[clang] [compiler-rt] Revert "[clang][Darwin] Prefer the toolchain-provided libc++.dylib if there is one" (PR #170912)
Kewen Meng via llvm-commits
llvm-commits at lists.llvm.org
Fri Dec 5 12:03:31 PST 2025
https://github.com/Kewen12 created https://github.com/llvm/llvm-project/pull/170912
Reverts llvm/llvm-project#170303
This PR breaks bots: https://lab.llvm.org/buildbot/#/builders/10/builds/18578. Revert to unblock.
>From 12a532cc430c3b89483ce9cc89bbfc7bea8541e5 Mon Sep 17 00:00:00 2001
From: Kewen Meng <Kewen.Meng at amd.com>
Date: Fri, 5 Dec 2025 12:01:47 -0800
Subject: [PATCH] =?UTF-8?q?Revert=20"[clang][Darwin]=20Prefer=20the=20tool?=
=?UTF-8?q?chain-provided=20libc++.dylib=20if=20there=20i=E2=80=A6"?=
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This reverts commit 190b8d0b4f19e1c3d68c5d153ec7be71a9969192.
---
clang/lib/Driver/ToolChains/Darwin.cpp | 44 +---------
.../usr/lib/libc++.dylib | 0
.../usr/lib/libc++experimental.a | 0
.../usr/bin/.keep | 0
.../usr/include/c++/v1/.keep | 0
.../usr/lib/libc++.a | 0
.../usr/lib/libc++experimental.a | 0
.../Driver/darwin-header-search-libcxx.cpp | 4 +-
clang/test/Driver/darwin-link-libcxx.cpp | 81 -------------------
.../test/Driver/experimental-library-flag.cpp | 8 +-
compiler-rt/cmake/config-ix.cmake | 15 ----
11 files changed, 8 insertions(+), 144 deletions(-)
delete mode 100644 clang/test/Driver/Inputs/basic_darwin_toolchain/usr/lib/libc++.dylib
delete mode 100644 clang/test/Driver/Inputs/basic_darwin_toolchain/usr/lib/libc++experimental.a
delete mode 100644 clang/test/Driver/Inputs/basic_darwin_toolchain_static/usr/bin/.keep
delete mode 100644 clang/test/Driver/Inputs/basic_darwin_toolchain_static/usr/include/c++/v1/.keep
delete mode 100644 clang/test/Driver/Inputs/basic_darwin_toolchain_static/usr/lib/libc++.a
delete mode 100644 clang/test/Driver/Inputs/basic_darwin_toolchain_static/usr/lib/libc++experimental.a
delete mode 100644 clang/test/Driver/darwin-link-libcxx.cpp
diff --git a/clang/lib/Driver/ToolChains/Darwin.cpp b/clang/lib/Driver/ToolChains/Darwin.cpp
index 30c53389dc22f..fc3cd9030f71d 100644
--- a/clang/lib/Driver/ToolChains/Darwin.cpp
+++ b/clang/lib/Driver/ToolChains/Darwin.cpp
@@ -2846,49 +2846,11 @@ void AppleMachO::AddCXXStdlibLibArgs(const ArgList &Args,
CXXStdlibType Type = GetCXXStdlibType(Args);
switch (Type) {
- case ToolChain::CST_Libcxx: {
- // On Darwin, we prioritize a libc++ located in the toolchain to a libc++
- // located in the sysroot. Unlike the driver for most other platforms, on
- // Darwin we do that by explicitly passing the library path to the linker
- // to avoid having to add the toolchain's `lib/` directory to the linker
- // search path, which would make other libraries findable as well.
- //
- // Prefering the toolchain library over the sysroot library matches the
- // behavior we have for headers, where we prefer headers in the toolchain
- // over headers in the sysroot if there are any. Note that it's important
- // for the header search path behavior to match the link-time search path
- // behavior to ensure that we link the program against a library that
- // matches the headers that were used to compile it.
- //
- // Otherwise, we end up compiling against some set of headers and then
- // linking against a different library (which, confusingly, shares the same
- // name) which may have been configured with different options, be at a
- // different version, etc.
