CHANGELOG.md

+# [1.0.0-alpha.10](https://git.gitlab.arm.com/bazel/rules_toolchain/compare/v1.0.0-alpha.9...v1.0.0-alpha.10) (2023-12-13)
+
+### Features
+
+- make `which` mandatory ([274d2c9](https://git.gitlab.arm.com/bazel/rules_toolchain/commit/274d2c96991ea897a76055527561e5346402792a))
+
 # [1.0.0-alpha.9](https://git.gitlab.arm.com/bazel/rules_toolchain/compare/v1.0.0-alpha.8...v1.0.0-alpha.9) (2023-12-13)
 
 ### Bug Fixes

MODULE.bazel

 module(
     name = "rules_toolchain",
-    version = "1.0.0-alpha.9",
+    version = "1.0.0-alpha.10",
     bazel_compatibility = [
         ">=7.0.0",
     ],

README.md

@@ -9,7 +9,12 @@ Add the following to `MODULE.bazel`:
 ```py
 which = use_repo_rule("@rules_toolchain//toolchain/local/which:defs.bzl", "toolchain_local_which")
 which(
-    name = "echo",
+    name = "which",
+)
+
+resolved = use_repo_rule("@rules_toolchain//toolchain/resolved:defs.bzl", "toolchain_resolved")
+resolved(
+    name = "resolved",
     toolchain_type = "//toolchain/echo:type",
 )
 ```
@@ -29,7 +34,7 @@ toolchain_type(
 # No `exec_compatible_with` constraints are needed as a local binary is always compatible with the execution platform
 toolchain(
     name = "local",
-    toolchain = "@echo//:echo",
+    toolchain = "@which//:echo",
     toolchain_type = ":type",
 )
 
@@ -37,7 +42,7 @@ toolchain(
 #   bazel run -- //toolchain/echo:resolved
 alias(
     name = "resolved",
-    actual = "@echo//:resolved",
+    actual = "@resolved",
 )
 
 # Performs a execution test of the binary

e2e/MODULE.bazel

@@ -15,14 +15,13 @@ local_path_override(
 which = use_repo_rule("@rules_toolchain//toolchain/local/which:defs.bzl", "toolchain_local_which")
 
 which(
-    name = "echo",
-    toolchain_type = "//toolchain/echo:type",
+    name = "which-echo",
 )
 
 resolved = use_repo_rule("@rules_toolchain//toolchain/resolved:defs.bzl", "toolchain_resolved")
 
 resolved(
-    name = "resolved",
+    name = "resolved-echo",
     toolchain_type = "//toolchain/echo:type",
 )
 

