On 9/10/26 11:14 AM, Alex Bennée wrote:
From: Daniel P. Berrangé <[email protected]>

When it finds a cross compiler, tests/tcg/meson.build tries
building test_cc.c to validate that the compiler works. This
includes "stdint.h" as a witness for working C library, however,
that is not a good choice as it can be provided by the toolchain
alone:

   $ rpm -ql gcc-s390x-linux-gnu  | grep /stdint.h
   /usr/lib/gcc/s390x-linux-gnu/16/include/stdint.h

As a result, if you install the s390x GCC cross compiler, but
not any C library, meson decides to use the host compiler instead
of the container:

     cc for aarch64-softmmu          : aarch64-linux-gnu-gcc (from 
'debian-all-test-cross' container)
     cc for loongarch64-softmmu      : loongarch64-unknown-linux-gnu-gcc (from 
'debian-loongarch-cross' container)
     cc for riscv64-softmmu          : riscv64-linux-gnu-gcc (from 
'debian-all-test-cross' container)
     cc for s390x-softmmu            : s390x-linux-gnu-gcc
     cc for x86_64-softmmu           : x86_64-linux-gnu-gcc (from 
'debian-amd64-cross' container)

Eventually this results in failure to run 'make check':

[33/40] Generating tests/tcg/s390x-softmmu-hello with a custom command
FAILED: [code=1] tests/tcg/s390x-softmmu-hello.test
/usr/bin/s390x-linux-gnu-gcc 
/home/berrange/src/virt/qemu/tests/tcg/multiarch/system/hello.c -o 
tests/tcg/s390x-softmmu-hello.test -static -MMD -MF 
tests/tcg/s390x-softmmu-hello.d -Wall -Werror -O0 -g -fno-strict-aliasing 
-nostdlib -ffreestanding -Wa,--noexecstack -I 
/home/berrange/src/virt/qemu/tests/tcg/s390x/system/../../minilib 
/home/berrange/src/virt/qemu/tests/tcg/s390x/system/../../minilib/printf.c -I 
/home/berrange/src/virt/qemu/include/hw/s390x/ipl -march=z13 
../tests/tcg/s390x/system/../head64.S ../tests/tcg/s390x/system/../console.c
In file included from ../tests/tcg/s390x/system/../console.c:8:
../tests/tcg/s390x/system/../../../../pc-bios/s390-ccw/sclp.c:11:10: fatal 
error: string.h: No such file or directory
    11 | #include <string.h>
       |          ^~~~~~~~~~
compilation terminated.

Adding more include files to the test program ensures the
meson probe makes a better decision.

Fixes: e5d084d622b1 (tests/tcg/meson.build: check host cross cc is working)
Signed-off-by: Daniel P. Berrangé <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Alex Bennée <[email protected]>
---
  tests/tcg/test_cc.c | 6 +++++-
  1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tests/tcg/test_cc.c b/tests/tcg/test_cc.c
index d3614a01fe6..fafee055b40 100644
--- a/tests/tcg/test_cc.c
+++ b/tests/tcg/test_cc.c
@@ -1,7 +1,11 @@
  /* SPDX-License-Identifier: GPL-2.0-or-later */
-/* Include a standard header to make sure cross compiler provides them */
+/* Use some standard headers to ensure the cross compiler provides them */
  #include <stdint.h>
+#include <string.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdio.h>
int main(void)
  {

Ideally, we should do separate tests for system vs user tests.
System ones are always compiled with -ffreestanding, while user ones should provide a C library.

From this standard:

https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2023/p2338r3.html
```
A freestanding C implementation is required to provide the entirety of the following headers:

<float.h>
<iso646.h>
<limits.h>
<stdalign.h>
<stdarg.h>
<stdbool.h>
<stddef.h>
<stdint.h>
<stdnoreturn.h>
Most of <string.h> is required (strdup, strndup, strcoll, strxfrm, and strerror are excluded). This includes strtok, which requires global data.
```

Maybe for now we can just remove stdio.h from current patch, as it's not supposed to be provided in a freestanding environment.

Reviewed-by: Pierrick Bouvier <[email protected]>

Regards,
Pierrick

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