Test CL to demonstrate GN + hermetic toolchain

build/toolchain/mac/BUILD.gn

Index: build/toolchain/mac/BUILD.gn
diff --git a/build/toolchain/mac/BUILD.gn b/build/toolchain/mac/BUILD.gn
index 0c00e995fffe139ac39badd12790acbad3a78a7a..31a5419a2ee807d012a13544ee87c5960ad18e8b 100644
--- a/build/toolchain/mac/BUILD.gn
+++ b/build/toolchain/mac/BUILD.gn
@@ -62,6 +62,7 @@ tool_versions =
 # build args in this definition.
 template("mac_toolchain") {
   toolchain(target_name) {
+    env_wrapper = "export DEVELOPER_DIR=$hermetic_xcode_path; "  # Note trailing space.
     # When invoking this toolchain not as the default one, these args will be
     # passed to the build. They are ignored when this is the default toolchain.
     assert(defined(invoker.toolchain_args),
@@ -157,7 +158,7 @@ template("mac_toolchain") {
     tool("cc") {
       depfile = "{{output}}.d"
       precompiled_header_type = "gcc"
-      command = "$cc -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_c}} -c {{source}} -o {{output}}"
+      command = "$env_wrapper $cc -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_c}} -c {{source}} -o {{output}}"
       depsformat = "gcc"
       description = "CC {{output}}"
       outputs = [
@@ -168,7 +169,7 @@ template("mac_toolchain") {
     tool("cxx") {
       depfile = "{{output}}.d"
       precompiled_header_type = "gcc"
-      command = "$cxx -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_cc}} -c {{source}} -o {{output}}"
+      command = "$env_wrapper $cxx -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_cc}} -c {{source}} -o {{output}}"
       depsformat = "gcc"
       description = "CXX {{output}}"
       outputs = [
@@ -179,7 +180,7 @@ template("mac_toolchain") {
     tool("asm") {
       # For GCC we can just use the C compiler to compile assembly.
       depfile = "{{output}}.d"
-      command = "$cc -MMD -MF $depfile {{defines}} {{include_dirs}} {{asmflags}} -c {{source}} -o {{output}}"
+      command = "$env_wrapper $cc -MMD -MF $depfile {{defines}} {{include_dirs}} {{asmflags}} -c {{source}} -o {{output}}"
       depsformat = "gcc"
       description = "ASM {{output}}"
       outputs = [
@@ -190,7 +191,7 @@ template("mac_toolchain") {
     tool("objc") {
       depfile = "{{output}}.d"
       precompiled_header_type = "gcc"
-      command = "$cc -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_objc}} -c {{source}} -o {{output}}"
+      command = "$env_wrapper $cc -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_objc}} -c {{source}} -o {{output}}"
       depsformat = "gcc"
       description = "OBJC {{output}}"
       outputs = [
@@ -201,7 +202,7 @@ template("mac_toolchain") {
     tool("objcxx") {
       depfile = "{{output}}.d"
       precompiled_header_type = "gcc"
-      command = "$cxx -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_objcc}} -c {{source}} -o {{output}}"
+      command = "$env_wrapper $cxx -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_objcc}} -c {{source}} -o {{output}}"
       depsformat = "gcc"
       description = "OBJCXX {{output}}"
       outputs = [
@@ -212,7 +213,7 @@ template("mac_toolchain") {
     tool("alink") {
       script =
           rebase_path("//build/toolchain/mac/filter_libtool.py", root_build_dir)
-      command = "rm -f {{output}} && TOOL_VERSION=${tool_versions.filter_libtool} python $script libtool -static {{arflags}} -o {{output}} {{inputs}}"
+      command = "$env_wrapper rm -f {{output}} && TOOL_VERSION=${tool_versions.filter_libtool} python $script libtool -static {{arflags}} -o {{output}} {{inputs}}"
       description = "LIBTOOL-STATIC {{output}}"
       outputs = [
         "{{output_dir}}/{{target_output_name}}{{output_extension}}",
@@ -240,7 +241,7 @@ template("mac_toolchain") {
 
       does_reexport_command = "[ ! -e \"$dylib\" -o ! -e \"$tocname\" ] || otool -l \"$dylib\" | grep -q LC_REEXPORT_DYLIB"
 
-      link_command = "$linker_driver $ld -shared "
+      link_command = "$env_wrapper $linker_driver $ld -shared "
       if (is_component_build) {
         link_command += " -Wl,-install_name,@rpath/\"{{target_output_name}}{{output_extension}}\" "
       }
@@ -291,7 +292,7 @@ template("mac_toolchain") {
       rspfile = sofile + ".rsp"
       pool = "//build/toolchain:link_pool($default_toolchain)"
 
-      link_command = "$linker_driver $ld -bundle {{ldflags}} -o \"$sofile\" -Wl,-filelist,\"$rspfile\""
+      link_command = "$env_wrapper $linker_driver $ld -bundle {{ldflags}} -o \"$sofile\" -Wl,-filelist,\"$rspfile\""
       if (is_component_build) {
         link_command += " -Wl,-install_name,@rpath/{{target_output_name}}{{output_extension}}"
       }
@@ -334,7 +335,7 @@ template("mac_toolchain") {
       # do for command-line arguments. Thus any source names with spaces, or
       # label names with spaces (which GN bases the output paths on) will be
       # corrupted by this process. Don't use spaces for source files or labels.
-      command = "$linker_driver $ld $dsym_switch {{ldflags}} -o \"$outfile\" -Wl,-filelist,\"$rspfile\" {{solibs}} {{libs}}"
+      command = "$env_wrapper $linker_driver $ld $dsym_switch {{ldflags}} -o \"$outfile\" -Wl,-filelist,\"$rspfile\" {{solibs}} {{libs}}"
       description = "LINK $outfile"
       rspfile_content = "{{inputs_newline}}"
       outputs = [
@@ -400,7 +401,7 @@ template("mac_toolchain") {
         _sdk_name = mac_sdk_name
         _min_deployment_target = mac_deployment_target
       }
-      command = "rm -f {{output}} && " +
+      command = "$env_wrapper rm -f {{output}} && " +
                 "TOOL_VERSION=${tool_versions.compile_xcassets} " +
                 "python $_tool -p $_sdk_name -t $_min_deployment_target " +
                 "-T {{bundle_product_type}} -o {{output}} {{inputs}}"