- SmallString<128> InstallLib = llvm::sys::path::parent_path(getDriver().Dir);
- llvm::sys::path::append(InstallLib, "lib"); // <install>/lib
- auto Link = [&](StringRef Library) {
- SmallString<128> Shared(InstallLib);
- llvm::sys::path::append(Shared,
- SmallString<4>("lib") + Library + ".dylib");
- SmallString<128> Static(InstallLib);
- llvm::sys::path::append(Static, SmallString<4>("lib") + Library + ".a");
- SmallString<32> Relative("-l");
- Relative += Library;
-
- if (getVFS().exists(Shared)) {
- CmdArgs.push_back(Args.MakeArgString(Shared));
- } else if (getVFS().exists(Static)) {
- CmdArgs.push_back(Args.MakeArgString(Static));
- } else {
- CmdArgs.push_back(Args.MakeArgString(Relative));
- }
- };
-
- Link("c++");
+ case ToolChain::CST_Libcxx:
+ CmdArgs.push_back("-lc++");
if (Args.hasArg(options::OPT_fexperimental_library))
- Link("c++experimental");
+ CmdArgs.push_back("-lc++experimental");
break;
- }
case ToolChain::CST_Libstdcxx:
// Unfortunately, -lstdc++ doesn't always exist in the standard search path;
diff --git a/clang/test/Driver/Inputs/basic_darwin_toolchain/usr/lib/libc++.dylib b/clang/test/Driver/Inputs/basic_darwin_toolchain/usr/lib/libc++.dylib
deleted file mode 100644
index e69de29bb2d1d..0000000000000
diff --git a/clang/test/Driver/Inputs/basic_darwin_toolchain/usr/lib/libc++experimental.a b/clang/test/Driver/Inputs/basic_darwin_toolchain/usr/lib/libc++experimental.a
deleted file mode 100644
index e69de29bb2d1d..0000000000000
diff --git a/clang/test/Driver/Inputs/basic_darwin_toolchain_static/usr/bin/.keep b/clang/test/Driver/Inputs/basic_darwin_toolchain_static/usr/bin/.keep
deleted file mode 100644
index e69de29bb2d1d..0000000000000
diff --git a/clang/test/Driver/Inputs/basic_darwin_toolchain_static/usr/include/c++/v1/.keep b/clang/test/Driver/Inputs/basic_darwin_toolchain_static/usr/include/c++/v1/.keep
deleted file mode 100644
index e69de29bb2d1d..0000000000000
diff --git a/clang/test/Driver/Inputs/basic_darwin_toolchain_static/usr/lib/libc++.a b/clang/test/Driver/Inputs/basic_darwin_toolchain_static/usr/lib/libc++.a
deleted file mode 100644
index e69de29bb2d1d..0000000000000
diff --git a/clang/test/Driver/Inputs/basic_darwin_toolchain_static/usr/lib/libc++experimental.a b/clang/test/Driver/Inputs/basic_darwin_toolchain_static/usr/lib/libc++experimental.a
deleted file mode 100644
index e69de29bb2d1d..0000000000000
diff --git a/clang/test/Driver/darwin-header-search-libcxx.cpp b/clang/test/Driver/darwin-header-search-libcxx.cpp
index e8985a4e22b2f..cc8ec9ceb89b3 100644
--- a/clang/test/Driver/darwin-header-search-libcxx.cpp
+++ b/clang/test/Driver/darwin-header-search-libcxx.cpp
@@ -92,7 +92,7 @@
// CHECK-LIBCXX-SYSROOT_AND_TOOLCHAIN-1: "-internal-isystem" "[[TOOLCHAIN]]/usr/bin/../include/c++/v1"
// CHECK-LIBCXX-SYSROOT_AND_TOOLCHAIN-1-NOT: "-internal-isystem" "[[SYSROOT]]/usr/include/c++/v1"
-// Make sure that using -nostdinc, -nostdinc++ or -nostdlibinc will drop both the toolchain
+// Make sure that using -nostdinc, -nostdinc++ or -nostdlib will drop both the toolchain
// C++ include path and the sysroot one.
