swift: split build & Darwin support.

pkgs/development/compilers/swift/compiler/patches/clang-wrap.patch

@@ -0,0 +1,18 @@
+Wrap the clang produced during the build
+
+--- a/tools/driver/CMakeLists.txt
++++ b/tools/driver/CMakeLists.txt
+@@ -59,6 +59,13 @@ endif()
+
+ add_dependencies(clang clang-resource-headers)
+
++# Nix: wrap the clang build.
++add_custom_command(
++  TARGET clang POST_BUILD
++  COMMAND nix-swift-make-clang-wrapper $<TARGET_FILE:clang>
++  VERBATIM
++)
++
+ if(NOT CLANG_LINKS_TO_CREATE)
+   set(CLANG_LINKS_TO_CREATE clang++ clang-cl clang-cpp)
+ endif()

pkgs/development/compilers/swift/compiler/patches/llvm-module-cache.patch

@@ -0,0 +1,30 @@
+The compiler fails if LLVM modules are enabled and it cannot write its module
+cache. This patch detects and rejects the fake, non-existant $HOME used in Nix
+builds.
+
+We could simply return false in `cache_directory`, but that completely disables
+module caching, and may unnecessarily slow down builds. Instead, let it use
+'/tmp/.cache'.
+
+--- a/lib/Support/Unix/Path.inc
++++ b/lib/Support/Unix/Path.inc
+@@ -1380,6 +1380,9 @@ bool user_config_directory(SmallVectorImpl<char> &result) {
+   if (!home_directory(result)) {
+     return false;
+   }
++  if (std::equal(result.begin(), result.end(), "/homeless-shelter")) {
++    return false;
++  }
+   append(result, ".config");
+   return true;
+ }
+@@ -1401,6 +1404,9 @@ bool cache_directory(SmallVectorImpl<char> &result) {
+   if (!home_directory(result)) {
+     return false;
+   }
++  if (std::equal(result.begin(), result.end(), "/homeless-shelter")) {
++    system_temp_directory(true/*ErasedOnReboot*/, result);
++  }
+   append(result, ".cache");
+   return true;
+ }

pkgs/development/compilers/swift/compiler/patches/swift-darwin-fix-bootstrap.patch

@@ -0,0 +1,20 @@
+This patch fixes dylib references during bootstrapping. It's possible
+`LIBSWIFT_BUILD_MODE=BOOTSTRAPPING` is not really well tested on Darwin,
+because official builds don't use it.
+
+In the near future, Swift will require an existing Swift toolchain to
+bootstrap, and we will likely have to replace this any way.
+
+--- a/stdlib/cmake/modules/AddSwiftStdlib.cmake
++++ b/stdlib/cmake/modules/AddSwiftStdlib.cmake
+@@ -1035,6 +1035,10 @@ function(add_swift_target_library_single target name)
+       set(install_name_dir "${SWIFTLIB_SINGLE_DARWIN_INSTALL_NAME_DIR}")
+     endif()
+
++    if(DEFINED SWIFTLIB_SINGLE_BOOTSTRAPPING)
++      set(install_name_dir "${lib_dir}/${output_sub_dir}")
++    endif()
++
+     set_target_properties("${target}"
+       PROPERTIES
+       INSTALL_NAME_DIR "${install_name_dir}")

pkgs/development/compilers/swift/compiler/patches/swift-darwin-plistbuddy-workaround.patch