e2e/MODULE.bazel.lock

 {
   "lockFileVersion": 3,
-  "moduleFileHash": "b5e5212db85ac60ce843baccd184e5d16937d6d310b430f73224a70d9bf8cfa1",
+  "moduleFileHash": "3c21bacae5326234a6afdf5d19ca2491b22cb87d53c9c262c9ede6b26281c4d0",
   "flags": {
     "cmdRegistries": [
       "https://bcr.bazel.build/"
@@ -37,8 +37,8 @@
             "column": 0
           },
           "imports": {
-            "echo": "echo",
-            "resolved": "resolved",
+            "which-echo": "which-echo",
+            "resolved-echo": "resolved-echo",
             "fixture-amd64-linux-gnu": "fixture-amd64-linux-gnu",
             "fixture-arm64-linux-gnu": "fixture-arm64-linux-gnu",
             "fixture-arm-linux-musl": "fixture-arm-linux-musl",
@@ -51,8 +51,7 @@
             {
               "tagName": "@rules_toolchain//toolchain/local/which:defs.bzl%toolchain_local_which",
               "attributeValues": {
-                "toolchain_type": "//toolchain/echo:type",
-                "name": "echo"
+                "name": "which-echo"
               },
               "devDependency": false,
               "location": {
@@ -65,12 +64,12 @@
               "tagName": "@rules_toolchain//toolchain/resolved:defs.bzl%toolchain_resolved",
               "attributeValues": {
                 "toolchain_type": "//toolchain/echo:type",
-                "name": "resolved"
+                "name": "resolved-echo"
               },
               "devDependency": false,
               "location": {
                 "file": "@@//:MODULE.bazel",
-                "line": 24,
+                "line": 23,
                 "column": 9
               }
             },
@@ -82,7 +81,7 @@
               "devDependency": false,
               "location": {
                 "file": "@@//:MODULE.bazel",
-                "line": 33,
+                "line": 32,
                 "column": 8
               }
             },
@@ -94,7 +93,7 @@
               "devDependency": false,
               "location": {
                 "file": "@@//:MODULE.bazel",
-                "line": 37,
+                "line": 36,
                 "column": 8
               }
             },
@@ -106,7 +105,7 @@
               "devDependency": false,
               "location": {
                 "file": "@@//:MODULE.bazel",
-                "line": 41,
+                "line": 40,
                 "column": 8
               }
             },
@@ -118,7 +117,7 @@
               "devDependency": false,
               "location": {
                 "file": "@@//:MODULE.bazel",
-                "line": 45,
+                "line": 44,
                 "column": 8
               }
             },
@@ -130,7 +129,7 @@
               "devDependency": false,
               "location": {
                 "file": "@@//:MODULE.bazel",
-                "line": 49,
+                "line": 48,
                 "column": 8
               }
             },
@@ -148,7 +147,7 @@
               "devDependency": false,
               "location": {
                 "file": "@@//:MODULE.bazel",
-                "line": 55,
+                "line": 54,
                 "column": 7
               }
             }
@@ -162,7 +161,7 @@
           "usingModule": "<root>",
           "location": {
             "file": "@@//:MODULE.bazel",
-            "line": 65,
+            "line": 64,
             "column": 23
           },
           "imports": {
@@ -179,7 +178,7 @@
               "devDependency": false,
               "location": {
                 "file": "@@//:MODULE.bazel",
-                "line": 66,
+                "line": 65,
                 "column": 15
               }
             }
@@ -848,24 +847,23 @@
   "moduleExtensions": {
     "//:MODULE.bazel%_repo_rules": {
       "general": {
-        "bzlTransitiveDigest": "0/0JKbXjdx0+MCsL4hbq33HmaZLsejCHZ1wZeOcD9Es=",
+        "bzlTransitiveDigest": "DcS7hkCR97tWU6RFIoqiRZfRyhn8MoWr0X40xcNtOZg=",
         "accumulatedFileDigests": {},
         "envVariables": {},
         "generatedRepoSpecs": {
-          "echo": {
+          "which-echo": {
             "bzlFile": "@@rules_toolchain~override//toolchain/local/which:repository.bzl",
             "ruleClassName": "which",
             "attributes": {
-              "toolchain_type": "@@//toolchain/echo:type",
-              "name": "_main~_repo_rules~echo"
+              "name": "_main~_repo_rules~which-echo"
             }
           },
-          "resolved": {
+          "resolved-echo": {
             "bzlFile": "@@rules_toolchain~override//toolchain/resolved:repository.bzl",
             "ruleClassName": "resolved",
             "attributes": {
               "toolchain_type": "@@//toolchain/echo:type",
-              "name": "_main~_repo_rules~resolved"
+              "name": "_main~_repo_rules~resolved-echo"
             }
           },
           "fixture-amd64-linux-gnu": {

e2e/toolchain/echo/BUILD.bazel

@@ -9,7 +9,7 @@ toolchain_type(
 
 toolchain(
     name = "local",
-    toolchain = "@echo//:echo",
+    toolchain = "@which-echo",
     toolchain_type = ":type",
 )
 
@@ -29,7 +29,7 @@ toolchain(
 
 alias(
     name = "resolved",
-    actual = "@echo//:resolved",
+    actual = "@resolved-echo",
 )
 
 toolchain_test(
@@ -41,5 +41,5 @@ toolchain_test(
 
 build_test(
     name = "entrypoint",
-    targets = ["@echo//:entrypoint"],
+    targets = ["@which-echo//:entrypoint"],
 )

toolchain/local/which/BUILD.tmpl.bazel

 load("@rules_toolchain//toolchain/symlink/path:defs.bzl", "toolchain_symlink_path")
-load("//:resolved.bzl", "resolved")
 
 package(default_visibility = ["//visibility:public"])
 
 exports_files(["entrypoint"])
 
 toolchain_symlink_path(
-    name = "{{name}}",
+    name = "{{target}}",
+    basename = "{{basename}}",
     path = "{{path}}",
     tags = ["no-remote"],
     variable = "{{variable}}",
 )
-
-resolved(
-    name = "resolved",
-    basename = "{{basename}}",
-    toolchain_type = "{{toolchain_type}}",
-)

toolchain/local/which/repository.bzl

 load("//toolchain/local/select:resolve.bzl", resolve = "value")
-load("//toolchain:resolved.bzl", _ATTRS = "ATTRS")
 
 visibility("//toolchain/...")
 
