Add workaround for rules_foreign_cc

Author: calebzulawski

bazel/detail/tools/BUILD

@@ -74,15 +74,15 @@ EXE_EXT = ".exe" if "windows" in HOST_TARGET else ""
             out = tool + SCRIPT_EXT,
             data = ["@llvm-{}//:bin/{}{}".format(HOST_TARGET, tool, EXE_EXT)],
             substitutions = {
-                "TOOL": "$(execpath @llvm-{}//:bin/{}{})".format(HOST_TARGET, tool, EXE_EXT),
+                "{{TOOL}}": "$(execpath @llvm-{}//:bin/{}{})".format(HOST_TARGET, tool, EXE_EXT),
             },
             template = "wrapper" + SCRIPT_EXT,
         ),
         expand_template(
             name = tool + "_bat",
             out = tool + ".bat",
             substitutions = {
-                "TOOL": tool,
+                "{{TOOL}}": tool,
             },
             template = "wrapper.bat",
         ),

bazel/detail/tools/wrapper.bat

@@ -1,4 +1,4 @@
 @echo off
-powershell -ExecutionPolicy Bypass -File "%~dp0TOOL.ps1" %*
+powershell -ExecutionPolicy Bypass -File "%~dp0{{TOOL}}.ps1" %*
 set exitcode=%errorlevel%
-exit /b %exitcode%
+exit /b %exitcode%

bazel/detail/tools/wrapper.ps1

@@ -1,4 +1,10 @@
-$exe = 'TOOL' -replace '/', '\'
+if ($env:EXT_BUILD_ROOT) {
+    # Workaround for rules_foreign_cc
+    $exe = (Join-Path $env:EXT_BUILD_ROOT '{{TOOL}}') -replace '/', '\'
+} else {
+    $exe = '{{TOOL}}' -replace '/', '\'
+}
+
 $processedArgs = @()
 foreach ($arg in $args) {
     $processedArg = $arg -replace '__BAZEL_EXECUTION_ROOT__', $PWD.Path
@@ -10,4 +16,4 @@ foreach ($arg in $args) {
 $toolExitCode = $LASTEXITCODE
 
 # Exit with the same code as the tool
-exit $toolExitCode
+exit $toolExitCode

bazel/detail/tools/wrapper.sh

@@ -4,4 +4,10 @@ args=()
 for i in "$@"; do
     args+=("${i//__BAZEL_EXECUTION_ROOT__/$PWD}")
 done
-TOOL "${args[@]}"
+
+if [ -z ${EXT_BUILD_ROOT+x} ]; then
+    "{{TOOL}}" "${args[@]}"
+else
+    # workaround for rules_foreign_cc
+    "$EXT_BUILD_ROOT/{{TOOL}}" "${args[@]}"
+fi