//
// RUN: %clang -### %s -fsyntax-only 2>&1 \
@@ -116,7 +116,7 @@
// RUN: -isysroot %S/Inputs/basic_darwin_sdk_usr_cxx_v1 \
// RUN: -stdlib=platform \
// RUN: -nostdinc++ \
-// RUN: | FileCheck -DSYSROOT=%S/Inputs/basic_darwin_sdk_usr_cxx_v1 \
+// RUN: | FileCheck -DSYSROOT=%S/Inputs/basic_darwin_sdk_usr \
// RUN: -DTOOLCHAIN=%S/Inputs/basic_darwin_toolchain \
// RUN: --check-prefix=CHECK-LIBCXX-NOSTDINCXX %s
// CHECK-LIBCXX-NOSTDINCXX: "-cc1"
diff --git a/clang/test/Driver/darwin-link-libcxx.cpp b/clang/test/Driver/darwin-link-libcxx.cpp
deleted file mode 100644
index 1c4f31b257512..0000000000000
--- a/clang/test/Driver/darwin-link-libcxx.cpp
+++ /dev/null
@@ -1,81 +0,0 @@
-// UNSUPPORTED: system-windows
-
-// Tests to check that we link against the toolchain-provided libc++ built library when it is provided.
-// This is required to prefer the toolchain's libc++ over the system's libc++, which matches the behavior
-// we have for header search paths.
-
-// When libc++.dylib is NOT in the toolchain, we should use -lc++ and fall back to the libc++
-// in the sysroot.
-//
-// (1) Without -fexperimental-library.
-// RUN: %clangxx -### %s 2>&1 \
-// RUN: --target=x86_64-apple-darwin \
-// RUN: -ccc-install-dir %S/Inputs/basic_darwin_toolchain_no_libcxx/usr/bin \
-// RUN: | FileCheck -DTOOLCHAIN=%S/Inputs/basic_darwin_toolchain_no_libcxx \
-// RUN: --check-prefix=CHECK-1 %s
-// CHECK-1: "/usr/bin/ld"
-// CHECK-1: "-lc++"
-// CHECK-1-NOT: "[[TOOLCHAIN]]/usr/lib"
-//
-// (2) With -fexperimental-library.
-// RUN: %clangxx -### %s 2>&1 \
-// RUN: --target=x86_64-apple-darwin \
-// RUN: -ccc-install-dir %S/Inputs/basic_darwin_toolchain_no_libcxx/usr/bin \
-// RUN: -fexperimental-library \
-// RUN: | FileCheck -DTOOLCHAIN=%S/Inputs/basic_darwin_toolchain_no_libcxx \
-// RUN: --check-prefix=CHECK-2 %s
-// CHECK-2: "/usr/bin/ld"
-// CHECK-2: "-lc++" "-lc++experimental"
-// CHECK-2-NOT: "[[TOOLCHAIN]]/usr/lib"
-
-// When we have libc++.dylib in the toolchain, it should be used over the one in the sysroot.
-// There are a few cases worth testing.
-//
-// (1) Without -fexperimental-library.
-// RUN: %clangxx -### %s 2>&1 \
-// RUN: --target=x86_64-apple-darwin \
-// RUN: -ccc-install-dir %S/Inputs/basic_darwin_toolchain/usr/bin \
-// RUN: | FileCheck -DTOOLCHAIN=%S/Inputs/basic_darwin_toolchain \
-// RUN: --check-prefix=CHECK-3 %s
-// CHECK-3: "/usr/bin/ld"
-// CHECK-3: "[[TOOLCHAIN]]/usr/lib/libc++.dylib"
-// CHECK-3-NOT: "-lc++"
-//
-// (2) With -fexperimental-library.
-// RUN: %clangxx -### %s 2>&1 \
-// RUN: --target=x86_64-apple-darwin \
-// RUN: -ccc-install-dir %S/Inputs/basic_darwin_toolchain/usr/bin \
-// RUN: -fexperimental-library \
-// RUN: | FileCheck -DTOOLCHAIN=%S/Inputs/basic_darwin_toolchain \
-// RUN: --check-prefix=CHECK-4 %s
-// CHECK-4: "/usr/bin/ld"
-// CHECK-4: "[[TOOLCHAIN]]/usr/lib/libc++.dylib"
-// CHECK-4: "[[TOOLCHAIN]]/usr/lib/libc++experimental.a"
-// CHECK-4-NOT: "-lc++"
-// CHECK-4-NOT: "-lc++experimental"
-
-// When we have libc++.a in the toolchain instead of libc++.dylib, it should be
-// used over the one in the sysroot.
