cc/gcc: Remove -lstdc++ and -lm from gcc LDFLAGS

In Bryan Hundven's patch 1ad439907 from 2010, the author added -lstdc++
and -lm to the host gcc build's LDFLAGS, because at the time the linker
did not correctly include these libraries causing the build to fail.

In modern builds, this causes a problem for canadian gcc builds where
the host machine is mingw32-w64 Windows.

Within the gcc build there is the liblto_plugin module. On Windows this
must be built as the "liblto_plugin.dll" dynamic library. However,
libtool cannot produce a dynamic library unless every library dependency
is also a dynamic library, and falls back to producing a libstdc++.a
static library. liblto_plugin does not require libstdc++ - it
does not contain any C++ code, and the dependency would usually be
elided by the linker.

Unfortunately, in this case, crosstool-ng will never build a
libstdc++.dll dynamic library - only a libstdc++.a static library.
Therefore, there will never be a dynamic library version of stdc++ for
libtool to load and then discard.

This patch corrects the issue by removing "-lstdc++" from LDFLAGS,
because modern versions of gcc are able to correctly include libstdc++
where necessary. It also remove "-lm" for similar reasons.

Signed-off-by: Joel Holdsworth <jholdsworth@nvidia.com>

1 files changed, 0 insertions, 24 deletions

diff --git a/scripts/build/cc/gcc.sh b/scripts/build/cc/gcc.sh
index 0f369a47..59666160 100644
--- a/scripts/build/cc/gcc.sh
+++ b/scripts/build/cc/gcc.sh
@@ -396,12 +396,6 @@ do_gcc_core_backend() {
             host_libstdcxx_flags+=("-Wl,-Bstatic,-lstdc++")
             host_libstdcxx_flags+=("-lm")
         fi
-        # Companion libraries are build static (eg !shared), so
-        # the libstdc++ is not pulled automatically, although it
-        # is needed. Shoe-horn it in our LDFLAGS
-        # Ditto libm on some Fedora boxen
-        core_LDFLAGS+=("-lstdc++")
-        core_LDFLAGS+=("-lm")
     else
         if [ "${CT_CC_GCC_STATIC_LIBSTDCXX}" = "y" -a "${CT_GCC_older_than_6}" = "y" ]; then
             # this is from CodeSourcery arm-2010q1-202-arm-none-linux-gnueabi.src.tar.bz2
@@ -412,12 +406,6 @@ do_gcc_core_backend() {
             host_libstdcxx_flags+=("-Wl,-Bstatic,-lstdc++,-Bdynamic")
             host_libstdcxx_flags+=("-lm")
         fi
-        # When companion libraries are build static (eg !shared),
-        # the libstdc++ is not pulled automatically, although it
-        # is needed. Shoe-horn it in our LDFLAGS
-        # Ditto libm on some Fedora boxen
-        core_LDFLAGS+=("-lstdc++")
-        core_LDFLAGS+=("-lm")
     fi
 
     extra_config+=("--with-gmp=${complibs}")
@@ -1036,12 +1024,6 @@ do_gcc_backend() {
             host_libstdcxx_flags+=("-Wl,-Bstatic,-lstdc++")
             host_libstdcxx_flags+=("-lm")
         fi
-        # Companion libraries are build static (eg !shared), so
-        # the libstdc++ is not pulled automatically, although it
-        # is needed. Shoe-horn it in our LDFLAGS
-        # Ditto libm on some Fedora boxen
-        final_LDFLAGS+=("-lstdc++")
-        final_LDFLAGS+=("-lm")
     else
         if [ "${CT_CC_GCC_STATIC_LIBSTDCXX}" = "y" -a "${CT_GCC_older_than_6}" = "y" ]; then
             # this is from CodeSourcery arm-2010q1-202-arm-none-linux-gnueabi.src.tar.bz2
@@ -1052,12 +1034,6 @@ do_gcc_backend() {
             host_libstdcxx_flags+=("-Wl,-Bstatic,-lstdc++,-Bdynamic")
             host_libstdcxx_flags+=("-lm")
         fi
-        # When companion libraries are build static (eg !shared),
-        # the libstdc++ is not pulled automatically, although it
-        # is needed. Shoe-horn it in our LDFLAGS
-        # Ditto libm on some Fedora boxen
-        final_LDFLAGS+=("-lstdc++")
-        final_LDFLAGS+=("-lm")
     fi
 
     extra_config+=("--with-gmp=${complibs}")