Use tc.find() with the effective tool cache path

* So it finds already-download prebuilt Ruby in the GH-hosted tool cache path
  on self-hosted, where $RUNNER_TOOL_CACHE is often different than on GH-hosted.
* See #475.
* This relies on tc.find() looking up the env var every time:
  https://github.com/actions/toolkit/blob/1f4b3fac06/packages/tool-cache/src/tool-cache.ts#L522

common.js

@@ -5,6 +5,7 @@ const util = require('util')
 const stream = require('stream')
 const crypto = require('crypto')
 const core = require('@actions/core')
+const tc = require('@actions/tool-cache')
 const { performance } = require('perf_hooks')
 const linuxOSInfo = require('linux-os-info')
 import macosRelease from 'macos-release'
@@ -166,17 +167,14 @@ const GitHubHostedPlatforms = [
   'windows-2022-x64',
 ]
 
-// Actually a self-hosted runner for which either
+// Actually a self-hosted runner for which  the OS and OS version does not correspond to a GitHub-hosted runner image,
-// * the OS and OS version does not correspond to a GitHub-hosted runner image,
-// * or the hosted tool cache is different from the default tool cache path
 export function isSelfHostedRunner() {
   if (inputs.selfHosted === undefined) {
     throw new Error('inputs.selfHosted should have been already set')
   }
 
   return inputs.selfHosted === 'true' ||
-    !GitHubHostedPlatforms.includes(getOSNameVersionArch()) ||
+    !GitHubHostedPlatforms.includes(getOSNameVersionArch())
-    getRunnerToolCache() !== getDefaultToolCachePath()
 }
 
 export function selfHostedRunnerReason() {
@@ -184,8 +182,6 @@ export function selfHostedRunnerReason() {
     return 'the self-hosted input was set'
   } else if (!GitHubHostedPlatforms.includes(getOSNameVersionArch())) {
     return 'the platform does not match a GitHub-hosted runner image (or that image is deprecated and no longer supported)'
-  } else if (getRunnerToolCache() !== getDefaultToolCachePath()) {
-    return 'the $RUNNER_TOOL_CACHE is different than the default tool cache path (they must be the same to reuse prebuilt Ruby binaries)'
   } else {
     return 'unknown reason'
   }
@@ -237,6 +233,16 @@ export function shouldUseToolCache(engine, version) {
   return (engine === 'ruby' && !isHeadVersion(version)) || isSelfHostedRunner()
 }
 
+export function getToolCachePath() {
+  if (isSelfHostedRunner()) {
+    return getRunnerToolCache()
+  } else {
+    // Rubies prebuilt by this action embed this path rather than using $RUNNER_TOOL_CACHE
+    // so use that path is not isSelfHostedRunner()
+    return getDefaultToolCachePath()
+  }
+}
+
 export function getRunnerToolCache() {
   const runnerToolCache = process.env['RUNNER_TOOL_CACHE']
   if (!runnerToolCache) {
@@ -245,8 +251,7 @@ export function getRunnerToolCache() {
   return runnerToolCache
 }
 
-// Rubies prebuilt by this action embed this path rather than using $RUNNER_TOOL_CACHE,
+// Rubies prebuilt by this action embed this path rather than using $RUNNER_TOOL_CACHE
-// so they can only be used if the two paths are the same
 function getDefaultToolCachePath() {
   const platform = getVirtualEnvironmentName()
   if (platform.startsWith('ubuntu-')) {
@@ -260,15 +265,29 @@ function getDefaultToolCachePath() {
   }
 }
 
-export function getToolCacheRubyPrefix(platform, engine, version) {
+// tc.find() but using RUNNER_TOOL_CACHE=getToolCachePath()
-  const toolCache = getRunnerToolCache()
+export function toolCacheFind(engine, version) {
-  const name = {
+  const originalToolCache = getToolCachePath()
+  process.env['RUNNER_TOOL_CACHE'] = getToolCachePath()
+  try {
+    return tc.find(engineToToolCacheName(engine), version)
+  } finally {
+    process.env['RUNNER_TOOL_CACHE'] = originalToolCache
+  }
+}
+
+function engineToToolCacheName(engine) {
+  return {
     ruby: 'Ruby',
     jruby: 'JRuby',
     truffleruby: 'TruffleRuby',
     "truffleruby+graalvm": 'TruffleRubyGraalVM'
   }[engine]
-  return path.join(toolCache, name, version, os.arch())
+}
+
+export function getToolCacheRubyPrefix(platform, engine, version) {
+  const toolCache = getToolCachePath()
+  return path.join(toolCache, engineToToolCacheName(engine), version, os.arch())
 }
 
