[cfe-dev] configure doesn't honor CPPFLAGS

James K. Lowden jklowden at schemamania.org
Thu Apr 26 05:45:17 PDT 2012

On Thu, 26 Apr 2012 11:47:14 +0400
Konstantin Tokarev <annulen at yandex.ru> wrote:

> > My experiment building clang with gcc 4.6 on NetBSD today exposed a
> > problem in the clang build system: although I defined CPPFLAGS
> > before invoking configure, the variable wasn't used in the build. 
> Shouldn't you use CXXFLAGS instead?

Not according to the autoconf documentation.  The AC_LANG macro for
example says:

          Do compilation tests using `CXX' and `CXXCPP' and use
          extension `.C' for test programs.  Use compilation flags:
          `CPPFLAGS' with `CXXCPP', and both `CPPFLAGS' and `CXXFLAGS'
          with `CXX'.

Under "Preset Output Variables" it says:

 -- Variable: CPPFLAGS
     Preprocessor options for the C, C++, Objective C, and Objective C++
     preprocessors and compilers.  If it is not set in the environment
     when `configure' runs, the default value is empty.  `configure'
     uses this variable when preprocessing or compiling programs to
     test for C, C++, Objective C, and Objective C++ features.

Is CXXFLAGS supported?  It's not mentioned on the Getting Started page


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