@@ -0,0 +1,17 @@
+CMake tries to read a list field from SDKSettings.plist, but the output of
+facebook/xcbuild PlistBuddy is incompatible with Apple's.
+
+Simply set the supported architectures to the one target architecture we're
+building for.
+
+--- a/cmake/modules/SwiftConfigureSDK.cmake
++++ b/cmake/modules/SwiftConfigureSDK.cmake
+@@ -189,7 +189,7 @@ macro(configure_sdk_darwin
+   endif()
+
+   # Remove any architectures not supported by the SDK.
+-  remove_sdk_unsupported_archs(${name} ${xcrun_name} ${SWIFT_SDK_${prefix}_PATH} SWIFT_SDK_${prefix}_ARCHITECTURES)
++  set(SWIFT_SDK_${prefix}_ARCHITECTURES "@swiftArch@")
+
+   list_intersect(
+     "${SWIFT_DARWIN_MODULE_ARCHS}"            # lhs

pkgs/development/compilers/swift/compiler/patches/swift-linux-fix-linking.patch

@@ -0,0 +1,21 @@
+--- a/lib/Driver/ToolChains.cpp
++++ b/lib/Driver/ToolChains.cpp
+@@ -1475,7 +1475,17 @@ const char *ToolChain::getClangLinkerDriver(
+
+     // If there is a linker driver in the toolchain folder, use that instead.
+     if (auto tool = llvm::sys::findProgramByName(LinkerDriver, {toolchainPath}))
+-      LinkerDriver = Args.MakeArgString(tool.get());
++      return Args.MakeArgString(tool.get());
++  }
++
++  // For Nix, prefer linking using the wrapped system clang, instead of using
++  // the unwrapped clang packaged with swift. The latter is unable to link, but
++  // we still want to use it for other purposes (clang importer).
++  if (auto nixCC = llvm::sys::Process::GetEnv("NIX_CC")) {
++    llvm::SmallString<128> binDir(nixCC.getValue());
++    llvm::sys::path::append(binDir, "bin");
++    if (auto tool = llvm::sys::findProgramByName(LinkerDriver, {binDir.str()}))
++      return Args.MakeArgString(tool.get());
+   }
+
+   return LinkerDriver;

pkgs/development/compilers/swift/compiler/patches/swift-nix-resource-root.patch

@@ -0,0 +1,67 @@
+Swift normally looks for the Clang resource dir in a subdir/symlink of its own
+resource dir. We provide a symlink to the Swift build-time Clang as a default
+there, but we also here patch two checks to try locate it via NIX_CC.
+
+The first (ClangImporter.cpp) happens when Swift code imports C modules. The
+second (ToolChains.cpp) happens when Swift is used to link the final product.
+
+--- a/lib/ClangImporter/ClangImporter.cpp
++++ b/lib/ClangImporter/ClangImporter.cpp
+@@ -68,6 +68,7 @@
+ #include "llvm/Support/FileSystem.h"
+ #include "llvm/Support/Memory.h"
+ #include "llvm/Support/Path.h"
++#include "llvm/Support/Process.h"
+ #include "llvm/Support/YAMLParser.h"
+ #include "llvm/Support/YAMLTraits.h"
+ #include <algorithm>
+@@ -809,6 +810,17 @@ importer::addCommonInvocationArguments(
+
+   const std::string &overrideResourceDir = importerOpts.OverrideResourceDir;
+   if (overrideResourceDir.empty()) {
++    // Prefer the Clang resource directory from NIX_CC, to allow swapping in a
++    // different stdenv.
++    // TODO: Figure out how to provide a user override for this. Probably a
++    // niche use case, though, and for now a user can unset NIX_CC to work
++    // around it if necessary.
++    if (auto nixCC = llvm::sys::Process::GetEnv("NIX_CC")) {
++      llvm::SmallString<128> resourceDir(nixCC.getValue());
++      llvm::sys::path::append(resourceDir, "resource-root");
++      invocationArgStrs.push_back("-resource-dir");
++      invocationArgStrs.push_back(std::string(resourceDir.str()));
++    } else {
+     llvm::SmallString<128> resourceDir(searchPathOpts.RuntimeResourcePath);
+
+     // Adjust the path to refer to our copy of the Clang resource directory
+@@ -824,6 +836,7 @@ importer::addCommonInvocationArguments(
+     // Set the Clang resource directory to the path we computed.
+     invocationArgStrs.push_back("-resource-dir");
+     invocationArgStrs.push_back(std::string(resourceDir.str()));
++    } // nixCC
+   } else {
+     invocationArgStrs.push_back("-resource-dir");
+     invocationArgStrs.push_back(overrideResourceDir);
+--- a/lib/Driver/ToolChains.cpp
++++ b/lib/Driver/ToolChains.cpp
+@@ -1372,10 +1372,20 @@ void ToolChain::getClangLibraryPath(const ArgList &Args,
+                                     SmallString<128> &LibPath) const {
+   const llvm::Triple &T = getTriple();
+
++  // Nix: We provide a `clang` symlink in the default Swift resource root, but
++  // prefer detecting the Clang resource root via NIX_CC, to allow swapping in
++  // a different stdenv. However, always honor a user-provided `-resource-dir`.
++  auto nixCC = llvm::sys::Process::GetEnv("NIX_CC");
++  if (nixCC && !Args.hasArgNoClaim(options::OPT_resource_dir)) {
++    LibPath.assign(nixCC.getValue());
++    llvm::sys::path::append(LibPath, "resource-root");
++  } else {
+   getResourceDirPath(LibPath, Args, /*Shared=*/true);
+   // Remove platform name.
+   llvm::sys::path::remove_filename(LibPath);
+-  llvm::sys::path::append(LibPath, "clang", "lib",
++  llvm::sys::path::append(LibPath, "clang");
++  } // nixCC
++  llvm::sys::path::append(LibPath, "lib",
+                           T.isOSDarwin() ? "darwin"
+                                          : getPlatformNameForTriple(T));
+ }

