boost: no quotes around compiler (os.environ["CXX"])

[madebr]

Specify library name and version: boost/all

Fixes #2996

• I've read the guidelines for contributing.
• I've followed the PEP8 style guides for Python code in the recipes.
• I've used the latest Conan client version.
• I've tried at least one configuration locally with the
  conan-center hook activated.

[conan-center-bot]

All green in build 1 (a65e512bdec5e486cfddc7c22279e81e5c24b7e7)! 😊

• boost/1.69.0: Generated 131 packages. All logs here
• boost/1.70.0: Generated 131 packages. All logs here
• boost/1.71.0: Generated 131 packages. All logs here
• boost/1.72.0: Generated 131 packages. All logs here
• boost/1.73.0: Generated 131 packages. All logs here
• boost/1.74.0: Generated 131 packages. All logs here

[SSE4]

does it work with compiler wrappers (e.g. ccache, distcc)?

[madebr]

does it work with compiler wrappers (e.g. ccache, distcc)?

No, it didn't.
Removing the quotes obviates the need for shlex.split.
I tested this by setting CXX=ccache /usr/bin/g++ -fchar8_t -fpermissive in my profile.
(just added some random arguments to the compiler)

[SSE4]

okay, this might be tricky to get it working for all cases. I remember, for windows, quotes were needed, e.g. if CC points to the path with spaces, like C:\Program Files\LLVM\bin\clang-cl.exe.
that might be a situation fixing one thing, but breaking another, so please check it carefully.

[SSE4]

/cc @grafikrobot , he may provide his insight on when quotes might (or might not) be needed.

[jgsogo]

I see one potential problem: what if the path to CXX contains blanks?

[madebr]

okay, this might be tricky to get it working for all cases. I remember, for windows, quotes were needed, e.g. if CC points to the path with spaces, like C:\Program Files\LLVM\bin\clang-cl.exe.
that might be a situation fixing one thing, but breaking another, so please check it carefully.

When not using quotes, there is no way to distinguish between a space in a path and spaces for arguments.
When there is a space in the compiler path, should the CXX environment variable contain double quotes?
Or is #2996 invalid and should CXX not contain any arguments and should they be put in CXXFLAGS/CPPFLAGS?

I've tested with the following (on Linux):

mkdir -p "/tmp/best compiler ever/compiler"
ln -s /usr/bin/g++ "/tmp/best compiler ever/compiler"

and putting CXX=ccache "/tmp/best compiler ever/compiler" -fchar8_t -fpermissive in my profile.

Building boost succeeds, but boost's test_package fails because cmake fails to recognize the compiler.

Setting CXX=""/tmp/best compiler ever/compiler" in the profile works btw.

[SSE4]

CXX usually works for multiple arguments, e.g. things like CXX=ccache g++ and CXX=g++ -m32 work out of the box, and it's pretty common use-case.
for instance, on Mac, you always can escape spaces with slashes and don't use quotes: CXX=/Library/Application\ Support/Android/ndk/bin/clang++ will work.
on other hand, on Windows, it's tricky, because there are different things involved:

1. command line passed to the shell (cmd.exe/bash) or function like ShellExecute. in that case shell-specific things like quotes work.
2. command line directly passed to the CreateProcess/exec function. this cannot handle shell-specific things, e.g. quotes, output redirection syntax, background syntax. probably, cmake works this way and doesn't like quotes in command line.

from the conan point of view, we don't know what's going to be done with CXX in the particular build system. puzzling...

[conan-center-bot]

All green in build 2 (e1c4084de20ef6fbacbadb85d130f0d0367364f4)! 😊

• boost/1.69.0: Generated 131 packages. All logs here
• boost/1.70.0: Generated 131 packages. All logs here
• boost/1.71.0: Generated 131 packages. All logs here
• boost/1.72.0: Generated 131 packages. All logs here
• boost/1.73.0: Generated 131 packages. All logs here
• boost/1.74.0: Generated 131 packages. All logs here

[ghost]

I detected other pull requests that are modifying boost/all recipe:

• [boost] Add 'algorithm' lib #3961 #3963
• Boost/1.72.0/mpi #3959
• boost: patch serialization sources #3918
• Boost: Change assertions to warnings #3900
• [boost] Add nowide lib #3894
• boost: add boost/1.75.0 #3872
• Add --disable-icu flag for iconv backend #3855
• Fix boost syntax warning #3522
• Link boost coroutine_exe against CONAN_LIBS #3205
• boost: Correct --disable-iconv option #2657
• Boost components #1925
• boost: fix i18n_backend=icu support for version 1.7{1,2,3}.0 #1704

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[stale]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.