CHANGELOG.md

+# [1.0.0-alpha.2](https://git.gitlab.arm.com/bazel/rules_toolchain/compare/v1.0.0-alpha.1...v1.0.0-alpha.2) (2023-11-16)
+
+### Bug Fixes
+
+- **resolved:** forward on `basename` attribute ([e71e807](https://git.gitlab.arm.com/bazel/rules_toolchain/commit/e71e807b6ded13a3baf2d430900f675a1f8849fd))
+- **test:** correctly output `stderr` from toolchain executable on error ([22cd108](https://git.gitlab.arm.com/bazel/rules_toolchain/commit/22cd108126e8917d7142d7f447fdc61f69ea2521))
+
+### Features
+
+- **local_which:** make local binaries non-mandatory ([5d9a292](https://git.gitlab.arm.com/bazel/rules_toolchain/commit/5d9a292cfd4a7f9dd5b952ca33c34b01da0fc796))
+
 # 1.0.0-alpha.1 (2023-11-15)
 
 ### Bug Fixes

MODULE.bazel

 module(
     name = "rules_toolchain",
-    version = "1.0.0-alpha.1",
+    version = "1.0.0-alpha.2",
     bazel_compatibility = [
         ">=6.4.0",
     ],

e2e/MODULE.bazel.lock

@@ -777,7 +777,7 @@
   "moduleExtensions": {
     "//:MODULE.bazel%_repo_rules": {
       "general": {
-        "bzlTransitiveDigest": "da/DoHSQBm39DhgiqteTa0XULbwxsr8VGJ6XQ/cPUmw=",
+        "bzlTransitiveDigest": "/xroDvlQ7p867k7lShdRN/8y8PAICvIR2NWA0F7JzLg=",
         "accumulatedFileDigests": {},
         "envVariables": {},
         "generatedRepoSpecs": {

package-lock.json

@@ -9,7 +9,7 @@
         "@semantic-release/bzlmod": "https://gitlab.arm.com/semantic-release/bzlmod/-/releases/v1.0.3/downloads/package.tar.gz",
         "@semantic-release/changelog": "^6",
         "@semantic-release/commit-analyzer": "^11",
-        "@semantic-release/config-gitlab-bzlmod": "https://gitlab.arm.com/semantic-release/config-gitlab-bzlmod/-/releases/v1.0.5/downloads/package.tar.gz",
+        "@semantic-release/config-gitlab-bzlmod": "https://gitlab.arm.com/semantic-release/config-gitlab-bzlmod/-/releases/v1.0.6/downloads/package.tar.gz",
         "@semantic-release/config-release-channels": "https://gitlab.arm.com/semantic-release/config-release-channels/-/releases/v1.0.1/downloads/package.tar.gz",
         "@semantic-release/error": "^4",
         "@semantic-release/exec": "^6",
@@ -366,9 +366,9 @@
       }
     },
     "node_modules/@semantic-release/config-gitlab-bzlmod": {
-      "version": "1.0.5",
-      "resolved": "https://gitlab.arm.com/semantic-release/config-gitlab-bzlmod/-/releases/v1.0.5/downloads/package.tar.gz",
-      "integrity": "sha512-crGLBTi9zN0X6Y1ZY9eaaNB3tNGrlx53NMseaGUMIbidlqWJm0rtNI7fRWW6aaI04//iNNpbrp3lyb1zI+34kQ==",
+      "version": "1.0.6",
+      "resolved": "https://gitlab.arm.com/semantic-release/config-gitlab-bzlmod/-/releases/v1.0.6/downloads/package.tar.gz",
+      "integrity": "sha512-y/LRDh7DxjUYCs54OYQ7nREM+v63PhAak9KnOPGSE57nI+sEPAWnMlSnt+zrmXKEhTU+I12EAsmqs6rjNg/6zQ==",
       "dev": true,
       "license": "MIT",
       "peerDependencies": {

package.json

@@ -5,7 +5,7 @@
     "@semantic-release/bzlmod": "https://gitlab.arm.com/semantic-release/bzlmod/-/releases/v1.0.3/downloads/package.tar.gz",
     "@semantic-release/changelog": "^6",
     "@semantic-release/commit-analyzer": "^11",
-    "@semantic-release/config-gitlab-bzlmod": "https://gitlab.arm.com/semantic-release/config-gitlab-bzlmod/-/releases/v1.0.5/downloads/package.tar.gz",
+    "@semantic-release/config-gitlab-bzlmod": "https://gitlab.arm.com/semantic-release/config-gitlab-bzlmod/-/releases/v1.0.6/downloads/package.tar.gz",
     "@semantic-release/config-release-channels": "https://gitlab.arm.com/semantic-release/config-release-channels/-/releases/v1.0.1/downloads/package.tar.gz",
     "@semantic-release/error": "^4",
     "@semantic-release/exec": "^6",

toolchain/local/which/BUILD.tmpl.bazel

@@ -12,5 +12,6 @@ toolchain_symlink_path(
 
 resolved(
     name = "resolved",
-    toolchain = "{{toolchain_type}}",
+    basename = "{{basename}}",
+    toolchain_type = "{{toolchain_type}}",
 )

toolchain/local/which/repository.bzl

+load("//toolchain:resolved.bzl", _ATTRS = "ATTRS")
+
 visibility("//toolchain/...")
 
