git: 1062db307002 - main - libcxxrt: allow build with gcc13 and --no-undefined-version

The branch main has been updated by brooks:

URL: https://cgit.FreeBSD.org/src/commit/?id=1062db30700230a26fdc90088a4e2bdb6b6e4d6d

commit 1062db30700230a26fdc90088a4e2bdb6b6e4d6d
Author:     Brooks Davis <brooks@FreeBSD.org>
AuthorDate: 2024-05-17 20:22:22 +0000
Commit:     Brooks Davis <brooks@FreeBSD.org>
CommitDate: 2024-05-17 20:50:57 +0000

    libcxxrt: allow build with gcc13 and --no-undefined-version
    
    GCC 13 supports _Float16 and __int128 on fewer architectures than clang
    and thus libcxxrt compiled with gcc13 is sometimes missing related
    symbols.  Hack around this by explicitly appending --undefined-version
    to LDFLAGS in problematic cases.
    
    Reviewed by:    theraven, dim
    Differential Revision:  https://reviews.freebsd.org/D45233
---
 lib/libcxxrt/Makefile | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/lib/libcxxrt/Makefile b/lib/libcxxrt/Makefile
index 6ad89e9da107..7a683ba779f6 100644
--- a/lib/libcxxrt/Makefile
+++ b/lib/libcxxrt/Makefile
@@ -42,3 +42,13 @@ Version-64.map: Version.map
 .endif
 
 .include <bsd.lib.mk>
+
+# gcc13 doesn't support _Float16 on riscv, powerpc64, and x86 or __int128
+# on i386.  Disable checks for missing symbols to allow this to link.
+#
+# XXX: This is a hack that hides an ABI divergence between clang and gcc.
+.if ${COMPILER_TYPE} == "gcc" && \
+    (${MACHINE_ARCH} == "amd64" || ${MACHINE_ARCH} == "i386" || \
+     ${MACHINE_ARCH:Mpowerpc64*} || ${MACHINE_ARCH} == "riscv64")
+LDFLAGS+=	-Wl,--undefined-version
+.endif