[flang-commits] [flang] dea50a1 - [flang][Driver] Enable FLANG_DEFAULT_LINKER (#149786)

[via flang-commits]

Author: parabola94
Date: 2025-08-10T05:21:14+09:00
New Revision: dea50a1797c9cb70ce86284c25cc9277f3d88fc8

URL: https://github.com/llvm/llvm-project/commit/dea50a1797c9cb70ce86284c25cc9277f3d88fc8
DIFF: https://github.com/llvm/llvm-project/commit/dea50a1797c9cb70ce86284c25cc9277f3d88fc8.diff

LOG: [flang][Driver] Enable FLANG_DEFAULT_LINKER (#149786)

The default linker can be changed by a CMake variable
CLANG_DEFAULT_LINKER. However, it also changes the default linker
invoked by clang. In fact, there already exists FLANG_DEFAULT_LINKER,
but it does not work. This patch fixes it.

Note that FLANG_DEFAULT_LINKER will have the same value as
CLANG_DEFAULT_LINKER unless it is defined explicitly. That means this
patch does not affect the current behavior.

Fixes #73153

---------

Co-authored-by: Michael Kruse <github at meinersbur.de>

Added: 
    

Modified: 
    flang/CMakeLists.txt
    flang/include/flang/Config/config.h.cmake
    flang/test/Driver/linker-flags.f90
    flang/tools/flang-driver/driver.cpp

Removed: 
    


################################################################################
diff  --git a/flang/CMakeLists.txt b/flang/CMakeLists.txt
index 0bfada476348a..1d16c33f44900 100644
--- a/flang/CMakeLists.txt
+++ b/flang/CMakeLists.txt
@@ -317,7 +317,7 @@ if (NOT ENABLE_LINKER_BUILD_ID)
   set(ENABLE_LINKER_BUILD_ID OFF CACHE BOOL "pass --build-id to ld")
 endif()
 
-set(FLANG_DEFAULT_LINKER "" CACHE STRING
+set(FLANG_DEFAULT_LINKER "${CLANG_DEFAULT_LINKER}" CACHE STRING
   "Default linker to use (linker name or absolute path, empty for platform default)")
 
 set(FLANG_DEFAULT_RTLIB "" CACHE STRING

diff  --git a/flang/include/flang/Config/config.h.cmake b/flang/include/flang/Config/config.h.cmake
index fd34d3f403631..92fbd14c3d6db 100644
--- a/flang/include/flang/Config/config.h.cmake
+++ b/flang/include/flang/Config/config.h.cmake
@@ -1,10 +1,10 @@
-#===-- include/flang/Config/config.h.cmake ---------------------------------===#
-#
-# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-# See https://llvm.org/LICENSE.txt for license information.
-# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-#
-#===------------------------------------------------------------------------===#
+//===-- include/flang/Config/config.h.cmake -------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
 
 /* This generated file is for internal use. Do not include it from headers. */
 
@@ -16,6 +16,8 @@
 
 #define FLANG_VERSION            "${FLANG_VERSION}"
 
+#define FLANG_DEFAULT_LINKER     "${FLANG_DEFAULT_LINKER}"
+
 #endif
 
 

diff  --git a/flang/test/Driver/linker-flags.f90 b/flang/test/Driver/linker-flags.f90
index ad48ea1b9e9b1..2b56fdfb8da05 100644
--- a/flang/test/Driver/linker-flags.f90
+++ b/flang/test/Driver/linker-flags.f90
@@ -77,7 +77,7 @@
 ! MINGW-SAME: -lflang_rt.runtime
 ! MINGW-STATIC-FLANGRT: "{{.*}}{{\\|/}}libflang_rt.runtime.a"
 
-! NOTE: This also matches lld-link (when CLANG_DEFAULT_LINKER=lld) and
+! NOTE: This also matches lld-link (when FLANG_DEFAULT_LINKER=lld) and
 !       any .exe suffix that is added when resolving to the full path of
 !       (lld-)link.exe on Windows platforms. The suffix may not be added
 !       when the executable is not found or on non-Windows platforms.

diff  --git a/flang/tools/flang-driver/driver.cpp b/flang/tools/flang-driver/driver.cpp
index 8321b165ba5bb..bd878b7a642f1 100644
--- a/flang/tools/flang-driver/driver.cpp
+++ b/flang/tools/flang-driver/driver.cpp
@@ -16,6 +16,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "clang/Driver/Driver.h"
+#include "flang/Config/config.h"
 #include "flang/Frontend/CompilerInvocation.h"
 #include "flang/Frontend/TextDiagnosticPrinter.h"
 #include "clang/Basic/Diagnostic.h"
@@ -137,6 +138,7 @@ int main(int argc, const char **argv) {
                                   llvm::sys::getDefaultTargetTriple(), diags,
                                   "flang LLVM compiler");
   theDriver.setTargetAndMode(targetandMode);
+  theDriver.setPreferredLinker(FLANG_DEFAULT_LINKER);
 #ifdef FLANG_RUNTIME_F128_MATH_LIB
   theDriver.setFlangF128MathLibrary(FLANG_RUNTIME_F128_MATH_LIB);
 #endif