https://github.com/ldionne updated https://github.com/llvm/llvm-project/pull/170912
>From 12a532cc430c3b89483ce9cc89bbfc7bea8541e5 Mon Sep 17 00:00:00 2001 From: Kewen Meng <[email protected]> Date: Fri, 5 Dec 2025 12:01:47 -0800 Subject: [PATCH 1/3] =?UTF-8?q?Revert=20"[clang][Darwin]=20Prefer=20the=20?= =?UTF-8?q?toolchain-provided=20libc++.dylib=20if=20there=20i=E2=80=A6"?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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) >From 3ac8417fb4d6d0916cf5082d76d9794420a9cd8e Mon Sep 17 00:00:00 2001 From: Louis Dionne <[email protected]> Date: Fri, 5 Dec 2025 15:19:05 -0500 Subject: [PATCH 2/3] =?UTF-8?q?Reapply=20"[clang][Darwin]=20Prefer=20the?= =?UTF-8?q?=20toolchain-provided=20libc++.dylib=20if=20there=20i=E2=80=A6"?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This reverts commit 12a532cc430c3b89483ce9cc89bbfc7bea8541e5. --- 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, 144 insertions(+), 8 deletions(-) create mode 100644 clang/test/Driver/Inputs/basic_darwin_toolchain/usr/lib/libc++.dylib create mode 100644 clang/test/Driver/Inputs/basic_darwin_toolchain/usr/lib/libc++experimental.a create mode 100644 clang/test/Driver/Inputs/basic_darwin_toolchain_static/usr/bin/.keep create mode 100644 clang/test/Driver/Inputs/basic_darwin_toolchain_static/usr/include/c++/v1/.keep create mode 100644 clang/test/Driver/Inputs/basic_darwin_toolchain_static/usr/lib/libc++.a create mode 100644 clang/test/Driver/Inputs/basic_darwin_toolchain_static/usr/lib/libc++experimental.a create 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 fc3cd9030f71d..30c53389dc22f 100644 --- a/clang/lib/Driver/ToolChains/Darwin.cpp +++ b/clang/lib/Driver/ToolChains/Darwin.cpp @@ -2846,11 +2846,49 @@ void AppleMachO::AddCXXStdlibLibArgs(const ArgList &Args, CXXStdlibType Type = GetCXXStdlibType(Args); switch (Type) { - case ToolChain::CST_Libcxx: - CmdArgs.push_back("-lc++"); + 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++"); if (Args.hasArg(options::OPT_fexperimental_library)) - CmdArgs.push_back("-lc++experimental"); + Link("c++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 new file mode 100644 index 0000000000000..e69de29bb2d1d 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 new file mode 100644 index 0000000000000..e69de29bb2d1d 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 new file mode 100644 index 0000000000000..e69de29bb2d1d 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 new file mode 100644 index 0000000000000..e69de29bb2d1d 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 new file mode 100644 index 0000000000000..e69de29bb2d1d 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 new file mode 100644 index 0000000000000..e69de29bb2d1d diff --git a/clang/test/Driver/darwin-header-search-libcxx.cpp b/clang/test/Driver/darwin-header-search-libcxx.cpp index cc8ec9ceb89b3..e8985a4e22b2f 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 -nostdlib will drop both the toolchain +// Make sure that using -nostdinc, -nostdinc++ or -nostdlibinc 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 \ +// RUN: | FileCheck -DSYSROOT=%S/Inputs/basic_darwin_sdk_usr_cxx_v1 \ // 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 new file mode 100644 index 0000000000000..1c4f31b257512 --- /dev/null +++ b/clang/test/Driver/darwin-link-libcxx.cpp @@ -0,0 +1,81 @@ +// 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 62b007516897e..0546a09d5518b 100644 --- a/clang/test/Driver/experimental-library-flag.cpp +++ b/clang/test/Driver/experimental-library-flag.cpp @@ -18,6 +18,8 @@ // CHECK: -fexperimental-library // Depending on the stdlib in use, we should (or not) pass -lc++experimental. -// CHECK-LIBCXX: -lc++experimental -// CHECK-LIBSTDCXX-NOT: -lc++experimental -// CHECK-NOSTDLIB-NOT: -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 diff --git a/compiler-rt/cmake/config-ix.cmake b/compiler-rt/cmake/config-ix.cmake index 084a7060e8d13..30a78b69515cc 100644 --- a/compiler-rt/cmake/config-ix.cmake +++ b/compiler-rt/cmake/config-ix.cmake @@ -507,8 +507,23 @@ 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) >From 4c50d83e8ddecf0cf6f642671523e14770d1c3e7 Mon Sep 17 00:00:00 2001 From: Louis Dionne <[email protected]> Date: Fri, 5 Dec 2025 15:23:05 -0500 Subject: [PATCH 3/3] Require darwin --- clang/test/Driver/darwin-link-libcxx.cpp | 3 +++ 1 file changed, 3 insertions(+) diff --git a/clang/test/Driver/darwin-link-libcxx.cpp b/clang/test/Driver/darwin-link-libcxx.cpp index 1c4f31b257512..fca1e3c6f3d6f 100644 --- a/clang/test/Driver/darwin-link-libcxx.cpp +++ b/clang/test/Driver/darwin-link-libcxx.cpp @@ -1,5 +1,8 @@ // UNSUPPORTED: system-windows +// TODO: Make this test portable across platforms +// REQUIRES: system-darwin + // 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. _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
