gcc: Drop stdlib++ option patch

The patch to gcc to disable use of libstdc++ when configuring the library
during gcc-runtime is old and there are perhaps better ways to do this now.

If removed, most builds still "work" but incorrect values for things like
atomic ops are found during configure. mips64 and ppc fail with on target
simple tests of g++ in testimage.

Instead we can create a dummy libstdc++ which allows the correct configure
test results to be obtained.

Discussed with upstream about the patch are ongoing, if accepted, we can
switch back to the commandline option if it is added in future.

(From OE-Core rev: 34b0edb0d3120c32063ff7e3dd52be20d60401d5)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

3 files changed, 6 insertions, 121 deletions

diff --git a/meta/recipes-devtools/gcc/gcc-11.2.inc b/meta/recipes-devtools/gcc/gcc-11.2.inc
index f07a5be507..a62f272d3c 100644
--- a/meta/recipes-devtools/gcc/gcc-11.2.inc
+++ b/meta/recipes-devtools/gcc/gcc-11.2.inc
@@ -33,7 +33,6 @@ SRC_URI = "\
            file://0001-gcc-4.3.1-ARCH_FLAGS_FOR_TARGET.patch \
            file://0002-gcc-poison-system-directories.patch \
            file://0004-64-bit-multilib-hack.patch \
-           file://0005-optional-libstdc.patch \
            file://0007-Use-the-defaults.h-in-B-instead-of-S-and-t-oe-in-B.patch \
            file://0009-cpp-honor-sysroot.patch \
            file://0011-Define-GLIBC_DYNAMIC_LINKER-and-UCLIBC_DYNAMIC_LINKE.patch \
diff --git a/meta/recipes-devtools/gcc/gcc-runtime.inc b/meta/recipes-devtools/gcc/gcc-runtime.inc
index 4839a6687a..c39a0caf8a 100644
--- a/meta/recipes-devtools/gcc/gcc-runtime.inc
+++ b/meta/recipes-devtools/gcc/gcc-runtime.inc
@@ -64,7 +64,11 @@ DEBUG_PREFIX_MAP:class-target = " \
    "
 
 do_configure () {
-        export CXX="${CXX} -nostdinc++ -nostdlib++"
+        export CXX="${CXX} -nostdinc++ -L${WORKDIR}/dummylib"
+        # libstdc++ isn't built yet so CXX would error not able to find it which breaks stdc++'s configure
+        # tests. Create a dummy empty lib for the purposes of configure.
+        mkdir -p ${WORKDIR}/dummylib
+        touch ${WORKDIR}/dummylib/libstdc++.so
         for d in libgcc ${RUNTIMETARGET}; do
                 echo "Configuring $d"
                 rm -rf ${B}/${TARGET_SYS}/$d/
@@ -302,7 +306,7 @@ do_check() {
     export DEJAGNU="${WORKDIR}/dejagnu/site.exp"
 
     # HACK: this works around the configure setting CXX with -nostd* args
-    sed -i 's/-nostdinc++ -nostdlib++//g' $(find ${B} -name testsuite_flags | head -1)
+    sed -i 's#-nostdinc++ -L${WORKDIR}/dummylib##g' $(find ${B} -name testsuite_flags | head -1)
 
