build: allow configuration of the system header location

Rather than hardcoding the paths to /usr/include, allow the user to set
the path to their libc headers.  This is particularly important for
environments which may not use the traditional layout (e.g. exherbo) or
for builds which wish to build against an out-of-tree, non-system
installed libc for a Unix target which does not match the host system
(i.e. foreign cross-compilation).

Author: compnerd

cmake/modules/SwiftConfigureSDK.cmake

@@ -61,6 +61,10 @@ function(_report_sdk prefix)
   endif()
 
   if(NOT prefix IN_LIST SWIFT_APPLE_PLATFORMS)
+    foreach(arch ${SWIFT_SDK_${prefix}_ARCHITECTURES})
+      message(STATUS "  ${arch} libc header path: ${SWIFT_SDK_${prefix}_ARCH_${arch}_LIBC_INCLUDE_DIRECTORY}")
+      message(STATUS "  ${arch} libc architecture specific header path: ${SWIFT_SDK_${prefix}_ARCH_${arch}_LIBC_ARCHITECTURE_INCLUDE_DIRECTORY}")
+    endforeach()
     if(SWIFT_BUILD_STDLIB)
       foreach(arch ${SWIFT_SDK_${prefix}_ARCHITECTURES})
         message(STATUS "  ${arch} ICU i18n INCLUDE: ${SWIFT_${prefix}_${arch}_ICU_I18N_INCLUDE}")
@@ -200,6 +204,9 @@ macro(configure_sdk_unix name architectures)
 
   foreach(arch ${architectures})
     if("${prefix}" STREQUAL "ANDROID")
+      set(SWIFT_SDK_ANDROID_ARCH_${arch}_LIBC_INCLUDE_DIRECTORY "${SWIFT_ANDROID_NDK_PATH}/sysroot/usr/include" CACHE STRING "Path to C library headers")
+      set(SWIFT_SDK_ANDROID_ARCH_${arch}_LIBC_ARCHITECTURE_INCLUDE_DIRECTORY "${SWIFT_ANDROID_NDK_PATH}/sysroot/usr/include" CACHE STRING "Path to C library architecture headers")
+
       if("${arch}" STREQUAL "armv7")
         set(SWIFT_SDK_ANDROID_ARCH_${arch}_NDK_TRIPLE "arm-linux-androideabi")
         set(SWIFT_SDK_ANDROID_ARCH_${arch}_ALT_SPELLING "arm")
@@ -248,6 +255,13 @@ macro(configure_sdk_unix name architectures)
       if(NOT SWIFT_SDK_${prefix}_ARCH_${arch}_PATH)
         set(SWIFT_SDK_${prefix}_ARCH_${arch}_PATH "/")
       endif()
+      if("${prefix}" STREQUAL "HAIKU")
+        set(SWIFT_SDK_HAIKU_ARCH_${arch}_LIBC_INCLUDE_DIRECTORY "/system/develop/headers/posix" CACHE STRING "Path to C library headers")
+        set(SWIFT_SDK_HAIKU_ARCH_${arch}_LIBC_ARCHITECTURE_INCLUDE_DIRECTORY "/system/develop/headers" CACHE STRING "Path to C library architecture headers")
+      else()
+        set(SWIFT_SDK_${prefix}_ARCH_${arch}_LIBC_INCLUDE_DIRECTORY "/usr/include" CACHE STRING "Path to C library headers")
+        set(SWIFT_SDK_${prefix}_ARCH_${arch}_LIBC_ARCHITECTURE_INCLUDE_DIRECTORY "${SWIFT_SDK_${prefix}_ARCH_${arch}_LIBC_INCLUDE_DIRECTORY}/${CMAKE_LIBRARY_ARCHITECTURE}" CACHE STRING "Path to C library architecture headers")
+      endif()
 
       if("${prefix}" STREQUAL "LINUX")
         if(arch MATCHES "(armv6|armv7)")

stdlib/public/Platform/CMakeLists.txt

@@ -67,34 +67,6 @@ foreach(sdk ${SWIFT_SDKS})
     set(arch_subdir "${SWIFT_SDK_${sdk}_LIB_SUBDIR}/${arch}")
     set(module_dir "${SWIFTLIB_DIR}/${arch_subdir}")
 
