llvmPackages_*.libllvm: make llvm-config and llvm-config equivalent

LLVM's build system creates NATIVE/bin/llvm-config by reexecuting cmake
with entirely new flags. Problematically, the `CMAKE_INSTALL_*` flags
are not inherited, causing llvm-config-native to return wrong
installation paths, e. g. CMAKE_INSTALL_LIBDIR would default to `lib64`
on x86_64-linux. Previously this was masked by outputs.patch which
replaced ActiveLibDir with a string passed in from Nix, however
`--cmakedir` for example would turn out to be wrong always, breaking
cross-compilation of e. g. lld.

Additionally LLVM_ENABLE_RTTI needs to be repassed, as it is used to
determine if RTTI is available. Passing LLVM_LINK_LLVM_DYLIB is crucial
if we are building LLVM non-statically: It influences the --shared-mode
flag (which should indicate that -lLLVM is enough to link all
components) and makes --link-shared work in the first place,
i. e. llvm-config-native believes the built shared libs don't exist
unless we repass this flag.

Passing LLVM_LINK_LLVM_DYLIB=ON, however, makes the native build produce
a full libLLVM.so which is something we don't want, so we introduce a
patch which forces llvm-config to link statically against the LLVM
components it needs.

pkgs/development/compilers/llvm/10/llvm/default.nix

@@ -57,6 +57,12 @@ in stdenv.mkDerivation (rec {
   propagatedBuildInputs = [ ncurses zlib ];
 
   patches = [
+    # When cross-compiling we configure llvm-config-native with an approximation
+    # of the flags used for the normal LLVM build. To avoid the need for building
+    # a native libLLVM.so (which would fail) we force llvm-config to be linked
+    # statically against the necessary LLVM components always.
+    ../../llvm-config-link-static.patch
+
     ./gnu-install-dirs.patch
     # On older CPUs (e.g. Hydra/wendy) we'd be getting an error in this test.
     (fetchpatch {
@@ -151,18 +157,28 @@ in stdenv.mkDerivation (rec {
     ln -sv $PWD/lib $out
   '';
 
-  cmakeFlags = with stdenv; [
-    "-DLLVM_INSTALL_CMAKE_DIR=${placeholder "dev"}/lib/cmake/llvm/"
+  cmakeFlags = with stdenv; let
+    # These flags influence llvm-config's BuildVariables.inc in addition to the
+    # general build. We need to make sure these are also passed via
+    # CROSS_TOOLCHAIN_FLAGS_NATIVE when cross-compiling or llvm-config-native
+    # will return different results from the cross llvm-config.
+    #
+    # Some flags don't need to be repassed because LLVM already does so (like
+    # CMAKE_BUILD_TYPE), others are irrelevant to the result.
+    flagsForLlvmConfig = [
+      "-DLLVM_INSTALL_CMAKE_DIR=${placeholder "dev"}/lib/cmake/llvm/"
+      "-DLLVM_ENABLE_RTTI=ON"
+    ] ++ optionals enableSharedLibraries [
+      "-DLLVM_LINK_LLVM_DYLIB=ON"
+    ];
+  in flagsForLlvmConfig ++ [
     "-DCMAKE_BUILD_TYPE=${if debugVersion then "Debug" else "Release"}"
     "-DLLVM_INSTALL_UTILS=ON"  # Needed by rustc
     "-DLLVM_BUILD_TESTS=ON"
     "-DLLVM_ENABLE_FFI=ON"
-    "-DLLVM_ENABLE_RTTI=ON"
     "-DLLVM_HOST_TRIPLE=${stdenv.hostPlatform.config}"
     "-DLLVM_DEFAULT_TARGET_TRIPLE=${stdenv.hostPlatform.config}"
     "-DLLVM_ENABLE_DUMP=ON"
-  ] ++ optionals enableSharedLibraries [
-    "-DLLVM_LINK_LLVM_DYLIB=ON"
   ] ++ optionals enableManpages [
     "-DLLVM_BUILD_DOCS=ON"
     "-DLLVM_ENABLE_SPHINX=ON"
@@ -188,7 +204,21 @@ in stdenv.mkDerivation (rec {
           "-DCMAKE_STRIP=${nativeBintools}/bin/${nativeBintools.targetPrefix}strip"
           "-DCMAKE_RANLIB=${nativeBintools}/bin/${nativeBintools.targetPrefix}ranlib"
         ];
-      in "-DCROSS_TOOLCHAIN_FLAGS_NATIVE:list=${lib.concatStringsSep ";" nativeToolchainFlags}"
+        # We need to repass the custom GNUInstallDirs values, otherwise CMake
+        # will choose them for us, leading to wrong results in llvm-config-native
+        nativeInstallFlags = [
+          "-DCMAKE_INSTALL_PREFIX=${placeholder "out"}"
+          "-DCMAKE_INSTALL_BINDIR=${placeholder "out"}/bin"
+          "-DCMAKE_INSTALL_INCLUDEDIR=${placeholder "dev"}/include"
+          "-DCMAKE_INSTALL_LIBDIR=${placeholder "lib"}/lib"
+          "-DCMAKE_INSTALL_LIBEXECDIR=${placeholder "lib"}/libexec"
+        ];
+      in "-DCROSS_TOOLCHAIN_FLAGS_NATIVE:list="
+      + lib.concatStringsSep ";" (lib.concatLists [
+        flagsForLlvmConfig
+        nativeToolchainFlags
+        nativeInstallFlags
+      ])
     )
   ];
 

pkgs/development/compilers/llvm/11/llvm/default.nix

@@ -57,6 +57,12 @@ in stdenv.mkDerivation (rec {
   propagatedBuildInputs = [ ncurses zlib ];
 
   patches = [
+    # When cross-compiling we configure llvm-config-native with an approximation
+    # of the flags used for the normal LLVM build. To avoid the need for building
+    # a native libLLVM.so (which would fail) we force llvm-config to be linked
+    # statically against the necessary LLVM components always.
+    ../../llvm-config-link-static.patch
+
     ./gnu-install-dirs.patch
     # On older CPUs (e.g. Hydra/wendy) we'd be getting an error in this test.
     (fetchpatch {
@@ -152,18 +158,28 @@ in stdenv.mkDerivation (rec {
   # E.g. mesa.drivers use the build-id as a cache key (see #93946):
   LDFLAGS = optionalString (enableSharedLibraries && !stdenv.isDarwin) "-Wl,--build-id=sha1";
 