     if [ "${TOOLCHAIN_TEST_TARGET}" = "user" ]; then
         # qemu user has issues allocating large amounts of memory
diff --git a/meta/recipes-devtools/gcc/gcc/0005-optional-libstdc.patch b/meta/recipes-devtools/gcc/gcc/0005-optional-libstdc.patch
deleted file mode 100644
index b856c5dea3..0000000000
--- a/meta/recipes-devtools/gcc/gcc/0005-optional-libstdc.patch
+++ /dev/null
@@ -1,118 +0,0 @@
-From: Richard Purdie <richard.purdie@linuxfoundation.org>
-Subject: [PATCH 3/5] gcc: Add --nostdlib++ option
-
-[gcc-runtime builds libstdc++ separately from gcc-cross-*. Its configure tests using g++
-will not run correctly since by default the linker will try to link against libstdc++
-which shouldn't exist yet. We need an option to disable -lstdc++
-option whilst leaving -lc, -lgcc and other automatic library dependencies added by gcc
-driver. This patch adds such an option which only disables the -lstdc++.]
-
-[A "standard" gcc build uses xgcc and hence avoids this. We should ask upstream how to
-do this officially, the likely answer is don't build libstdc++ separately.]
-
-OpenEmbedded/Yocto Project builds libgcc and the other gcc runtime libraries
-separately from the compiler and slightly differently to the standard gcc build.
-
-In general this works well but in trying to build them separately we run into
-an issue since we're using our gcc, not xgcc and there is no way to tell configure
-to use libgcc but not look for libstdc++.
-
-This adds such an option allowing such configurations to work.
-
-2021-10-26 Richard Purdie <richard.purdie@linuxfoundation.org>
-
-gcc/c-family/ChangeLog:
-
-    * c.opt: Add --nostdlib++ option
-
-gcc/cp/ChangeLog:
-
-    * g++spec.c (lang_specific_driver): Add --nostdlib++ option
-
-gcc/ChangeLog:
-
-    * doc/invoke.texi: Document --nostdlib++ option
-    * gcc.c: Add --nostdlib++ option
-
-Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
-
-Upstream-Status: Submitted [https://gcc.gnu.org/pipermail/gcc-patches/2021-October/582724.html]
----
- gcc/c-family/c.opt  | 4 ++++
- gcc/cp/g++spec.c    | 1 +
- gcc/doc/invoke.texi | 8 +++++++-
- gcc/gcc.c           | 1 +
- 4 files changed, 13 insertions(+), 1 deletion(-)
-
-Index: gcc-11.2.0/gcc/c-family/c.opt
-===================================================================
---- gcc-11.2.0.orig/gcc/c-family/c.opt
-+++ gcc-11.2.0/gcc/c-family/c.opt
-@@ -2153,6 +2153,10 @@ nostdinc++
- C++ ObjC++
- Do not search standard system include directories for C++.
- 
-+nostdlib++
-+Driver
-+Do not link standard C++ runtime library
-+
- o
- C ObjC C++ ObjC++ Joined Separate
- ; Documented in common.opt
-Index: gcc-11.2.0/gcc/cp/g++spec.c
-===================================================================
---- gcc-11.2.0.orig/gcc/cp/g++spec.c
-+++ gcc-11.2.0/gcc/cp/g++spec.c
-@@ -159,6 +159,7 @@ lang_specific_driver (struct cl_decoded_
-       switch (decoded_options[i].opt_index)
-        {
-        case OPT_nostdlib:
-+       case OPT_nostdlib__:
-        case OPT_nodefaultlibs:
-          library = -1;
-          break;
-Index: gcc-11.2.0/gcc/doc/invoke.texi
-===================================================================
---- gcc-11.2.0.orig/gcc/doc/invoke.texi
-+++ gcc-11.2.0/gcc/doc/invoke.texi
-@@ -239,6 +239,7 @@ in the following sections.
- -fno-weak  -nostdinc++ @gol
- -fvisibility-inlines-hidden @gol
- -fvisibility-ms-compat @gol
-+-nostdlib++ @gol
- -fext-numeric-literals @gol
- -flang-info-include-translate@r{[}=@var{header}@r{]} @gol
- -flang-info-include-translate-not @gol
-@@ -632,7 +633,7 @@ Objective-C and Objective-C++ Dialects}.
- -pie  -pthread  -r  -rdynamic @gol
- -s  -static  -static-pie  -static-libgcc  -static-libstdc++ @gol
- -static-libasan  -static-libtsan  -static-liblsan  -static-libubsan @gol
---shared  -shared-libgcc  -symbolic @gol
-+-shared  -shared-libgcc  -symbolic -nostdlib++ @gol
- -T @var{script}  -Wl,@var{option}  -Xlinker @var{option} @gol
- -u @var{symbol}  -z @var{keyword}}
- 
-@@ -15721,6 +15722,11 @@ Specify that the program entry point is
- interpreted by the linker; the GNU linker accepts either a symbol name
- or an address.
- 
-+@item -nostdlib++
-+@opindex nostdlib++
-+Do not use the standard system C++ runtime libraries when linking.
-+Only the libraries you specify will be passed to the linker.
-+
- @item -pie
- @opindex pie
- Produce a dynamically linked position independent executable on targets
-Index: gcc-11.2.0/gcc/gcc.c
-===================================================================
---- gcc-11.2.0.orig/gcc/gcc.c
-+++ gcc-11.2.0/gcc/gcc.c
-@@ -1162,6 +1162,7 @@ proper position among the other output f
-     %(mflib) " STACK_SPLIT_SPEC "\
-     %{fprofile-arcs|fprofile-generate*|coverage:-lgcov} " SANITIZER_SPEC " \
-     %{!nostdlib:%{!r:%{!nodefaultlibs:%(link_ssp) %(link_gcc_c_sequence)}}}\
-+    %{!nostdlib++:}\
-     %{!nostdlib:%{!r:%{!nostartfiles:%E}}} %{T*}  \n%(post_link) }}}}}}"
- #endif
-