 DOC = """Creates a repository that provides a binary target wrapping a local binary found on `PATH`.
@@ -17,7 +19,7 @@ toolchain(
 ```
 """
 
-ATTRS = {
+ATTRS = _ATTRS | {
     "program": attr.string(
         doc = "The name of the binary to find on `PATH`.",
     ),
@@ -27,9 +29,9 @@ ATTRS = {
     "variable": attr.string(
         doc = "The variable name for Make or the execution environment.",
     ),
-    "toolchain_type": attr.label(
-        doc = "The toolchain type for the binary.",
-        mandatory = True,
+    "mandatory": attr.bool(
+        doc = "Determines if the tool must exist locally",
+        default = False,
     ),
     "resolved": attr.label(
         doc = "The tepmlate that is expanded into the `resolved.bzl`.",
@@ -41,6 +43,13 @@ ATTRS = {
         default = ":BUILD.tmpl.bazel",
         allow_single_file = True,
     ),
+    "stub": attr.label(
+        doc = "An executable to use when the local binary is not found on `PATH`.",
+        default = ":stub.sh",
+        allow_single_file = True,
+        executable = True,
+        cfg = "exec",
+    ),
 }
 
 def implementation(rctx):
@@ -48,10 +57,13 @@ def implementation(rctx):
 
     path = rctx.which(program)
     if not path:
-        fail("Cannot find `{}` on `PATH`".format(program))
+        if rctx.attr.mandatory:
+            fail("Cannot find `{}` on `PATH`".format(program))
+        path = rctx.path(rctx.attr.stub)
 
     rctx.template("resolved.bzl", rctx.attr.resolved, {
         "{{toolchain_type}}": str(rctx.attr.toolchain_type),
+        "{{basename}}": str(rctx.attr.basename),
     }, executable = False)
 
     rctx.template("BUILD.bazel", rctx.attr.build, {

toolchain/resolved.bzl

@@ -17,7 +17,7 @@ ATTRS = {
     "basename": attr.string(
         doc = "The basename for the symlink, which defaults to `name`",
     ),
-    "toolchain": attr.label(
+    "toolchain_type": attr.label(
         doc = "The toolchain type to resolve and forward on providers.",
         mandatory = True,
     ),
@@ -25,7 +25,7 @@ ATTRS = {
 
 def implementation(ctx):
     basename = ctx.attr.basename or ctx.label.name
-    toolchain = ctx.toolchains[ctx.attr.toolchain.label]
+    toolchain = ctx.toolchains[ctx.attr.toolchain_type.label]
 
     executable = ctx.actions.declare_file(basename)
     ctx.actions.symlink(
@@ -82,7 +82,7 @@ def macro(*, toolchain_type):
 
     resolved(
         name = "resolved",
-        toolchain = ":type",
+        toolchain_type = ":type",
     )
     ```
 

toolchain/resolved/BUILD.tmpl.bazel

@@ -2,6 +2,7 @@ load("//:resolved.bzl", "resolved")
 
 resolved(
     name = "resolved",
-    toolchain = "{{toolchain_type}}",
+    basename = "{{basename}}",
+    toolchain_type = "{{toolchain_type}}",
     visibility = ["//visibility:public"],
 )

toolchain/resolved/repository.bzl

+load("//toolchain:resolved.bzl", _ATTRS = "ATTRS")
+
 visibility("//toolchain/...")
 
 DOC = """Creates a repository that provides a toolchain resolution rule.
@@ -14,11 +16,7 @@ toolchain_resolved(
 [quirk]: https://github.com/bazelbuild/bazel/issues/14009
 """
 
-ATTRS = {
-    "toolchain_type": attr.label(
-        doc = "The toolchain type to resolve.",
-        mandatory = True,
-    ),
+ATTRS = _ATTRS | {
     "resolved": attr.label(
         doc = "The template that is expanded into the `resolved.bzl`.",
         default = Label(":resolved.tmpl.bzl"),
@@ -34,6 +32,7 @@ ATTRS = {
 def implementation(rctx):
     substitutions = {
         "{{toolchain_type}}": str(rctx.attr.toolchain_type),
+        "{{basename}}": str(rctx.attr.basename),
     }
     rctx.template("resolved.bzl", rctx.attr.resolved, substitutions, executable = False)
     rctx.template("BUILD.bazel", rctx.attr.build, substitutions, executable = False)

toolchain/test/posix.tmpl.sh

@@ -24,7 +24,7 @@ if ! "${EXECUTABLE}" "${@}" >stdout.txt 2>stderr.txt; then
   echo >&2 "stderr:"
   while IFS= read -r LINE; do
     echo >&2 "${LINE}"
-  done <stdout.txt
+  done <stderr.txt
   exit 2
 fi