From e455d4c3cb470216a130ca7b13f68977c2658c88 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Storsj=C3=B6?= <martin@martin.st>
Date: Thu, 4 Sep 2025 15:10:57 +0300
Subject: [PATCH] build-llvm: Add an option --use-linker=

This allows overriding which linker to use.

Currently, building LLVM on Ubuntu 25.10 with these scripts fails,
if LLD is available. This, because the GCC on that distribution
produces object files that LLD (and gold) rejects during linking - see
https://github.com/llvm/llvm-project/issues/156667 for details.

By building with --use-linker=bfd, linking does succeed in that
configuration.

Also pass the same option through from build-all.sh.
---
 build-all.sh  |  4 ++--
 build-llvm.sh | 13 +++++++++----
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/build-all.sh b/build-all.sh
index fd87b67..da476a3 100755
--- a/build-all.sh
+++ b/build-all.sh
@@ -24,7 +24,7 @@ HOST_ARGS=""
 
 while [ $# -gt 0 ]; do
     case "$1" in
-    --enable-asserts|--disable-dylib|--with-clang|--thinlto)
+    --enable-asserts|--disable-dylib|--with-clang|--thinlto|--use-linker=*)
         LLVM_ARGS="$LLVM_ARGS $1"
         ;;
     --host-clang|--host-clang=*)
@@ -120,7 +120,7 @@ while [ $# -gt 0 ]; do
     shift
 done
 if [ -z "$PREFIX" ]; then
-    echo "$0 [--host-clang[=clang]] [--enable-asserts] [--disable-dylib] [--with-clang] [--thinlto] [--full-llvm] [--disable-lldb] [--disable-lldb-mi] [--disable-clang-tools-extra] [--host=triple] [--with-default-win32-winnt=0x601] [--with-default-msvcrt=ucrt] [--enable-cfguard|--disable-cfguard] [--no-runtimes] [--llvm-only] [--no-tools] [--wipe-runtimes] [--clean-runtimes] [--stage1] [--profile[=type]] [--pgo[=profile]] [--full-pgo[=type]] dest [pgo-dest]"
+    echo "$0 [--host-clang[=clang]] [--enable-asserts] [--disable-dylib] [--with-clang] [--use-linker=linker] [--thinlto] [--full-llvm] [--disable-lldb] [--disable-lldb-mi] [--disable-clang-tools-extra] [--host=triple] [--with-default-win32-winnt=0x601] [--with-default-msvcrt=ucrt] [--enable-cfguard|--disable-cfguard] [--no-runtimes] [--llvm-only] [--no-tools] [--wipe-runtimes] [--clean-runtimes] [--stage1] [--profile[=type]] [--pgo[=profile]] [--full-pgo[=type]] dest [pgo-dest]"
     exit 1
 fi
 if [ -n "$PREFIX_PGO" ] && [ -z "$PGO" ] && [ -z "$FULL_PGO" ]; then
diff --git a/build-llvm.sh b/build-llvm.sh
index 1a3e306..e94bb3f 100755
--- a/build-llvm.sh
+++ b/build-llvm.sh
@@ -40,6 +40,9 @@ while [ $# -gt 0 ]; do
         WITH_CLANG=1
         BUILDDIR="$BUILDDIR-withclang"
         ;;
+    --use-linker=*)
+        USE_LINKER="${1#*=}"
+        ;;
     --thinlto)
         LTO="thin"
         BUILDDIR="$BUILDDIR-thinlto"
@@ -104,7 +107,7 @@ done
 BUILDDIR="$BUILDDIR$ASSERTSSUFFIX"
 if [ -z "$CHECKOUT_ONLY" ]; then
     if [ -z "$PREFIX" ]; then
-        echo $0 [--enable-asserts] [--with-clang] [--thinlto] [--lto] [--instrumented[=type]] [--pgo[=profile]] [--disable-dylib] [--full-llvm] [--with-python] [--disable-lldb] [--disable-clang-tools-extra] [--host=triple] [--no-llvm-tool-reuse] [--macos-native-tools] dest
+        echo $0 [--enable-asserts] [--with-clang] [--use-linker=linker] [--thinlto] [--lto] [--instrumented[=type]] [--pgo[=profile]] [--disable-dylib] [--full-llvm] [--with-python] [--disable-lldb] [--disable-clang-tools-extra] [--host=triple] [--no-llvm-tool-reuse] [--macos-native-tools] dest
         exit 1
     fi
 
@@ -190,7 +193,7 @@ if [ -n "$HOST" ]; then
     if [ -n "$WITH_CLANG" ]; then
         CMAKEFLAGS="$CMAKEFLAGS -DCMAKE_C_COMPILER=clang"
         CMAKEFLAGS="$CMAKEFLAGS -DCMAKE_CXX_COMPILER=clang++"
-        CMAKEFLAGS="$CMAKEFLAGS -DLLVM_USE_LINKER=lld"
+        CMAKEFLAGS="$CMAKEFLAGS -DLLVM_USE_LINKER=${USE_LINKER:-lld}"
         CMAKEFLAGS="$CMAKEFLAGS -DCMAKE_ASM_COMPILER_TARGET=$HOST"
         CMAKEFLAGS="$CMAKEFLAGS -DCMAKE_C_COMPILER_TARGET=$HOST"
         CMAKEFLAGS="$CMAKEFLAGS -DCMAKE_CXX_COMPILER_TARGET=$HOST"
@@ -267,12 +270,14 @@ elif [ -n "$WITH_CLANG" ]; then
     # tools.
     CMAKEFLAGS="$CMAKEFLAGS -DCMAKE_C_COMPILER=clang"
     CMAKEFLAGS="$CMAKEFLAGS -DCMAKE_CXX_COMPILER=clang++"
-    CMAKEFLAGS="$CMAKEFLAGS -DLLVM_USE_LINKER=lld"
+    CMAKEFLAGS="$CMAKEFLAGS -DLLVM_USE_LINKER=${USE_LINKER:-lld}"
 else
     # Native compilation with the system default compiler.
 
     # Use a faster linker, if available.
-    if command -v ld.lld >/dev/null; then
+    if [ -n "$USE_LINKER" ]; then
+        CMAKEFLAGS="$CMAKEFLAGS -DLLVM_USE_LINKER=$USE_LINKER"
+    elif command -v ld.lld >/dev/null; then
         CMAKEFLAGS="$CMAKEFLAGS -DLLVM_USE_LINKER=lld"
     elif command -v ld.gold >/dev/null; then
         CMAKEFLAGS="$CMAKEFLAGS -DLLVM_USE_LINKER=gold"