commit 47d94da23587b7343b1fcddf44c2db24f2ed5331
Date:   Fri Dec 4 21:08:59 2020 +0530

    [android] Support building the host tools and with the static stdlib

diff --git a/swift/stdlib/public/runtime/CMakeLists.txt b/swift/stdlib/public/runtime/CMakeLists.txt
index fd8e29ae1a85..b1bc4ea4a92a 100644
--- a/swift/stdlib/public/runtime/CMakeLists.txt
+++ b/swift/stdlib/public/runtime/CMakeLists.txt
@@ -116,7 +116,7 @@ add_swift_target_library(swiftRuntime OBJECT_LIBRARY
 
 set(ELFISH_SDKS)
 set(COFF_SDKS)
-foreach(sdk ${SWIFT_CONFIGURED_SDKS})
+foreach(sdk ${SWIFT_SDKS})
   if("${SWIFT_SDK_${sdk}_OBJECT_FORMAT}" STREQUAL "ELF")
     list(APPEND ELFISH_SDKS ${sdk})
   elseif("${SWIFT_SDK_${sdk}_OBJECT_FORMAT}" STREQUAL "COFF")
@@ -144,7 +144,7 @@ add_swift_target_library(swiftImageRegistrationObjectCOFF
                   SWIFT_COMPILE_FLAGS ${SWIFT_STANDARD_LIBRARY_SWIFT_FLAGS}
                   INSTALL_IN_COMPONENT none)
 
-foreach(sdk ${SWIFT_CONFIGURED_SDKS})
+foreach(sdk ${SWIFT_SDKS})
   foreach(arch ${SWIFT_SDK_${sdk}_ARCHITECTURES})
     set(arch_subdir "${SWIFT_SDK_${sdk}_LIB_SUBDIR}/${arch}")
     set(arch_suffix "${SWIFT_SDK_${sdk}_LIB_SUBDIR}-${arch}")
@@ -224,11 +224,18 @@ foreach(sdk ${SWIFT_CONFIGURED_SDKS})
           set(libicu_data_a ${ICU_UC_LIBDIR}/libicudata.a)
         endif()
       endif()
+      set(libpthread -lpthread)
+      set(android_libraries)
+      if(${sdk} STREQUAL ANDROID)
+        set(android_libraries -llog)
+        set(libpthread)
+      endif()
 
       set(linkfile ${lowercase_sdk}/static-stdlib-args.lnk)
       file(WRITE "${SWIFTSTATICLIB_DIR}/${linkfile}" "
 -ldl
--lpthread
+${libpthread}
+${android_libraries}
 -lswiftCore
 ${libicu_i18n_a}
 ${libicu_uc_a}
diff --git a/swift/utils/build-script-impl b/swift/utils/build-script-impl
index 268d23de155a..d33ab94d1bd8 100755
--- a/swift/utils/build-script-impl
+++ b/swift/utils/build-script-impl
@@ -452,17 +452,35 @@ function set_build_options_for_host() {
     SWIFT_HOST_VARIANT_ARCH=$architecture
 
     case ${host} in
-        android-aarch64)
-            SWIFT_HOST_TRIPLE="aarch64-unknown-linux-android${ANDROID_API_LEVEL}"
-            llvm_target_arch="AArch64"
-            ;;
-        android-armv7)
-            SWIFT_HOST_TRIPLE="armv7-unknown-linux-androideabi${ANDROID_API_LEVEL}"
-            llvm_target_arch="ARM"
-            ;;
-        android-x86_64)
-            SWIFT_HOST_TRIPLE="x86_64-unknown-linux-android${ANDROID_API_LEVEL}"
-            llvm_target_arch="X86"
+        android-*)
+            # Clang uses a different sysroot natively on Android in the Termux
+            # app, which the Termux build scripts pass in through a $PREFIX
+            # variable.
+            if [[ "${PREFIX}" ]] ; then
+                llvm_cmake_options+=(
+                    -DDEFAULT_SYSROOT:STRING="$(dirname ${PREFIX})"
+                )
+            fi
+            # Android doesn't support building all of compiler-rt yet.
+            if [[ ! $(is_cross_tools_host "${host}") ]] ; then
+                llvm_cmake_options+=(
+                    -DCOMPILER_RT_INCLUDE_TESTS:BOOL=FALSE
+                )
+            fi
+            case ${host} in
+                android-aarch64)
+                    SWIFT_HOST_TRIPLE="aarch64-unknown-linux-android${ANDROID_API_LEVEL}"
+                    llvm_target_arch="AArch64"
+                    ;;
+                android-armv7)
+                    SWIFT_HOST_TRIPLE="armv7-unknown-linux-androideabi${ANDROID_API_LEVEL}"
+                    llvm_target_arch="ARM"
+                    ;;
+                android-x86_64)
+                    SWIFT_HOST_TRIPLE="x86_64-unknown-linux-android${ANDROID_API_LEVEL}"
+                    llvm_target_arch="X86"
+                    ;;
+            esac
             ;;
         linux-armv6)
             SWIFT_HOST_TRIPLE="armv6-unknown-linux-gnueabihf"
@@ -1756,7 +1774,8 @@ for host in "${ALL_HOSTS[@]}"; do
                     )
                 fi
 
-                if [[ ! "${SKIP_BUILD_ANDROID}" ]]; then
+                if [[ ! "${SKIP_BUILD_ANDROID}" ]] ||
+                   [[ $(is_cross_tools_host ${host}) && "${host}" == "android-"* ]]; then
                     cmake_options=(
                         "${cmake_options[@]}"
                         -DSWIFT_ANDROID_NDK_PATH:STRING="${ANDROID_NDK}"
@@ -2447,6 +2466,8 @@ for host in "${ALL_HOSTS[@]}"; do
             elif [[ "$(uname -s)" == "Haiku" ]] ; then
               HOST_CXX_HEADERS_DIR="/boot/system/develop/headers/c++"
             elif [[ "${ANDROID_DATA}" ]] ; then
+              # This means we're building natively on Android in the Termux
+              # app, which supplies the $PREFIX variable.
               HOST_CXX_HEADERS_DIR="$PREFIX/include/c++"
             else # Linux
               HOST_CXX_HEADERS_DIR="/usr/include/c++"