pkgs/development/compilers/swift/compiler/patches/swift-prevent-sdk-dirs-warning.patch

@@ -0,0 +1,39 @@
+Prevents a user-visible warning on every compilation:
+
+  ld: warning: directory not found for option '-L.../MacOSX11.0.sdk/usr/lib/swift'
+
+--- a/lib/Driver/ToolChains.cpp
++++ b/lib/Driver/ToolChains.cpp
+@@ -1455,9 +1455,11 @@ void ToolChain::getRuntimeLibraryPaths(SmallVectorImpl<std::string> &runtimeLibP
+       runtimeLibPaths.push_back(std::string(scratchPath.str()));
+     }
+
++    if (!SDKPath.startswith("@storeDir@")) {
+     scratchPath = SDKPath;
+     llvm::sys::path::append(scratchPath, "usr", "lib", "swift");
+     runtimeLibPaths.push_back(std::string(scratchPath.str()));
++    }
+   }
+ }
+
+--- a/lib/Frontend/CompilerInvocation.cpp
++++ b/lib/Frontend/CompilerInvocation.cpp
+@@ -185,7 +185,9 @@ static void updateRuntimeLibraryPaths(SearchPathOptions &SearchPathOpts,
+       RuntimeLibraryImportPaths.push_back(std::string(LibPath.str()));
+     }
+
+-    LibPath = SearchPathOpts.getSDKPath();
++    auto SDKPath = SearchPathOpts.getSDKPath();
++    if (!SDKPath.startswith("@storeDir@")) {
++    LibPath = SDKPath;
+     llvm::sys::path::append(LibPath, "usr", "lib", "swift");
+     if (!Triple.isOSDarwin()) {
+       // Use the non-architecture suffixed form with directory-layout
+@@ -200,6 +202,7 @@ static void updateRuntimeLibraryPaths(SearchPathOptions &SearchPathOpts,
+       llvm::sys::path::append(LibPath, swift::getMajorArchitectureName(Triple));
+     }
+     RuntimeLibraryImportPaths.push_back(std::string(LibPath.str()));
++    }
+   }
+   SearchPathOpts.setRuntimeLibraryImportPaths(RuntimeLibraryImportPaths);
+ }