 export function toolCacheCompleteFile(toolCacheRubyPrefix) {

dist/index.js

@@ -292,6 +292,7 @@ __nccwpck_require__.d(__webpack_exports__, {
   "floatVersion": () => (/* binding */ floatVersion),
   "getOSNameVersionArch": () => (/* binding */ getOSNameVersionArch),
   "getRunnerToolCache": () => (/* binding */ getRunnerToolCache),
+  "getToolCachePath": () => (/* binding */ getToolCachePath),
   "getToolCacheRubyPrefix": () => (/* binding */ getToolCacheRubyPrefix),
   "getVirtualEnvironmentName": () => (/* binding */ getVirtualEnvironmentName),
   "hasBundlerDefaultGem": () => (/* binding */ hasBundlerDefaultGem),
@@ -311,6 +312,7 @@ __nccwpck_require__.d(__webpack_exports__, {
   "targetRubyVersion": () => (/* binding */ targetRubyVersion),
   "time": () => (/* binding */ time),
   "toolCacheCompleteFile": () => (/* binding */ toolCacheCompleteFile),
+  "toolCacheFind": () => (/* binding */ toolCacheFind),
   "win2nix": () => (/* binding */ win2nix),
   "windows": () => (/* binding */ windows)
 });
@@ -360,6 +362,7 @@ const util = __nccwpck_require__(3837)
 const stream = __nccwpck_require__(2781)
 const common_crypto = __nccwpck_require__(6113)
 const core = __nccwpck_require__(2186)
+const tc = __nccwpck_require__(7784)
 const { performance } = __nccwpck_require__(4074)
 const linuxOSInfo = __nccwpck_require__(8487)
 ;
@@ -521,17 +524,14 @@ const GitHubHostedPlatforms = [
   'windows-2022-x64',
 ]
 
-// Actually a self-hosted runner for which either
+// Actually a self-hosted runner for which  the OS and OS version does not correspond to a GitHub-hosted runner image,
-// * the OS and OS version does not correspond to a GitHub-hosted runner image,
-// * or the hosted tool cache is different from the default tool cache path
 function isSelfHostedRunner() {
   if (inputs.selfHosted === undefined) {
     throw new Error('inputs.selfHosted should have been already set')
   }
 
   return inputs.selfHosted === 'true' ||
-    !GitHubHostedPlatforms.includes(getOSNameVersionArch()) ||
+    !GitHubHostedPlatforms.includes(getOSNameVersionArch())
-    getRunnerToolCache() !== getDefaultToolCachePath()
 }
 
 function selfHostedRunnerReason() {
@@ -539,8 +539,6 @@ function selfHostedRunnerReason() {
     return 'the self-hosted input was set'
   } else if (!GitHubHostedPlatforms.includes(getOSNameVersionArch())) {
     return 'the platform does not match a GitHub-hosted runner image (or that image is deprecated and no longer supported)'
-  } else if (getRunnerToolCache() !== getDefaultToolCachePath()) {
-    return 'the $RUNNER_TOOL_CACHE is different than the default tool cache path (they must be the same to reuse prebuilt Ruby binaries)'
   } else {
     return 'unknown reason'
   }
@@ -592,6 +590,16 @@ function shouldUseToolCache(engine, version) {
   return (engine === 'ruby' && !isHeadVersion(version)) || isSelfHostedRunner()
 }
 
+function getToolCachePath() {
+  if (isSelfHostedRunner()) {
+    return getRunnerToolCache()
+  } else {
+    // Rubies prebuilt by this action embed this path rather than using $RUNNER_TOOL_CACHE
+    // so use that path is not isSelfHostedRunner()
+    return getDefaultToolCachePath()
+  }
+}
+
 function getRunnerToolCache() {
   const runnerToolCache = process.env['RUNNER_TOOL_CACHE']
   if (!runnerToolCache) {
@@ -600,8 +608,7 @@ function getRunnerToolCache() {
   return runnerToolCache
 }
 
-// Rubies prebuilt by this action embed this path rather than using $RUNNER_TOOL_CACHE,
+// Rubies prebuilt by this action embed this path rather than using $RUNNER_TOOL_CACHE
-// so they can only be used if the two paths are the same
 function getDefaultToolCachePath() {
   const platform = getVirtualEnvironmentName()
   if (platform.startsWith('ubuntu-')) {
@@ -615,15 +622,29 @@ function getDefaultToolCachePath() {
   }
 }
 
