Re: [PATCH] libstdc++: /dev/null is not accessible on Windows

[Jonathan Wakely <jwakely.gcc@gmail.com>]

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On Mon, 5 Feb 2024, 19:07 Torbjörn SVENSSON, <torbjorn.svensson@foss.st.com>
wrote:

> Ok for trunk and releases/gcc-13?
>

OK, thanks


> ---
>
> When running the DejaGNU testsuite on a toolchain built for native
> Windows, the path /dev/null can't be used to open a stream to void.
> On native Windows, the resource is instead named "nul".
>
> In 17_intro/tag_type_explicit_ctor.cc, the following statement would
> fail to match when the DejaGNU testsuite is running in cygwin with a
> native toolchain.
> // dg-error 53 "explicit" "" { target hosted }
>
> The "target hosted"-check is using cpp to verify if _GLIBCXX_HOSTED is
> defined and discards the output by simply redirecting it to /dev/null.
> In v3_target_compile, it's overridden to "nul" for MinGW targets, but
> the same rule applies when host is cygwin, so replace the condition
> with a check for Windows.
>
> The error in the log would look like this for the "target hosted" check:
> cc1plus.exe: fatal error: opening output file /dev/null: No such file or
> directory
>
> The tag_type_explicit_ctor.cc test fails with this on Windows:
> .../tag_type_explicit_ctor.cc:53: error: converting to 'std::defer_lock_t'
> from initializer list would use explicit constructor 'constexpr
> std::defer_lock_t::defer_lock_t()'
> .../tag_type_explicit_ctor.cc:54: error: converting to
> 'std::try_to_lock_t' from initializer list would use explicit constructor
> 'constexpr std::try_to_lock_t::try_to_lock_t()'
> .../tag_type_explicit_ctor.cc:55: error: converting to
> 'std::try_to_lock_t' from initializer list would use explicit constructor
> 'constexpr std::try_to_lock_t::try_to_lock_t()'
> .../tag_type_explicit_ctor.cc:67: error: converting to 'std::defer_lock_t'
> from initializer list would use explicit constructor 'constexpr
> std::defer_lock_t::defer_lock_t()'
> .../tag_type_explicit_ctor.cc:68: error: converting to
> 'std::try_to_lock_t' from initializer list would use explicit constructor
> 'constexpr std::try_to_lock_t::try_to_lock_t()'
> .../tag_type_explicit_ctor.cc:69: error: converting to 'std::adopt_lock_t'
> from initializer list would use explicit constructor 'constexpr
> std::adopt_lock_t::adopt_lock_t()'
>
> Patch has been verified on Windows and Linux.
>
> gcc/testsuite:
>
>         * testsuite/lib/libstdc++.exp: Use "nul" for Windows,
>           "/dev/null" for other environments.
>
> Signed-off-by: Torbjörn SVENSSON <torbjorn.svensson@foss.st.com>
> ---
>  libstdc++-v3/testsuite/lib/libstdc++.exp | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/libstdc++-v3/testsuite/lib/libstdc++.exp
> b/libstdc++-v3/testsuite/lib/libstdc++.exp
> index 24d1b43f11b..58804ecab26 100644
> --- a/libstdc++-v3/testsuite/lib/libstdc++.exp
> +++ b/libstdc++-v3/testsuite/lib/libstdc++.exp
> @@ -615,11 +615,14 @@ proc v3_target_compile { source dest type options } {
>         }
>      }
>
> -    # Small adjustment for MinGW hosts.
> -    if { $dest == "/dev/null" && [ishost "*-*-mingw*"] } {
> +    # Small adjustment for Windows hosts.
> +    if { $dest == "/dev/null"
> +         && [info exists ::env(OS)] && [string match "Windows*"
> $::env(OS)] } {
>         if { $type == "executable" } {
>             set dest "x.exe"
>         } else {
> +           # Windows uses special file named "nul" as a substitute for
> +           # /dev/null
>             set dest "nul"
>         }
>      }
> --
> 2.25.1
>
>