Overlays: Add Glibc Linux SDK overlay build

Adding a new glibc overlay for Linux builds. We will eventually need one
for Musl, and if someone really wants to, LLVM and cosmopolitan libcs
are also out there.

Author: etcwilde

Runtimes/Overlay/CMakeLists.txt

@@ -99,9 +99,11 @@ endif()
 add_subdirectory(clang)
 if(ANDROID)
   add_subdirectory(Android)
-endif()
-if(WIN32)
+elseif(WIN32)
   add_subdirectory(Windows)
+elseif(LINUX)
+  defaulted_set(SwiftOverlay_LINUX_LIBC STRING "Select Linux libc flavor. Options are: glibc")
+  add_subdirectory("Linux/${SwiftOverlay_LINUX_LIBC}")
 endif()
 
 if(SwiftOverlay_ENABLE_CXX_INTEROP)

Runtimes/Overlay/Linux/glibc/CMakeLists.txt

@@ -0,0 +1,35 @@
+add_subdirectory(clang)
+
+gyb_expand(Glibc.swift.gyb Glibc.swift)
+gyb_expand(tgmath.swift.gyb tgmath.swift)
+
+add_library(swiftGlibc
+  Glibc.swift
+  POSIXError.swift
+  Platform.swift
+  TiocConstants.swift
+  tgmath.swift)
+
+target_link_libraries(swiftGlibc
+  PRIVATE
+    swiftCore
+    SwiftGlibcClangOverlay)
+
+set_target_properties(swiftGlibc PROPERTIES
+  Swift_MODULE_NAME Glibc)
+
+target_compile_options(swiftGlibc PRIVATE
+  "SHELL:-Xcc -fno-omit-frame-pointer"
+  "SHELL:-Xfrontend -empty-abi-descriptor"
+  "SHELL:-Xfrontend -prespecialize-generic-metadata"
+  "SHELL:-Xfrontend -require-explicit-availability=ignore"
+  "SHELL:-library-level api")
+
+install(TARGETS swiftGlibc
+  EXPORT SwiftOverlayTargets
+  ARCHIVE DESTINATION "${SwiftOverlay_INSTALL_LIBDIR}"
+  LIBRARY DESTINATION "${SwiftOverlay_INSTALL_LIBDIR}"
+  RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}")
+emit_swift_interface(swiftGlibc)
+install_swift_interface(swiftGlibc)
+embed_manifest(swiftGlibc)

Runtimes/Overlay/Linux/glibc/clang/CMakeLists.txt

@@ -0,0 +1,36 @@
+gyb_expand(glibc.modulemap.gyb glibc.modulemap
+  FLAGS -DCMAKE_SDK="LINUX")
+gyb_expand(SwiftGlibc.h.gyb SwiftGlibc.h)
+
+file(CONFIGURE
+  OUTPUT glibc-overlay.yml
+  CONTENT [==[
+---
+version: 0
+case-sensitive: false
+use-external-names: false
+roots:
+  - name: "/usr/include"
+    type: directory
+    contents:
+      - name: module.modulemap
+        type: file
+        external-contents: "@CMAKE_CURRENT_BINARY_DIR@/glibc.modulemap"
+      - name: SwiftGlibc.h
+        type: file
+        external-contents: "@CMAKE_CURRENT_BINARY_DIR@/SwiftGlibc.h"
+]==]
+  ESCAPE_QUOTES @ONLY NEWLINE_STYLE LF)
+
+add_library(SwiftGlibcClangOverlay INTERFACE
+  SwiftGlibc.h
+  glibc.modulemap)
+target_compile_options(SwiftGlibcClangOverlay INTERFACE
+  "$<BUILD_INTERFACE:$<$<COMPILE_LANGUAGE:Swift>:SHELL:-vfsoverlay ${CMAKE_CURRENT_BINARY_DIR}/glibc-overlay.yml>>")
+
+install(
+  FILES
+    "${CMAKE_CURRENT_BINARY_DIR}/glibc.modulemap"
+    "${CMAKE_CURRENT_BINARY_DIR}/SwiftGlibc.h"
+  DESTINATION
+    "${CMAKE_INSTALL_LIBDIR}/swift/${SwiftOverlay_PLATFORM_SUBDIR}/${SwiftOverlay_ARCH_SUBDIR}")

Runtimes/Overlay/cmake/modules/DefaultSettings.cmake

@@ -30,9 +30,14 @@ if(APPLE)
 elseif(CMAKE_SYSTEM_NAME STREQUAL "WASM")
   set(SwiftOverlay_ENABLE_REFLECTION_default OFF)
   set(SwiftOverlay_ENABLE_CXX_INTEROP_default OFF)
-elseif(LINUX OR ANDROID OR BSD)
+elseif(ANDROID OR BSD)
   set(SwiftOverlay_ENABLE_REFLECTION_default OFF)
   set(SwiftOverlay_ENABLE_CXX_INTEROP_default OFF)
+elseif(LINUX)
+  # TODO: Enable once we have them building
+  set(SwiftOverlay_ENABLE_REFLECTION_default OFF)
+  set(SwiftOverlay_ENABLE_CXX_INTEROP_default OFF)
+  set(SwiftOverlay_LINUX_LIBC_default "glibc")
 elseif(WIN32)
   set(SwiftOverlay_ENABLE_REFLECTION_default ON)
   set(SwiftOverlay_ENABLE_CXX_INTEROP_default OFF)

Runtimes/Resync.cmake

@@ -150,6 +150,22 @@ copy_files(public/Platform Overlay/Android/Math
   FILES
     Math.swift)
 
+# Linux Glibc Overlay
+message(STATUS "Glibc modulemaps[${StdlibSources}/Platform] -> ${CMAKE_CURRENT_LIST_DIR}/Overlay/Linux/glibc/clang")
+copy_files(public/Platform Overlay/Linux/glibc/clang
+  FILES
+    glibc.modulemap.gyb
+    SwiftGlibc.h.gyb)
+
+message(STATUS "Glibc [${StdlibSources}/Platform] -> ${CMAKE_CURRENT_LIST_DIR}/Overlay/Linux/glibc")
+copy_files(public/Platform Overlay/Linux/glibc
+  FILES
+    Glibc.swift.gyb
+    POSIXError.swift
+    Platform.swift
+    TiocConstants.swift
+    tgmath.swift.gyb)
+
 # Windows Overlay
 message(STATUS "WinSDK[${StdlibSources}/public/Windows] -> ${CMAKE_CURRENT_LIST_DIR}/Overlay/Windows/WinSDK")
 copy_files(public/Windows Overlay/Windows/WinSDK FILES WinSDK.swift)