-  cmakeFlags = with stdenv; [
-    "-DLLVM_INSTALL_CMAKE_DIR=${placeholder "dev"}/lib/cmake/llvm/"
+  cmakeFlags = with stdenv; let
+    # These flags influence llvm-config's BuildVariables.inc in addition to the
+    # general build. We need to make sure these are also passed via
+    # CROSS_TOOLCHAIN_FLAGS_NATIVE when cross-compiling or llvm-config-native
+    # will return different results from the cross llvm-config.
+    #
+    # Some flags don't need to be repassed because LLVM already does so (like
+    # CMAKE_BUILD_TYPE), others are irrelevant to the result.
+    flagsForLlvmConfig = [
+      "-DLLVM_INSTALL_CMAKE_DIR=${placeholder "dev"}/lib/cmake/llvm/"
+      "-DLLVM_ENABLE_RTTI=ON"
+    ] ++ optionals enableSharedLibraries [
+      "-DLLVM_LINK_LLVM_DYLIB=ON"
+    ];
+  in flagsForLlvmConfig ++ [
     "-DCMAKE_BUILD_TYPE=${if debugVersion then "Debug" else "Release"}"
     "-DLLVM_INSTALL_UTILS=ON"  # Needed by rustc
     "-DLLVM_BUILD_TESTS=ON"
     "-DLLVM_ENABLE_FFI=ON"
-    "-DLLVM_ENABLE_RTTI=ON"
     "-DLLVM_HOST_TRIPLE=${stdenv.hostPlatform.config}"
     "-DLLVM_DEFAULT_TARGET_TRIPLE=${stdenv.hostPlatform.config}"
     "-DLLVM_ENABLE_DUMP=ON"
-  ] ++ optionals enableSharedLibraries [
-    "-DLLVM_LINK_LLVM_DYLIB=ON"
   ] ++ optionals enableManpages [
     "-DLLVM_BUILD_DOCS=ON"
     "-DLLVM_ENABLE_SPHINX=ON"
@@ -189,7 +205,21 @@ in stdenv.mkDerivation (rec {
           "-DCMAKE_STRIP=${nativeBintools}/bin/${nativeBintools.targetPrefix}strip"
           "-DCMAKE_RANLIB=${nativeBintools}/bin/${nativeBintools.targetPrefix}ranlib"
         ];
-      in "-DCROSS_TOOLCHAIN_FLAGS_NATIVE:list=${lib.concatStringsSep ";" nativeToolchainFlags}"
+        # We need to repass the custom GNUInstallDirs values, otherwise CMake
+        # will choose them for us, leading to wrong results in llvm-config-native
+        nativeInstallFlags = [
+          "-DCMAKE_INSTALL_PREFIX=${placeholder "out"}"
+          "-DCMAKE_INSTALL_BINDIR=${placeholder "out"}/bin"
+          "-DCMAKE_INSTALL_INCLUDEDIR=${placeholder "dev"}/include"
+          "-DCMAKE_INSTALL_LIBDIR=${placeholder "lib"}/lib"
+          "-DCMAKE_INSTALL_LIBEXECDIR=${placeholder "lib"}/libexec"
+        ];
+      in "-DCROSS_TOOLCHAIN_FLAGS_NATIVE:list="
+      + lib.concatStringsSep ";" (lib.concatLists [
+        flagsForLlvmConfig
+        nativeToolchainFlags
+        nativeInstallFlags
+      ])
     )
   ];
 

pkgs/development/compilers/llvm/12/llvm/default.nix

@@ -58,6 +58,12 @@ in stdenv.mkDerivation (rec {
     ++ [ zlib ];
 
   patches = [
+    # When cross-compiling we configure llvm-config-native with an approximation
+    # of the flags used for the normal LLVM build. To avoid the need for building
+    # a native libLLVM.so (which would fail) we force llvm-config to be linked
+    # statically against the necessary LLVM components always.
+    ../../llvm-config-link-static.patch
+
     ./gnu-install-dirs.patch
     # On older CPUs (e.g. Hydra/wendy) we'd be getting an error in this test.
     (fetchpatch {
@@ -138,18 +144,28 @@ in stdenv.mkDerivation (rec {
   # E.g. mesa.drivers use the build-id as a cache key (see #93946):
   LDFLAGS = optionalString (enableSharedLibraries && !stdenv.isDarwin) "-Wl,--build-id=sha1";
 