-function getToolCacheRubyPrefix(platform, engine, version) {
+// tc.find() but using RUNNER_TOOL_CACHE=getToolCachePath()
-  const toolCache = getRunnerToolCache()
+function toolCacheFind(engine, version) {
-  const name = {
+  const originalToolCache = getToolCachePath()
+  process.env['RUNNER_TOOL_CACHE'] = getToolCachePath()
+  try {
+    return tc.find(engineToToolCacheName(engine), version)
+  } finally {
+    process.env['RUNNER_TOOL_CACHE'] = originalToolCache
+  }
+}
+
+function engineToToolCacheName(engine) {
+  return {
     ruby: 'Ruby',
     jruby: 'JRuby',
     truffleruby: 'TruffleRuby',
     "truffleruby+graalvm": 'TruffleRubyGraalVM'
   }[engine]
-  return path.join(toolCache, name, version, os.arch())
+}
+
+function getToolCacheRubyPrefix(platform, engine, version) {
+  const toolCache = getToolCachePath()
+  return path.join(toolCache, engineToToolCacheName(engine), version, os.arch())
 }
 
 function toolCacheCompleteFile(toolCacheRubyPrefix) {
@@ -68275,7 +68296,7 @@ function getAvailableVersions(platform, engine) {
 async function install(platform, engine, version) {
   let rubyPrefix, inToolCache
   if (common.shouldUseToolCache(engine, version)) {
-    inToolCache = tc.find('Ruby', version)
+    inToolCache = common.toolCacheFind(engine, version)
     if (inToolCache) {
       rubyPrefix = inToolCache
     } else {
@@ -68283,7 +68304,7 @@ async function install(platform, engine, version) {
       if (common.isSelfHostedRunner()) {
         const rubyBuildDefinition = engine === 'ruby' ? version : `${engine}-${version}`
         core.error(
-          `The current runner (${common.getOSNameVersionArch()}, RUNNER_TOOL_CACHE=${common.getRunnerToolCache()}) was detected as self-hosted because ${common.selfHostedRunnerReason()}.\n` +
+          `The current runner (${common.getOSNameVersionArch()}) was detected as self-hosted because ${common.selfHostedRunnerReason()}.\n` +
           `In such a case, you should install Ruby in the $RUNNER_TOOL_CACHE yourself, for example using https://github.com/rbenv/ruby-build\n` +
           `You can take inspiration from this workflow for more details: https://github.com/ruby/ruby-builder/blob/master/.github/workflows/build.yml\n` +
           `$ ruby-build ${rubyBuildDefinition} ${toolCacheRubyPrefix}\n` +
@@ -68489,7 +68510,7 @@ async function install(platform, engine, version) {
 
   let rubyPrefix, inToolCache
   if (common.shouldUseToolCache(engine, version)) {
-    inToolCache = tc.find('Ruby', version)
+    inToolCache = common.toolCacheFind(engine, version)
     if (inToolCache) {
       rubyPrefix = inToolCache
     } else {

ruby-builder.js

@@ -20,7 +20,7 @@ export function getAvailableVersions(platform, engine) {
 export async function install(platform, engine, version) {
   let rubyPrefix, inToolCache
   if (common.shouldUseToolCache(engine, version)) {
-    inToolCache = tc.find('Ruby', version)
+    inToolCache = common.toolCacheFind(engine, version)
     if (inToolCache) {
       rubyPrefix = inToolCache
     } else {
@@ -28,7 +28,7 @@ export async function install(platform, engine, version) {
       if (common.isSelfHostedRunner()) {
         const rubyBuildDefinition = engine === 'ruby' ? version : `${engine}-${version}`
         core.error(
-          `The current runner (${common.getOSNameVersionArch()}, RUNNER_TOOL_CACHE=${common.getRunnerToolCache()}) was detected as self-hosted because ${common.selfHostedRunnerReason()}.\n` +
+          `The current runner (${common.getOSNameVersionArch()}) was detected as self-hosted because ${common.selfHostedRunnerReason()}.\n` +
           `In such a case, you should install Ruby in the $RUNNER_TOOL_CACHE yourself, for example using https://github.com/rbenv/ruby-build\n` +
           `You can take inspiration from this workflow for more details: https://github.com/ruby/ruby-builder/blob/master/.github/workflows/build.yml\n` +
           `$ ruby-build ${rubyBuildDefinition} ${toolCacheRubyPrefix}\n` +

windows.js

@@ -49,7 +49,7 @@ export async function install(platform, engine, version) {
 
   let rubyPrefix, inToolCache
   if (common.shouldUseToolCache(engine, version)) {
-    inToolCache = tc.find('Ruby', version)
+    inToolCache = common.toolCacheFind(engine, version)
     if (inToolCache) {
       rubyPrefix = inToolCache
     } else {