a[]; /* { dg-warning " flexible array member in union is a GCC extension" } */
+ int b[]; /* { dg-warning "flexible array member in union is a GCC extension" } */
+};
+
+struct only_fam {
+ int b[]; /* { dg-warning "flexible array member in a struct with no named members is a GCC extension" } */
+};
+
+int main ()
+{
+ if (sizeof (union with_fam_1) != sizeof (int))
+ __builtin_abort ();
+ if (sizeof (union with_fam_2) != __alignof__ (int))
+ __builtin_abort ();
+ if (sizeof (union with_fam_3) != 0)
+ __builtin_abort ();
+ if (sizeof (struct only_fam) != 0)
+ __builtin_abort ();
+ return 0;
+}
+
new file mode 100644
@@ -0,0 +1,42 @@
+/* testing the correct usage of flexible array members in unions
+ and alone in structure: initialization */
+/* { dg-do run} */
+/* { dg-options "-O2" } */
+
+union with_fam_1 {
+ int a;
+ int b[];
+} with_fam_1_v = {.b = {1, 2, 3, 4}};
+
+union with_fam_2 {
+ int a;
+ char b[];
+} with_fam_2_v = {.a = 0x1f2f3f4f};
+
+union with_fam_3 {
+ char a[];
+ int b[];
+} with_fam_3_v = {.b = {0x1f2f3f4f, 0x5f6f7f7f}};
+
+struct only_fam {
+ int b[];
+} only_fam_v = {{7, 11}};
+
+int main ()
+{
+ if (with_fam_1_v.b[3] != 4
+ || with_fam_1_v.b[0] != 1)
+ __builtin_abort ();
+ if (with_fam_2_v.b[3] != 0x1f
+ || with_fam_2_v.b[0] != 0x4f)
+ __builtin_abort ();
+ if (with_fam_3_v.a[0] != 0x4f
+ || with_fam_3_v.a[7] != 0x5f)
+ __builtin_abort ();
+ if (only_fam_v.b[0] != 7
+ || only_fam_v.b[1] != 11)
+ __builtin_abort ();
+
+ return 0;
+}
+