-  cmakeFlags = with stdenv; [
-    "-DLLVM_INSTALL_CMAKE_DIR=${placeholder "dev"}/lib/cmake/llvm/"
+  cmakeFlags = with stdenv; let
+    # These flags influence llvm-config's BuildVariables.inc in addition to the
+    # general build. We need to make sure these are also passed via
+    # CROSS_TOOLCHAIN_FLAGS_NATIVE when cross-compiling or llvm-config-native
+    # will return different results from the cross llvm-config.
+    #
+    # Some flags don't need to be repassed because LLVM already does so (like
+    # CMAKE_BUILD_TYPE), others are irrelevant to the result.
+    flagsForLlvmConfig = [
+      "-DLLVM_INSTALL_CMAKE_DIR=${placeholder "dev"}/lib/cmake/llvm/"
+      "-DLLVM_ENABLE_RTTI=ON"
+    ] ++ optionals enableSharedLibraries [
+      "-DLLVM_LINK_LLVM_DYLIB=ON"
+    ];
+  in flagsForLlvmConfig ++ [
     "-DCMAKE_BUILD_TYPE=${if debugVersion then "Debug" else "Release"}"
     "-DLLVM_INSTALL_UTILS=ON"  # Needed by rustc
     "-DLLVM_BUILD_TESTS=ON"
     "-DLLVM_ENABLE_FFI=ON"
-    "-DLLVM_ENABLE_RTTI=ON"
     "-DLLVM_HOST_TRIPLE=${stdenv.hostPlatform.config}"
     "-DLLVM_DEFAULT_TARGET_TRIPLE=${stdenv.hostPlatform.config}"
     "-DLLVM_ENABLE_DUMP=ON"
-  ] ++ optionals enableSharedLibraries [
-    "-DLLVM_LINK_LLVM_DYLIB=ON"
   ] ++ optionals enableManpages [
     "-DLLVM_BUILD_DOCS=ON"
     "-DLLVM_ENABLE_SPHINX=ON"
@@ -175,7 +191,21 @@ in stdenv.mkDerivation (rec {
           "-DCMAKE_STRIP=${nativeBintools}/bin/${nativeBintools.targetPrefix}strip"
           "-DCMAKE_RANLIB=${nativeBintools}/bin/${nativeBintools.targetPrefix}ranlib"
         ];
-      in "-DCROSS_TOOLCHAIN_FLAGS_NATIVE:list=${lib.concatStringsSep ";" nativeToolchainFlags}"
+        # We need to repass the custom GNUInstallDirs values, otherwise CMake
+        # will choose them for us, leading to wrong results in llvm-config-native
+        nativeInstallFlags = [
+          "-DCMAKE_INSTALL_PREFIX=${placeholder "out"}"
+          "-DCMAKE_INSTALL_BINDIR=${placeholder "out"}/bin"
+          "-DCMAKE_INSTALL_INCLUDEDIR=${placeholder "dev"}/include"
+          "-DCMAKE_INSTALL_LIBDIR=${placeholder "lib"}/lib"
+          "-DCMAKE_INSTALL_LIBEXECDIR=${placeholder "lib"}/libexec"
+        ];
+      in "-DCROSS_TOOLCHAIN_FLAGS_NATIVE:list="
+      + lib.concatStringsSep ";" (lib.concatLists [
+        flagsForLlvmConfig
+        nativeToolchainFlags
+        nativeInstallFlags
+      ])
     )
   ];
 

pkgs/development/compilers/llvm/13/llvm/default.nix

@@ -52,6 +52,12 @@ in stdenv.mkDerivation (rec {
   checkInputs = [ which ];
 
   patches = [
+    # When cross-compiling we configure llvm-config-native with an approximation
+    # of the flags used for the normal LLVM build. To avoid the need for building
+    # a native libLLVM.so (which would fail) we force llvm-config to be linked
+    # statically against the necessary LLVM components always.
+    ../../llvm-config-link-static.patch
+
     ./gnu-install-dirs.patch
 
     # Fix random compiler crashes: https://bugs.llvm.org/show_bug.cgi?id=50611
@@ -104,18 +110,28 @@ in stdenv.mkDerivation (rec {
   # E.g. mesa.drivers use the build-id as a cache key (see #93946):
   LDFLAGS = optionalString (enableSharedLibraries && !stdenv.isDarwin) "-Wl,--build-id=sha1";
 
-  cmakeFlags = with stdenv; [
-    "-DLLVM_INSTALL_CMAKE_DIR=${placeholder "dev"}/lib/cmake/llvm/"
+  cmakeFlags = with stdenv; let
+    # These flags influence llvm-config's BuildVariables.inc in addition to the
+    # general build. We need to make sure these are also passed via
+    # CROSS_TOOLCHAIN_FLAGS_NATIVE when cross-compiling or llvm-config-native
+    # will return different results from the cross llvm-config.
+    #
+    # Some flags don't need to be repassed because LLVM already does so (like
+    # CMAKE_BUILD_TYPE), others are irrelevant to the result.
+    flagsForLlvmConfig = [
+      "-DLLVM_INSTALL_CMAKE_DIR=${placeholder "dev"}/lib/cmake/llvm/"
+      "-DLLVM_ENABLE_RTTI=ON"
+    ] ++ optionals enableSharedLibraries [
+      "-DLLVM_LINK_LLVM_DYLIB=ON"
+    ];
+  in flagsForLlvmConfig ++ [
     "-DCMAKE_BUILD_TYPE=${if debugVersion then "Debug" else "Release"}"
     "-DLLVM_INSTALL_UTILS=ON"  # Needed by rustc
     "-DLLVM_BUILD_TESTS=ON"
     "-DLLVM_ENABLE_FFI=ON"
-    "-DLLVM_ENABLE_RTTI=ON"
     "-DLLVM_HOST_TRIPLE=${stdenv.hostPlatform.config}"
     "-DLLVM_DEFAULT_TARGET_TRIPLE=${stdenv.hostPlatform.config}"
     "-DLLVM_ENABLE_DUMP=ON"
-  ] ++ optionals enableSharedLibraries [
-    "-DLLVM_LINK_LLVM_DYLIB=ON"
   ] ++ optionals enableManpages [
     "-DLLVM_BUILD_DOCS=ON"
     "-DLLVM_ENABLE_SPHINX=ON"
@@ -141,7 +157,21 @@ in stdenv.mkDerivation (rec {
           "-DCMAKE_STRIP=${nativeBintools}/bin/${nativeBintools.targetPrefix}strip"
           "-DCMAKE_RANLIB=${nativeBintools}/bin/${nativeBintools.targetPrefix}ranlib"
         ];
-      in "-DCROSS_TOOLCHAIN_FLAGS_NATIVE:list=${lib.concatStringsSep ";" nativeToolchainFlags}"
+        # We need to repass the custom GNUInstallDirs values, otherwise CMake
+        # will choose them for us, leading to wrong results in llvm-config-native
+        nativeInstallFlags = [
+          "-DCMAKE_INSTALL_PREFIX=${placeholder "out"}"
+          "-DCMAKE_INSTALL_BINDIR=${placeholder "out"}/bin"
+          "-DCMAKE_INSTALL_INCLUDEDIR=${placeholder "dev"}/include"
+          "-DCMAKE_INSTALL_LIBDIR=${placeholder "lib"}/lib"
+          "-DCMAKE_INSTALL_LIBEXECDIR=${placeholder "lib"}/libexec"
+        ];
+      in "-DCROSS_TOOLCHAIN_FLAGS_NATIVE:list="
+      + lib.concatStringsSep ";" (lib.concatLists [
+        flagsForLlvmConfig
+        nativeToolchainFlags
+        nativeInstallFlags
+      ])
     )
   ];
 

