Re: [PATCH v6 01/19] configure, meson: override C compiler for cmake

[Jag Raman]

> On Feb 18, 2022, at 9:49 AM, Jag Raman <jag.raman@oracle.com> wrote:
> 
> 
> 
>> On Feb 18, 2022, at 7:13 AM, Paolo Bonzini <pbonzini@redhat.com> wrote:
>> 
>> On 2/18/22 04:40, Jag Raman wrote:
>>>> On Feb 17, 2022, at 7:09 AM, Peter Maydell <peter.maydell@linaro.org> 
>>>> wrote:
>>>> 
>>>> On Thu, 17 Feb 2022 at 07:56, Jagannathan Raman <jag.raman@oracle.com> 
>>>> wrote:
>>>>> 
>>>>> The compiler path that cmake gets from meson is corrupted. It results in
>>>>> the following error:
>>>>> | -- The C compiler identification is unknown
>>>>> | CMake Error at CMakeLists.txt:35 (project):
>>>>> | The CMAKE_C_COMPILER:
>>>>> | /opt/rh/devtoolset-9/root/bin/cc;-m64;-mcx16
>>>>> | is not a full path to an existing compiler tool.
>>>>> 
>>>>> Explicitly specify the C compiler for cmake to avoid this error
>>>> 
>>>> This sounds like a bug in Meson. Is there a Meson bug report
>>>> we can reference in the commit message here ?
>>> Hi Peter,
>>> This issue reproduces with the latest meson [1] also.
>> 
>> 0.60.0 or more recent versions should have a fix, which would do exactly 
>> what this patch does: do not define CMAKE_C_COMPILER_LAUNCHER, and place the 
>> whole binaries.c variable in CMAKE_C_COMPILER. What are the contents of the 
>> genrated CMakeMesonToolchainFile.cmake and CMakeCache.txt files, without and 
>> with your patch?
> 
> I’ll checkout what’s going on at my end. But the issue reproduces with
> meson 0.61 from what I can tell:
> # ../configure --target-list=x86_64-softmmu --enable-debug 
> --enable-vfio-user-server;
> The Meson build system
> Version: 0.61.2
> …
> …
> | /opt/rh/devtoolset-9/root/usr/bin/cc;-m64;-mcx16
> 
> | is not a full path to an existing compiler tool.
> 
> 
> Concerning the generated files, I see the following in 
> CMakeMesonToolchainFile.cmake:
> Without patch: set(CMAKE_C_COMPILER "/opt/rh/devtoolset-9/root/usr/bin/cc" 
> "-m64" "-mcx16”)
> With patch: set(CMAKE_C_COMPILER "cc" "-m64" "-mcx16")

I’m not sure if you’re interested in the contents of the whole file. But 
they’re here:

Without patch: https://pastebin.com/sbwtvHy0 (also has error log at the end)
With patch: https://pastebin.com/buRYSp2R

Thank you!
--
Jag

> 
>> 
>>> I noticed the following about the “binaries” section [2]. The manual
>>> says meson could pass the values in this section to find_program [3].
>>> As such I’m wondering if it’s OK to set compiler flags in this section
>>> because find_program doesn’t seem to accept any compiler flags.
>> 
>> The full quote of the manual is "These can be used internally by Meson, or 
>> by the find_program function", and the C compiler variable "c" is in the 
>> former category.
>> 
>> There is an important difference between the flags in "binaries" and those 
>> in "built-in options". What is in "binaries" is used when requesting e.g. 
>> the compiler search path, while what is in "built-in options" is not.  So 
>> options like "-m32" are definitely part of "binaries", not "built-in 
>> options":
>> 
>>   $ gcc --print-multi-os-directory
>>   ../lib64
>>   $ gcc -m32 --print-multi-os-directory
>>   ../lib
> 
> Do you know if the “host_machine” section in cross build
> definition file [1] would be any help here?
> 
> [1]: https://mesonbuild.com/Cross-compilation.html#machine-entries
> 
> --
> Jag
> 
>> 
>> Paolo