Re: PATCH RFA: Add --enable-build-with-cxx to gcc subdirectory

["Joseph S. Myers" <joseph at codesourcery dot com>]

On Sun, 21 Jun 2009, Ian Lance Taylor wrote:

> +ifneq ($(ENABLE_BUILD_WITH_CXX),yes)
>  COMPILER = $(CC)
>  COMPILER_FLAGS = $(CFLAGS)
>  LINKER = $(CC)
>  LINKER_FLAGS = $(CFLAGS)
> +else
> +COMPILER = $(CXX)
> +COMPILER_FLAGS = $(filter-out -fkeep-inline-functions,$(CXXFLAGS))
> +LINKER = $(CXX)
> +LINKER_FLAGS = $(filter-out -fkeep-inline-functions,$(CXXFLAGS))
> +endif

LINKER should only be $(CXX) if --with-host-libstdcxx is not given; for a 
C++ build --with-host-libstdcxx is still useful for a non-bootstrapped 
build to control how the host libstdc++ is linked in.

>  # This is the variable to use when using $(LINKER).
> +ifneq ($(ENABLE_BUILD_WITH_CXX),yes)
>  ALL_LINKERFLAGS = $(ALL_CFLAGS)
> +else
> +ALL_LINKERFLAGS = --static-libstdc++ $(ALL_CXXFLAGS)
> +endif

I'd expect this to break if the host compiler does not support this 
option, and so to need configure checks.  And if --with-host-libstdcxx is 
used that should override the use of this option.

Will this link with static libgcc as well as static libstdc++ or is the 
-static-libgcc option needed for that?  Shared libgcc has the same issues 
as shared libstdc++ with a 4.5 compiler potentially generating calls to 
functions not in an older system shared library, although to a lesser 
extent than libstdc++; I'd say the default should be linking the compiler 
with static libgcc, just as C programs are linked with static libgcc by 
default.

-- 
Joseph S. Myers
joseph@codesourcery.com