pkgs/development/compilers/llvm/5/llvm/default.nix

@@ -65,6 +65,13 @@ stdenv.mkDerivation ({
     #  sha256 = "0injj1hqgrbcbihhwp2nbal88jfykad30r54f2cdcx7gws2fcy8i";
     #  stripLen = 1;
     #})
+
+    # When cross-compiling we configure llvm-config-native with an approximation
+    # of the flags used for the normal LLVM build. To avoid the need for building
+    # a native libLLVM.so (which would fail) we force llvm-config to be linked
+    # statically against the necessary LLVM components always.
+    ../../llvm-config-link-static.patch
+
     ./gnu-install-dirs.patch
 
     # Fix invalid std::string(nullptr) for GCC 12
@@ -124,20 +131,30 @@ stdenv.mkDerivation ({
     ln -sv $PWD/lib $out
   '';
 
-  cmakeFlags = with stdenv; [
-    "-DLLVM_INSTALL_CMAKE_DIR=${placeholder "dev"}/lib/cmake/llvm/"
+  cmakeFlags = with stdenv; let
+    # These flags influence llvm-config's BuildVariables.inc in addition to the
+    # general build. We need to make sure these are also passed via
+    # CROSS_TOOLCHAIN_FLAGS_NATIVE when cross-compiling or llvm-config-native
+    # will return different results from the cross llvm-config.
+    #
+    # Some flags don't need to be repassed because LLVM already does so (like
+    # CMAKE_BUILD_TYPE), others are irrelevant to the result.
+    flagsForLlvmConfig = [
+      "-DLLVM_INSTALL_CMAKE_DIR=${placeholder "dev"}/lib/cmake/llvm/"
+      "-DLLVM_ENABLE_RTTI=ON"
+    ] ++ optionals enableSharedLibraries [
+      "-DLLVM_LINK_LLVM_DYLIB=ON"
+    ];
+  in flagsForLlvmConfig ++ [
     "-DCMAKE_BUILD_TYPE=${if debugVersion then "Debug" else "Release"}"
     "-DLLVM_INSTALL_UTILS=ON"  # Needed by rustc
     "-DLLVM_BUILD_TESTS=ON"
     "-DLLVM_ENABLE_FFI=ON"
-    "-DLLVM_ENABLE_RTTI=ON"
 
     "-DLLVM_HOST_TRIPLE=${stdenv.hostPlatform.config}"
     "-DLLVM_DEFAULT_TARGET_TRIPLE=${stdenv.hostPlatform.config}"
     "-DTARGET_TRIPLE=${stdenv.hostPlatform.config}"
   ]
-  ++ lib.optional enableSharedLibraries
-    "-DLLVM_LINK_LLVM_DYLIB=ON"
   ++ lib.optionals enableManpages [
     "-DLLVM_BUILD_DOCS=ON"
     "-DLLVM_ENABLE_SPHINX=ON"
@@ -164,7 +181,21 @@ stdenv.mkDerivation ({
           "-DCMAKE_STRIP=${nativeBintools}/bin/${nativeBintools.targetPrefix}strip"
           "-DCMAKE_RANLIB=${nativeBintools}/bin/${nativeBintools.targetPrefix}ranlib"
         ];
-      in "-DCROSS_TOOLCHAIN_FLAGS_NATIVE:list=${lib.concatStringsSep ";" nativeToolchainFlags}"
+        # We need to repass the custom GNUInstallDirs values, otherwise CMake
+        # will choose them for us, leading to wrong results in llvm-config-native
+        nativeInstallFlags = [
+          "-DCMAKE_INSTALL_PREFIX=${placeholder "out"}"
+          "-DCMAKE_INSTALL_BINDIR=${placeholder "out"}/bin"
+          "-DCMAKE_INSTALL_INCLUDEDIR=${placeholder "dev"}/include"
+          "-DCMAKE_INSTALL_LIBDIR=${placeholder "lib"}/lib"
+          "-DCMAKE_INSTALL_LIBEXECDIR=${placeholder "lib"}/libexec"
+        ];
+      in "-DCROSS_TOOLCHAIN_FLAGS_NATIVE:list="
+      + lib.concatStringsSep ";" (lib.concatLists [
+        flagsForLlvmConfig
+        nativeToolchainFlags
+        nativeInstallFlags
+      ])
     )
   ];
 