@@ -15,45 +14,28 @@ Consuming this target as a toolchain is trivial:
 toolchain(
     name = "local",
     toolchain = "@echo",
-    toolchain_type = ":type",
 )
 ```
 """
 
-ATTRS = _ATTRS | {
+ATTRS = {
     "program": attr.string(
         doc = "The name of the binary to find on `PATH`.",
     ),
     "target": attr.string(
         doc = "The name of the Bazel target to expose around the binary.",
     ),
+    "basename": attr.string(
+        doc = "The basename for the symlink, which defaults to `program`",
+    ),
     "variable": attr.string(
         doc = "The variable name for Make or the execution environment.",
     ),
-    "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`.",
-        default = "//toolchain/resolved:resolved.tmpl.bzl",
-        allow_single_file = True,
-    ),
     "build": attr.label(
         doc = "The template that is expanded into the `BUILD.bazel`.",
         default = ":BUILD.tmpl.bazel",
         allow_single_file = True,
     ),
-    "stub": attr.label_keyed_string_dict(
-        doc = "An executable to use when the local binary is not found on `PATH`.",
-        default = {
-            ":stub.bat": "windows",
-            ":stub.sh": "//conditions:default",
-        },
-        allow_files = [".bat", ".sh"],
-        allow_empty = False,
-        cfg = "exec",
-    ),
     "entrypoint": attr.label_keyed_string_dict(
         doc = "An executable entrypoint template for hermetic rulesets.",
         default = {
@@ -74,21 +56,15 @@ ATTRS = _ATTRS | {
 }
 
 def implementation(rctx):
-    program = rctx.attr.program or rctx.attr.name.rsplit("~", 1)[1]
+    program = rctx.attr.program or rctx.attr.name.rsplit("~", 1)[1].removeprefix("which-")
+    target = rctx.attr.target or rctx.attr.name.rsplit("~", 1)[1]
     basename = rctx.attr.basename or program
-    stub = resolve(rctx.attr.stub)
+    variable = rctx.attr.variable or basename.upper()
     entrypoint = resolve(rctx.attr.entrypoint)
 
     path = rctx.which(program)
     if not path:
-        if rctx.attr.mandatory:
-            fail("Cannot find `{}` on `PATH`".format(program))
-        path = rctx.path(stub)
-
-    rctx.template("resolved.bzl", rctx.attr.resolved, {
-        "{{toolchain_type}}": str(rctx.attr.toolchain_type),
-        "{{basename}}": basename,
-    }, executable = False)
+        fail("Cannot find `{}` on `PATH`".format(program))
 
     _, extension = rctx.path(entrypoint).basename.rsplit(".", 1)
     rctx.template("entrypoint.{}".format(extension), entrypoint, {
@@ -98,12 +74,11 @@ def implementation(rctx):
     rctx.symlink(rctx.attr.launcher, "entrypoint")
 
     rctx.template("BUILD.bazel", rctx.attr.build, {
-        "{{name}}": rctx.attr.target or program,
+        "{{target}}": target,
         "{{program}}": program,
         "{{basename}}": basename,
         "{{path}}": str(path.realpath),
-        "{{variable}}": rctx.attr.variable or program.upper(),
-        "{{toolchain_type}}": str(rctx.attr.toolchain_type),
+        "{{variable}}": variable,
     }, executable = False)
 
 which = repository_rule(

toolchain/local/which/stub.bat

-echo off
-
-:: Enable Batch extensions
-verify other 2>nul
-setlocal EnableExtensions
-if errorlevel 1 (
-  echo "Failed to enable extensions"
-  exit /b 120
-)
-
-:: Variables
-for /f %%i in ("%0") do set "STEM=%%~ni"
-
-:: Execute!
-(
-    echo.Usage: %0 %*
-    echo.
-    echo.This is a stub executable that is provided when the `%STEM%` binary is not found on %%PATH%%:
-    echo.
-    echo.    %PATH%
-    echo.
-    echo.It will always exit with a failure code. Either:
-    echo.
-    echo.- Install the required binary locally
-    echo.- Setup a hermetic toolchain for the binary
-) >&2
-
-exit /b 126
\ No newline at end of file

toolchain/local/which/stub.sh

-#! /bin/sh
-
-cat <<EOF >&2
-Usage: ${0} ${@}
-
-This is a stub executable that is provided when the \`${0##*/}\` binary is not found on \${PATH}:
-
-    ${PATH}
-
-It will always exit with a failure code. Either:
-
-- Install the required binary locally
-- Setup a hermetic toolchain for the binary
-EOF
-
-exit 126

toolchain/resolved/BUILD.tmpl.bazel

 load("//:resolved.bzl", "resolved")
 
 resolved(
-    name = "resolved",
+    name = "{{target}}",
     basename = "{{basename}}",
     toolchain_type = "{{toolchain_type}}",
     visibility = ["//visibility:public"],

toolchain/resolved/repository.bzl

@@ -17,6 +17,9 @@ toolchain_resolved(
 """
 
 ATTRS = _ATTRS | {
+    "target": attr.string(
+        doc = "The name of the Bazel target for the `resolved` rule.",
+    ),
     "resolved": attr.label(
         doc = "The template that is expanded into the `resolved.bzl`.",
         default = Label(":resolved.tmpl.bzl"),
@@ -33,6 +36,7 @@ def implementation(rctx):
     substitutions = {
         "{{toolchain_type}}": str(rctx.attr.toolchain_type),
         "{{basename}}": str(rctx.attr.basename),
+        "{{target}}": rctx.attr.target or rctx.attr.name.rsplit("~", 1)[1],
     }
     rctx.template("resolved.bzl", rctx.attr.resolved, substitutions, executable = False)
     rctx.template("BUILD.bazel", rctx.attr.build, substitutions, executable = False)