pkgs/development/compilers/swift/compiler/patches/swift-separate-lib.patch

@@ -0,0 +1,26 @@
+Patch paths to use the separate 'lib' output. One of the things this patch
+fixes is the output of `swift -frontend -print-target-info`, which swiftpm uses
+to set rpath on Linux.
+
+The check if the executable path starts with 'out' is necessary for
+bootstrapping, or the compiler will fail when run from the build directory.
+
+--- a/lib/Frontend/CompilerInvocation.cpp
++++ b/lib/Frontend/CompilerInvocation.cpp
+@@ -49,11 +49,16 @@ swift::CompilerInvocation::CompilerInvocation() {
+ void CompilerInvocation::computeRuntimeResourcePathFromExecutablePath(
+     StringRef mainExecutablePath, bool shared,
+     llvm::SmallVectorImpl<char> &runtimeResourcePath) {
++  if (mainExecutablePath.startswith("@storeDir@")) {
++    auto libPath = StringRef("@lib@");
++    runtimeResourcePath.append(libPath.begin(), libPath.end());
++  } else {
+   runtimeResourcePath.append(mainExecutablePath.begin(),
+                              mainExecutablePath.end());
+
+   llvm::sys::path::remove_filename(runtimeResourcePath); // Remove /swift
+   llvm::sys::path::remove_filename(runtimeResourcePath); // Remove /bin
++  }
+   appendSwiftLibDir(runtimeResourcePath, shared);
+ }
+

pkgs/development/compilers/swift/compiler/patches/swift-wrap.patch

@@ -0,0 +1,46 @@
+Wrap the swift compiler produced during the build
+
+--- a/tools/driver/CMakeLists.txt
++++ b/tools/driver/CMakeLists.txt
+@@ -16,6 +16,13 @@ if(${LIBSWIFT_BUILD_MODE} MATCHES "BOOTSTRAPPING.*")
+                           swiftDriverTool
+                           libswiftStub)
+
++  # Nix: wrap the swift build.
++  add_custom_command(
++    TARGET swift-frontend-bootstrapping0 POST_BUILD
++    COMMAND nix-swift-make-swift-wrapper $<TARGET_FILE:swift-frontend-bootstrapping0>
++    VERBATIM
++  )
++
+   swift_create_post_build_symlink(swift-frontend-bootstrapping0
+     SOURCE "swift-frontend${CMAKE_EXECUTABLE_SUFFIX}"
+     DESTINATION "swiftc${CMAKE_EXECUTABLE_SUFFIX}"
+@@ -34,6 +41,13 @@ if(${LIBSWIFT_BUILD_MODE} MATCHES "BOOTSTRAPPING.*")
+                           swiftDriverTool
+                           libswift-bootstrapping1)
+
++  # Nix: wrap the swift build.
++  add_custom_command(
++    TARGET swift-frontend-bootstrapping1 POST_BUILD
++    COMMAND nix-swift-make-swift-wrapper $<TARGET_FILE:swift-frontend-bootstrapping1>
++    VERBATIM
++  )
++
+   swift_create_post_build_symlink(swift-frontend-bootstrapping1
+     SOURCE "swift-frontend${CMAKE_EXECUTABLE_SUFFIX}"
+     DESTINATION "swiftc${CMAKE_EXECUTABLE_SUFFIX}"
+@@ -50,6 +64,13 @@ target_link_libraries(swift-frontend
+                         swiftDriverTool
+                         libswift)
+
++# Nix: wrap the swift build.
++add_custom_command(
++  TARGET swift-frontend POST_BUILD
++  COMMAND nix-swift-make-swift-wrapper $<TARGET_FILE:swift-frontend>
++  VERBATIM
++)
++
+ # Create a `swift-driver` executable adjacent to the `swift-frontend` executable
+ # to ensure that `swiftc` forwards to the standalone driver when invoked.
+ swift_create_early_driver_copies(swift-frontend)