pkgs/development/compilers/llvm/6/llvm/default.nix

@@ -63,6 +63,13 @@ stdenv.mkDerivation ({
       includes = [ "test/tools/gold/X86/common.ll" ];
       sha256 = "0fxgrxmfnjx17w3lcq19rk68b2xksh1bynz3ina784kma7hp4wdb";
     })
+
+    # When cross-compiling we configure llvm-config-native with an approximation
+    # of the flags used for the normal LLVM build. To avoid the need for building
+    # a native libLLVM.so (which would fail) we force llvm-config to be linked
+    # statically against the necessary LLVM components always.
+    ../../llvm-config-link-static.patch
+
     ./gnu-install-dirs.patch
 
     # Fix invalid std::string(nullptr) for GCC 12
@@ -119,19 +126,29 @@ stdenv.mkDerivation ({
     ln -sv $PWD/lib $out
   '';
 
-  cmakeFlags = with stdenv; [
-    "-DLLVM_INSTALL_CMAKE_DIR=${placeholder "dev"}/lib/cmake/llvm/"
+  cmakeFlags = with stdenv; let
+    # These flags influence llvm-config's BuildVariables.inc in addition to the
+    # general build. We need to make sure these are also passed via
+    # CROSS_TOOLCHAIN_FLAGS_NATIVE when cross-compiling or llvm-config-native
+    # will return different results from the cross llvm-config.
+    #
+    # Some flags don't need to be repassed because LLVM already does so (like
+    # CMAKE_BUILD_TYPE), others are irrelevant to the result.
+    flagsForLlvmConfig = [
+      "-DLLVM_INSTALL_CMAKE_DIR=${placeholder "dev"}/lib/cmake/llvm/"
+      "-DLLVM_ENABLE_RTTI=ON"
+    ] ++ optionals enableSharedLibraries [
+      "-DLLVM_LINK_LLVM_DYLIB=ON"
+    ];
+  in flagsForLlvmConfig ++ [
     "-DCMAKE_BUILD_TYPE=${if debugVersion then "Debug" else "Release"}"
     "-DLLVM_INSTALL_UTILS=ON"  # Needed by rustc
     "-DLLVM_BUILD_TESTS=ON"
     "-DLLVM_ENABLE_FFI=ON"
-    "-DLLVM_ENABLE_RTTI=ON"
     "-DLLVM_HOST_TRIPLE=${stdenv.hostPlatform.config}"
     "-DLLVM_DEFAULT_TARGET_TRIPLE=${stdenv.hostPlatform.config}"
     "-DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=WebAssembly"
     "-DLLVM_ENABLE_DUMP=ON"
-  ] ++ optionals enableSharedLibraries [
-    "-DLLVM_LINK_LLVM_DYLIB=ON"
   ] ++ optionals enableManpages [
     "-DLLVM_BUILD_DOCS=ON"
     "-DLLVM_ENABLE_SPHINX=ON"
@@ -157,7 +174,21 @@ stdenv.mkDerivation ({
           "-DCMAKE_STRIP=${nativeBintools}/bin/${nativeBintools.targetPrefix}strip"
           "-DCMAKE_RANLIB=${nativeBintools}/bin/${nativeBintools.targetPrefix}ranlib"
         ];
-      in "-DCROSS_TOOLCHAIN_FLAGS_NATIVE:list=${lib.concatStringsSep ";" nativeToolchainFlags}"
+        # We need to repass the custom GNUInstallDirs values, otherwise CMake
+        # will choose them for us, leading to wrong results in llvm-config-native
+        nativeInstallFlags = [
+          "-DCMAKE_INSTALL_PREFIX=${placeholder "out"}"
+          "-DCMAKE_INSTALL_BINDIR=${placeholder "out"}/bin"
+          "-DCMAKE_INSTALL_INCLUDEDIR=${placeholder "dev"}/include"
+          "-DCMAKE_INSTALL_LIBDIR=${placeholder "lib"}/lib"
+          "-DCMAKE_INSTALL_LIBEXECDIR=${placeholder "lib"}/libexec"
+        ];
+      in "-DCROSS_TOOLCHAIN_FLAGS_NATIVE:list="
+      + lib.concatStringsSep ";" (lib.concatLists [
+        flagsForLlvmConfig
+        nativeToolchainFlags
+        nativeInstallFlags
+      ])
     )
   ];
 

pkgs/development/compilers/llvm/7/llvm/default.nix

@@ -67,6 +67,13 @@ in stdenv.mkDerivation ({
       url = "https://github.com/llvm-mirror/llvm/commit/cc1f2a595ead516812a6c50398f0f3480ebe031f.patch";
       sha256 = "0k6k1p5yisgwx417a67s7sr9930rqh1n0zv5jvply8vjjy4b3kf8";
     })
+
+    # When cross-compiling we configure llvm-config-native with an approximation
+    # of the flags used for the normal LLVM build. To avoid the need for building
+    # a native libLLVM.so (which would fail) we force llvm-config to be linked
+    # statically against the necessary LLVM components always.
+    ../../llvm-config-link-static.patch
+
     ./gnu-install-dirs.patch
 
     # Fix invalid std::string(nullptr) for GCC 12
@@ -138,19 +145,29 @@ in stdenv.mkDerivation ({
     ln -sv $PWD/lib $out
   '';
 