-//
-// (1) Without -fexperimental-library.
-// RUN: %clangxx -### %s 2>&1 \
-// RUN: --target=x86_64-apple-darwin \
-// RUN: -ccc-install-dir %S/Inputs/basic_darwin_toolchain_static/usr/bin \
-// RUN: | FileCheck -DTOOLCHAIN=%S/Inputs/basic_darwin_toolchain_static \
-// RUN: --check-prefix=CHECK-5 %s
-// CHECK-5: "/usr/bin/ld"
-// CHECK-5: "[[TOOLCHAIN]]/usr/lib/libc++.a"
-// CHECK-5-NOT: "-lc++"
-//
-// (2) With -fexperimental-library.
-// RUN: %clangxx -### %s 2>&1 \
-// RUN: --target=x86_64-apple-darwin \
-// RUN: -ccc-install-dir %S/Inputs/basic_darwin_toolchain_static/usr/bin \
-// RUN: -fexperimental-library \
-// RUN: | FileCheck -DTOOLCHAIN=%S/Inputs/basic_darwin_toolchain_static \
-// RUN: --check-prefix=CHECK-6 %s
-// CHECK-6: "/usr/bin/ld"
-// CHECK-6: "[[TOOLCHAIN]]/usr/lib/libc++.a"
-// CHECK-6: "[[TOOLCHAIN]]/usr/lib/libc++experimental.a"
-// CHECK-6-NOT: "-lc++"
-// CHECK-6-NOT: "-lc++experimental"
diff --git a/clang/test/Driver/experimental-library-flag.cpp b/clang/test/Driver/experimental-library-flag.cpp
index 0546a09d5518b..62b007516897e 100644
--- a/clang/test/Driver/experimental-library-flag.cpp
+++ b/clang/test/Driver/experimental-library-flag.cpp
@@ -18,8 +18,6 @@
// CHECK: -fexperimental-library
// Depending on the stdlib in use, we should (or not) pass -lc++experimental.
-// Note that we don't check for `-lc++experimental` specifically, since some targets
-// like Darwin pass the path to the library explicitly instead of using `-lx`.
-// CHECK-LIBCXX: c++experimental
-// CHECK-LIBSTDCXX-NOT: c++experimental
-// CHECK-NOSTDLIB-NOT: c++experimental
+// CHECK-LIBCXX: -lc++experimental
+// CHECK-LIBSTDCXX-NOT: -lc++experimental
+// CHECK-NOSTDLIB-NOT: -lc++experimental
diff --git a/compiler-rt/cmake/config-ix.cmake b/compiler-rt/cmake/config-ix.cmake
index 30a78b69515cc..084a7060e8d13 100644
--- a/compiler-rt/cmake/config-ix.cmake
+++ b/compiler-rt/cmake/config-ix.cmake
@@ -507,23 +507,8 @@ if(APPLE)
set(CMAKE_OSX_DEPLOYMENT_TARGET "")
set(DARWIN_COMMON_CFLAGS -stdlib=libc++)
-
- # This is tricky: We want to link against libc++, however the libc++ for the
- # architecture we're currently building may not have been built yet, since
- # compiler-rt on Darwin builds for all targets at once while libc++ builds for
- # a single target. Hence, we pass -nostdlib++ to disable the default mechanism
- # for finding libc++, and we pass -lc++ which will end up finding libc++ in the
- # SDK currently in use. That libc++ is the wrong libc++ to use if we're using
- # headers from a just-built libc++, but at least it contains all the architectures
- # we should be interested in.
- #
- # Fixing this properly would require removing the impedence mismatch between
- # the compiler-rt build on Darwin (which wants to build all architectures at
- # once) and the libc++ build, which produces a single architecture per CMake
- # invocation.
set(DARWIN_COMMON_LINK_FLAGS
-stdlib=libc++
- -nostdlib++
-lc++
-lc++abi)
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