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clang: unknown warning option #1606

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bagder opened this issue Jun 22, 2017 · 4 comments
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clang: unknown warning option #1606

bagder opened this issue Jun 22, 2017 · 4 comments
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@MarcelRaad
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@bagder
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bagder commented Jun 22, 2017

I did this

The Travis CI debug builds on Mac shows a warning that an unknown warning is used:

warning: unknown warning option '-Wcomma' [-Wunknown-warning-option]

Example.

I expected the following

No compiler warnings on unknown options used

curl/libcurl version

current git

operating system

Linux
@bagder bagder added the build label Jun 22, 2017
@MarcelRaad
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MarcelRaad commented Jun 22, 2017 •
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Ah, this is not Linux, this is Mac OS. This Apple clang identifies itself as version 7.3.0, while clang trunk is currently 5.0. Since 7.0, it doesn't give any info about which clang version it's based on anymore.

I'm already looking into that, but as I'm not a Mac user myself, I probably can't maintain a separate Apple clang version list.

Given that every clang was treated as version 4.2.1 until recently, maybe we could just treat every new Apple clang version as the latest version the Apple clang version string contained the actual clang version (3.6 in XCode 6.4)? I guess we don't have access to the operating system used in the m4 scripts easily?

@bagder
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bagder commented Jun 22, 2017

Iterating over the options and try which ones that work is also probably a bit complicated since it doesn't seem to exit or properly signal for unknown warning options, other than that message on stderr and it feels error-prone to grep for that!

I guess we don't have access to the operating system used in the m4 scripts easily?

It's there in the $host variable:

     case $host in
     *-*-darwin*)
        echo "this is mac"
        ;;
     *)
        echo "something else"
        ;;
     esac

@bagder
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bagder commented Jun 22, 2017

maybe we could just treat every new Apple clang version as the latest version the Apple clang version string contained the actual clang version (3.6 in XCode 6.4)?

Yes, I think that's a decent default work-around, then we can add support for the specific mac-clangs we know support newer options. The latest mac compiler does support -Wcomma though!

My dev mac has the latest OS and xcode installed I think:

$ clang --version
Apple LLVM version 8.1.0 (clang-802.0.42)
Target: x86_64-apple-darwin16.6.0

@MarcelRaad MarcelRaad mentioned this issue Jun 22, 2017
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MarcelRaad added a commit to MarcelRaad/curl that referenced this issue Jun 24, 2017
@MarcelRaad
curl-compilers.m4: fix unknown-warning-option on Apple clang
8072cc5 
Since 5598b0b, clang -v is used to
detect the clang version. The version number was expected to come after
the word "version". For Apple clang, this doesn't work as it has its
own versioning scheme.
The version number is now first searched after the string
"based on LLVM". This works for Apple clang before version 7, and also
for e.g. Ubuntu's clang up to version 3.7. If it's not found and the
version string contains "Apple LLVM version", clang version 3.7 is
assumed, which is the version that comes with Xcode 7. Otherwise, the
version number is still expected after the word "version", which works
for very old Apple clang versions.

Ref: https://trac.macports.org/wiki/XcodeVersionInfo
Fixes curl#1606
Closes curl#1607
@bagder
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bagder commented Jun 27, 2017

For future reference, here's a gist with this info: https://gist.github.com/epipping/ef8b02b0cfaec4a5ebf3a57092145a3f by @epipping

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