-    if("${sdk}" STREQUAL "HAIKU")
-      # Haiku doesn't have /usr/include, instead the headers are located
-      # at /system/develop/headers.
-      set(GLIBC_INCLUDE_PATH "/system/develop/headers/posix")
-      set(GLIBC_ARCH_INCLUDE_PATH "/system/develop/headers/posix")
-      set(GLIBC_SYSROOT_RELATIVE_ARCH_INCLUDE_PATH "/system/develop/headers/")
-    elseif("${sdk}" STREQUAL "ANDROID")
-      set(GLIBC_SYSROOT_RELATIVE_INCLUDE_PATH "${SWIFT_ANDROID_NDK_PATH}/sysroot/usr/include")
-      set(GLIBC_SYSROOT_RELATIVE_ARCH_INCLUDE_PATH "${SWIFT_ANDROID_NDK_PATH}/sysroot/usr/include")
-    else()
-      # Determine the location of glibc headers based on the target.
-      set(GLIBC_SYSROOT_RELATIVE_INCLUDE_PATH "/usr/include")
-      set(GLIBC_SYSROOT_RELATIVE_ARCH_INCLUDE_PATH "${GLIBC_SYSROOT_RELATIVE_INCLUDE_PATH}")
-    endif()
-
-    # Some SDKs place their headers in architecture-specific subfolders.
-    if((${sdk} STREQUAL "LINUX" OR ${sdk} STREQUAL "FREEBSD") AND CMAKE_LIBRARY_ARCHITECTURE)
-      set(GLIBC_SYSROOT_RELATIVE_ARCH_INCLUDE_PATH "${GLIBC_SYSROOT_RELATIVE_ARCH_INCLUDE_PATH}/${CMAKE_LIBRARY_ARCHITECTURE}")
-    endif()
-
-    set(GLIBC_INCLUDE_PATH "${GLIBC_SYSROOT_RELATIVE_INCLUDE_PATH}")
-    set(GLIBC_ARCH_INCLUDE_PATH "${GLIBC_SYSROOT_RELATIVE_ARCH_INCLUDE_PATH}")
-
-    if(NOT "${SWIFT_SDK_${sdk}_ARCH_${arch}_PATH}" STREQUAL "/" AND NOT "${sdk}" STREQUAL "ANDROID")
-      set(GLIBC_INCLUDE_PATH "${SWIFT_SDK_${sdk}_ARCH_${arch}_PATH}${GLIBC_INCLUDE_PATH}")
-      set(GLIBC_ARCH_INCLUDE_PATH "${SWIFT_SDK_${sdk}_ARCH_${arch}_PATH}${GLIBC_ARCH_INCLUDE_PATH}")
-    endif()
-
     if(${sdk} STREQUAL ANDROID)
       set(glibc_modulemap_source "bionic.modulemap.gyb")
     else()
@@ -111,23 +83,21 @@ foreach(sdk ${SWIFT_SDKS})
         OUTPUT "${glibc_modulemap_out}"
         FLAGS
             "-DCMAKE_SDK=${sdk}"
-            "-DGLIBC_INCLUDE_PATH=${GLIBC_INCLUDE_PATH}"
-            "-DGLIBC_ARCH_INCLUDE_PATH=${GLIBC_ARCH_INCLUDE_PATH}")
+            "-DGLIBC_INCLUDE_PATH=${SWIFT_SDK_${SWIFT_HOST_VARIANT_SDK}_ARCH_${arch}_PATH}${SWIFT_SDK_${sdk}_ARCH_${arch}_LIBC_INCLUDE_DIRECTORY}"
+            "-DGLIBC_ARCH_INCLUDE_PATH=${SWIFT_SDK_${SWIFT_HOST_VARIANT_SDK}_ARCH_${arch}_PATH}${SWIFT_SDK_${sdk}_ARCH_${arch}_LIBC_ARCHITECTURE_INCLUDE_DIRECTORY}")
 
     list(APPEND glibc_modulemap_target_list ${glibc_modulemap_target})
 
     # If this SDK is a target for a non-native host, create a native modulemap
     # without a sysroot prefix. This is the one we'll install instead.
     if(NOT "${SWIFT_SDK_${SWIFT_HOST_VARIANT_SDK}_ARCH_${arch}_PATH}" STREQUAL "/")
-
       set(glibc_sysroot_relative_modulemap_out "${module_dir}/sysroot-relative-modulemaps/glibc.modulemap")
       handle_gyb_source_single(glibc_modulemap_native_target
-          SOURCE "${glibc_modulemap_source}"
-          OUTPUT "${glibc_sysroot_relative_modulemap_out}"
-          FLAGS
-              "-DCMAKE_SDK=${sdk}"
-              "-DGLIBC_INCLUDE_PATH=${GLIBC_SYSROOT_RELATIVE_INCLUDE_PATH}"
-              "-DGLIBC_ARCH_INCLUDE_PATH=${GLIBC_SYSROOT_RELATIVE_ARCH_INCLUDE_PATH}")
+        SOURCE "${glibc_modulemap_source}"
+        OUTPUT "${glibc_sysroot_relative_modulemap_out}"
+        FLAGS "-DCMAKE_SDK=${sdk}"
+              "-DGLIBC_INCLUDE_PATH=${SWIFT_SDK_${sdk}_ARCH_${arch}_LIBC_INCLUDE_DIRECTORY}"
+              "-DGLIBC_ARCH_INCLUDE_PATH=${SWIFT_SDK_${sdk}_ARCH_${arch}_LIBC_ARCHITECTURE_INCLUDE_DIRECTORY}")
 
       list(APPEND glibc_modulemap_target_list ${glibc_modulemap_native_target})
       set(glibc_modulemap_out ${glibc_sysroot_relative_modulemap_out})