-  cmakeFlags = with stdenv; [
-    "-DLLVM_INSTALL_CMAKE_DIR=${placeholder "dev"}/lib/cmake/llvm/"
+  cmakeFlags = with stdenv; let
+    # These flags influence llvm-config's BuildVariables.inc in addition to the
+    # general build. We need to make sure these are also passed via
+    # CROSS_TOOLCHAIN_FLAGS_NATIVE when cross-compiling or llvm-config-native
+    # will return different results from the cross llvm-config.
+    #
+    # Some flags don't need to be repassed because LLVM already does so (like
+    # CMAKE_BUILD_TYPE), others are irrelevant to the result.
+    flagsForLlvmConfig = [
+      "-DLLVM_INSTALL_CMAKE_DIR=${placeholder "dev"}/lib/cmake/llvm/"
+      "-DLLVM_ENABLE_RTTI=ON"
+    ] ++ optionals enableSharedLibraries [
+      "-DLLVM_LINK_LLVM_DYLIB=ON"
+    ];
+  in flagsForLlvmConfig ++ [
     "-DCMAKE_BUILD_TYPE=${if debugVersion then "Debug" else "Release"}"
     "-DLLVM_INSTALL_UTILS=ON"  # Needed by rustc
     "-DLLVM_BUILD_TESTS=ON"
     "-DLLVM_ENABLE_FFI=ON"
-    "-DLLVM_ENABLE_RTTI=ON"
     "-DLLVM_HOST_TRIPLE=${stdenv.hostPlatform.config}"
     "-DLLVM_DEFAULT_TARGET_TRIPLE=${stdenv.hostPlatform.config}"
     "-DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=WebAssembly"
     "-DLLVM_ENABLE_DUMP=ON"
-  ] ++ optionals enableSharedLibraries [
-    "-DLLVM_LINK_LLVM_DYLIB=ON"
   ] ++ optionals enableManpages [
     "-DLLVM_BUILD_DOCS=ON"
     "-DLLVM_ENABLE_SPHINX=ON"
@@ -176,7 +193,21 @@ in stdenv.mkDerivation ({
           "-DCMAKE_STRIP=${nativeBintools}/bin/${nativeBintools.targetPrefix}strip"
           "-DCMAKE_RANLIB=${nativeBintools}/bin/${nativeBintools.targetPrefix}ranlib"
         ];
-      in "-DCROSS_TOOLCHAIN_FLAGS_NATIVE:list=${lib.concatStringsSep ";" nativeToolchainFlags}"
+        # We need to repass the custom GNUInstallDirs values, otherwise CMake
+        # will choose them for us, leading to wrong results in llvm-config-native
+        nativeInstallFlags = [
+          "-DCMAKE_INSTALL_PREFIX=${placeholder "out"}"
+          "-DCMAKE_INSTALL_BINDIR=${placeholder "out"}/bin"
+          "-DCMAKE_INSTALL_INCLUDEDIR=${placeholder "dev"}/include"
+          "-DCMAKE_INSTALL_LIBDIR=${placeholder "lib"}/lib"
+          "-DCMAKE_INSTALL_LIBEXECDIR=${placeholder "lib"}/libexec"
+        ];
+      in "-DCROSS_TOOLCHAIN_FLAGS_NATIVE:list="
+      + lib.concatStringsSep ";" (lib.concatLists [
+        flagsForLlvmConfig
+        nativeToolchainFlags
+        nativeInstallFlags
+      ])
     )
   ];
 

pkgs/development/compilers/llvm/8/llvm/default.nix

@@ -57,6 +57,12 @@ in stdenv.mkDerivation ({
   propagatedBuildInputs = [ ncurses zlib ];
 
   patches = [
+    # When cross-compiling we configure llvm-config-native with an approximation
+    # of the flags used for the normal LLVM build. To avoid the need for building
+    # a native libLLVM.so (which would fail) we force llvm-config to be linked
+    # statically against the necessary LLVM components always.
+    ../../llvm-config-link-static.patch
+
     # Fix missing includes for GCC 10
     (fetchpatch {
       url = "https://bugs.gentoo.org/attachment.cgi?id=612792";
@@ -133,18 +139,28 @@ in stdenv.mkDerivation ({
     ln -sv $PWD/lib $out
   '';
 
-  cmakeFlags = with stdenv; [
-    "-DLLVM_INSTALL_CMAKE_DIR=${placeholder "dev"}/lib/cmake/llvm/"
+  cmakeFlags = with stdenv; let
+    # These flags influence llvm-config's BuildVariables.inc in addition to the
+    # general build. We need to make sure these are also passed via
+    # CROSS_TOOLCHAIN_FLAGS_NATIVE when cross-compiling or llvm-config-native
+    # will return different results from the cross llvm-config.
+    #
+    # Some flags don't need to be repassed because LLVM already does so (like
+    # CMAKE_BUILD_TYPE), others are irrelevant to the result.
+    flagsForLlvmConfig = [
+      "-DLLVM_INSTALL_CMAKE_DIR=${placeholder "dev"}/lib/cmake/llvm/"
+      "-DLLVM_ENABLE_RTTI=ON"
+    ] ++ optionals enableSharedLibraries [
+      "-DLLVM_LINK_LLVM_DYLIB=ON"
+    ];
+  in flagsForLlvmConfig ++ [
     "-DCMAKE_BUILD_TYPE=${if debugVersion then "Debug" else "Release"}"
     "-DLLVM_INSTALL_UTILS=ON"  # Needed by rustc
     "-DLLVM_BUILD_TESTS=ON"
     "-DLLVM_ENABLE_FFI=ON"
-    "-DLLVM_ENABLE_RTTI=ON"
     "-DLLVM_HOST_TRIPLE=${stdenv.hostPlatform.config}"
     "-DLLVM_DEFAULT_TARGET_TRIPLE=${stdenv.hostPlatform.config}"
     "-DLLVM_ENABLE_DUMP=ON"
-  ] ++ optionals enableSharedLibraries [
-    "-DLLVM_LINK_LLVM_DYLIB=ON"
   ] ++ optionals enableManpages [
     "-DLLVM_BUILD_DOCS=ON"
     "-DLLVM_ENABLE_SPHINX=ON"
@@ -170,7 +186,21 @@ in stdenv.mkDerivation ({
           "-DCMAKE_STRIP=${nativeBintools}/bin/${nativeBintools.targetPrefix}strip"
           "-DCMAKE_RANLIB=${nativeBintools}/bin/${nativeBintools.targetPrefix}ranlib"
         ];
-      in "-DCROSS_TOOLCHAIN_FLAGS_NATIVE:list=${lib.concatStringsSep ";" nativeToolchainFlags}"
+        # We need to repass the custom GNUInstallDirs values, otherwise CMake
+        # will choose them for us, leading to wrong results in llvm-config-native
+        nativeInstallFlags = [
+          "-DCMAKE_INSTALL_PREFIX=${placeholder "out"}"
+          "-DCMAKE_INSTALL_BINDIR=${placeholder "out"}/bin"
+          "-DCMAKE_INSTALL_INCLUDEDIR=${placeholder "dev"}/include"
+          "-DCMAKE_INSTALL_LIBDIR=${placeholder "lib"}/lib"
+          "-DCMAKE_INSTALL_LIBEXECDIR=${placeholder "lib"}/libexec"
+        ];
+      in "-DCROSS_TOOLCHAIN_FLAGS_NATIVE:list="
+      + lib.concatStringsSep ";" (lib.concatLists [
+        flagsForLlvmConfig
+        nativeToolchainFlags
+        nativeInstallFlags
+      ])
     )
   ];
 

pkgs/development/compilers/llvm/9/llvm/default.nix

@@ -57,6 +57,12 @@ in stdenv.mkDerivation (rec {
   propagatedBuildInputs = [ ncurses zlib ];
 
   patches = [
+    # When cross-compiling we configure llvm-config-native with an approximation
+    # of the flags used for the normal LLVM build. To avoid the need for building
+    # a native libLLVM.so (which would fail) we force llvm-config to be linked
+    # statically against the necessary LLVM components always.
+    ../../llvm-config-link-static.patch
+
     ./gnu-install-dirs.patch
     # Force a test to evaluate the saved benchmark for a CPU for which LLVM has
     # an execution model. See NixOS/nixpkgs#119673.
@@ -148,18 +154,28 @@ in stdenv.mkDerivation (rec {
     ln -sv $PWD/lib $out
   '';
 
-  cmakeFlags = with stdenv; [
-    "-DLLVM_INSTALL_CMAKE_DIR=${placeholder "dev"}/lib/cmake/llvm/"
+  cmakeFlags = with stdenv; let
+    # These flags influence llvm-config's BuildVariables.inc in addition to the
+    # general build. We need to make sure these are also passed via
+    # CROSS_TOOLCHAIN_FLAGS_NATIVE when cross-compiling or llvm-config-native
+    # will return different results from the cross llvm-config.
+    #
+    # Some flags don't need to be repassed because LLVM already does so (like
+    # CMAKE_BUILD_TYPE), others are irrelevant to the result.
+    flagsForLlvmConfig = [
+      "-DLLVM_INSTALL_CMAKE_DIR=${placeholder "dev"}/lib/cmake/llvm/"
+      "-DLLVM_ENABLE_RTTI=ON"
+    ] ++ optionals enableSharedLibraries [
+      "-DLLVM_LINK_LLVM_DYLIB=ON"
+    ];
+  in flagsForLlvmConfig ++ [
     "-DCMAKE_BUILD_TYPE=${if debugVersion then "Debug" else "Release"}"
     "-DLLVM_INSTALL_UTILS=ON"  # Needed by rustc
     "-DLLVM_BUILD_TESTS=ON"
     "-DLLVM_ENABLE_FFI=ON"
-    "-DLLVM_ENABLE_RTTI=ON"
     "-DLLVM_HOST_TRIPLE=${stdenv.hostPlatform.config}"
     "-DLLVM_DEFAULT_TARGET_TRIPLE=${stdenv.hostPlatform.config}"
     "-DLLVM_ENABLE_DUMP=ON"
-  ] ++ optionals enableSharedLibraries [
-    "-DLLVM_LINK_LLVM_DYLIB=ON"
   ] ++ optionals enableManpages [
     "-DLLVM_BUILD_DOCS=ON"
     "-DLLVM_ENABLE_SPHINX=ON"
@@ -185,7 +201,21 @@ in stdenv.mkDerivation (rec {
           "-DCMAKE_STRIP=${nativeBintools}/bin/${nativeBintools.targetPrefix}strip"
           "-DCMAKE_RANLIB=${nativeBintools}/bin/${nativeBintools.targetPrefix}ranlib"
         ];
-      in "-DCROSS_TOOLCHAIN_FLAGS_NATIVE:list=${lib.concatStringsSep ";" nativeToolchainFlags}"
+        # We need to repass the custom GNUInstallDirs values, otherwise CMake
+        # will choose them for us, leading to wrong results in llvm-config-native
+        nativeInstallFlags = [
+          "-DCMAKE_INSTALL_PREFIX=${placeholder "out"}"
+          "-DCMAKE_INSTALL_BINDIR=${placeholder "out"}/bin"
+          "-DCMAKE_INSTALL_INCLUDEDIR=${placeholder "dev"}/include"
+          "-DCMAKE_INSTALL_LIBDIR=${placeholder "lib"}/lib"
+          "-DCMAKE_INSTALL_LIBEXECDIR=${placeholder "lib"}/libexec"
+        ];
+      in "-DCROSS_TOOLCHAIN_FLAGS_NATIVE:list="
+      + lib.concatStringsSep ";" (lib.concatLists [
+        flagsForLlvmConfig
+        nativeToolchainFlags
+        nativeInstallFlags
+      ])
     )
   ];
 

pkgs/development/compilers/llvm/git/llvm/default.nix

@@ -51,6 +51,12 @@ in stdenv.mkDerivation (rec {
   checkInputs = [ which ];
 
   patches = [
+    # When cross-compiling we configure llvm-config-native with an approximation
+    # of the flags used for the normal LLVM build. To avoid the need for building
+    # a native libLLVM.so (which would fail) we force llvm-config to be linked
+    # statically against the necessary LLVM components always.
+    ../../llvm-config-link-static.patch
+
     ./gnu-install-dirs.patch
   ] ++ lib.optional enablePolly ./gnu-install-dirs-polly.patch;
 
@@ -96,18 +102,28 @@ in stdenv.mkDerivation (rec {
   # E.g. mesa.drivers use the build-id as a cache key (see #93946):
   LDFLAGS = optionalString (enableSharedLibraries && !stdenv.isDarwin) "-Wl,--build-id=sha1";
 
-  cmakeFlags = with stdenv; [
-    "-DLLVM_INSTALL_CMAKE_DIR=${placeholder "dev"}/lib/cmake/llvm/"
+  cmakeFlags = with stdenv; let
+    # These flags influence llvm-config's BuildVariables.inc in addition to the
+    # general build. We need to make sure these are also passed via
+    # CROSS_TOOLCHAIN_FLAGS_NATIVE when cross-compiling or llvm-config-native
+    # will return different results from the cross llvm-config.
+    #
+    # Some flags don't need to be repassed because LLVM already does so (like
+    # CMAKE_BUILD_TYPE), others are irrelevant to the result.
+    flagsForLlvmConfig = [
+      "-DLLVM_INSTALL_CMAKE_DIR=${placeholder "dev"}/lib/cmake/llvm/"
+      "-DLLVM_ENABLE_RTTI=ON"
+    ] ++ optionals enableSharedLibraries [
+      "-DLLVM_LINK_LLVM_DYLIB=ON"
+    ];
+  in flagsForLlvmConfig ++ [
     "-DCMAKE_BUILD_TYPE=${if debugVersion then "Debug" else "Release"}"
     "-DLLVM_INSTALL_UTILS=ON"  # Needed by rustc
     "-DLLVM_BUILD_TESTS=ON"
     "-DLLVM_ENABLE_FFI=ON"
-    "-DLLVM_ENABLE_RTTI=ON"
     "-DLLVM_HOST_TRIPLE=${stdenv.hostPlatform.config}"
     "-DLLVM_DEFAULT_TARGET_TRIPLE=${stdenv.hostPlatform.config}"
     "-DLLVM_ENABLE_DUMP=ON"
-  ] ++ optionals enableSharedLibraries [
-    "-DLLVM_LINK_LLVM_DYLIB=ON"
   ] ++ optionals enableManpages [
     "-DLLVM_BUILD_DOCS=ON"
     "-DLLVM_ENABLE_SPHINX=ON"
@@ -133,7 +149,21 @@ in stdenv.mkDerivation (rec {
           "-DCMAKE_STRIP=${nativeBintools}/bin/${nativeBintools.targetPrefix}strip"
           "-DCMAKE_RANLIB=${nativeBintools}/bin/${nativeBintools.targetPrefix}ranlib"
         ];
-      in "-DCROSS_TOOLCHAIN_FLAGS_NATIVE:list=${lib.concatStringsSep ";" nativeToolchainFlags}"
+        # We need to repass the custom GNUInstallDirs values, otherwise CMake
+        # will choose them for us, leading to wrong results in llvm-config-native
+        nativeInstallFlags = [
+          "-DCMAKE_INSTALL_PREFIX=${placeholder "out"}"
+          "-DCMAKE_INSTALL_BINDIR=${placeholder "out"}/bin"
+          "-DCMAKE_INSTALL_INCLUDEDIR=${placeholder "dev"}/include"
+          "-DCMAKE_INSTALL_LIBDIR=${placeholder "lib"}/lib"
+          "-DCMAKE_INSTALL_LIBEXECDIR=${placeholder "lib"}/libexec"
+        ];
+      in "-DCROSS_TOOLCHAIN_FLAGS_NATIVE:list="
+      + lib.concatStringsSep ";" (lib.concatLists [
+        flagsForLlvmConfig
+        nativeToolchainFlags
+        nativeInstallFlags
+      ])
     )
   ];
 

pkgs/development/compilers/llvm/llvm-config-link-static.patch

@@ -0,0 +1,12 @@
+diff --git llvm/tools/llvm-config/CMakeLists.txt llvm/tools/llvm-config/CMakeLists.txt
+index 16ba54c0cf2f..20b017195e84 100644
+--- llvm/tools/llvm-config/CMakeLists.txt
++++ llvm/tools/llvm-config/CMakeLists.txt
+@@ -6,6 +6,7 @@ set(BUILDVARIABLES_OBJPATH ${CMAKE_CURRENT_BINARY_DIR}/BuildVariables.inc)
+ # Add the llvm-config tool.
+ add_llvm_tool(llvm-config
+   llvm-config.cpp
++  DISABLE_LLVM_LINK_LLVM_DYLIB
+   )
+ 
+ # Compute the substitution values for various items.