feat: set apt alternatives when llvm/gcc is installed

src/gcc/gcc.ts

@@ -1,6 +1,6 @@
 import { addPath, addEnv } from "../utils/env/addEnv"
 import { existsSync } from "fs"
-import { setupAptPack } from "../utils/setup/setupAptPack"
+import { setupAptPack, updateAptAlternatives } from "../utils/setup/setupAptPack"
 import { setupBrewPack } from "../utils/setup/setupBrewPack"
 import { setupChocoPack } from "../utils/setup/setupChocoPack"
 import semverMajor from "semver/functions/major"
@@ -96,9 +96,19 @@ async function activateGcc(version: string, binDir: string) {
     if (majorVersion >= 5) {
       addEnv("CC", `${binDir}/gcc-${majorVersion}`)
       addEnv("CXX", `${binDir}/g++-${majorVersion}`)
+
+      if (process.platform === "linux") {
+        await updateAptAlternatives("cc", `${binDir}/gcc-${majorVersion}`)
+        await updateAptAlternatives("cxx", `${binDir}/g++-${majorVersion}`)
+      }
     } else {
       addEnv("CC", `${binDir}/gcc-${version}`)
       addEnv("CXX", `${binDir}/g++-${version}`)
+
+      if (process.platform === "linux") {
+        await updateAptAlternatives("cc", `${binDir}/gcc-${version}`)
+        await updateAptAlternatives("cxx", `${binDir}/g++-${version}`)
+      }
     }
   }
 

src/llvm/llvm.ts

@@ -9,7 +9,7 @@ import { setupMacOSSDK } from "../macos-sdk/macos-sdk"
 import { addBinExtension } from "../utils/extension/extension"
 import { addEnv } from "../utils/env/addEnv"
 import { info, setOutput } from "@actions/core"
-import { setupAptPack } from "../utils/setup/setupAptPack"
+import { setupAptPack, updateAptAlternatives } from "../utils/setup/setupAptPack"
 import { warning } from "../utils/io/io"
 import { existsSync } from "fs"
 import { isGitHubCI } from "../utils/env/isci"
@@ -307,6 +307,16 @@ export async function activateLLVM(directory: string, versionGiven: string) {
 
   await setupMacOSSDK()
 
+  if (process.platform === "linux") {
+    await updateAptAlternatives("cc", `${directory}/bin/clang`)
+    await updateAptAlternatives("cxx", `${directory}/bin/clang++`)
+    await updateAptAlternatives("clang", `${directory}/bin/clang`)
+    await updateAptAlternatives("clang++", `${directory}/bin/clang++`)
+    await updateAptAlternatives("lld", `${directory}/bin/lld`)
+    await updateAptAlternatives("ld.lld", `${directory}/bin/ld.lld`)
+    await updateAptAlternatives("llvm-ar", `${directory}/bin/llvm-ar`)
+  }
+
   if (isGitHubCI()) {
     addLLVMLoggingMatcher()
   }

src/utils/env/addEnv.ts

@@ -45,7 +45,7 @@ export function addPath(path: string) {
   }
 }
 
-const cpprc_path = untildify(".cpprc")
+export const cpprc_path = untildify(".cpprc")
 
 function addEnvSystem(name: string, valGiven: string | undefined) {
   const val = valGiven ?? ""
@@ -96,7 +96,7 @@ function addPathSystem(path: string) {
 let setupCppInProfile_called = false
 
 /// handles adding conditions to source .cpprc file from .bashrc and .profile
-function setupCppInProfile() {
+export function setupCppInProfile() {
   if (setupCppInProfile_called) {
     return
   }

src/utils/setup/setupAptPack.ts

@@ -3,6 +3,9 @@ import { InstallationInfo } from "./setupBin"
 import { execSudo } from "../exec/sudo"
 import { info } from "@actions/core"
 import { warning } from "../io/io"
+import { isGitHubCI } from "../env/isci"
+import { cpprc_path, setupCppInProfile } from "../env/addEnv"
+import { appendFileSync } from "fs"
 
 let didUpdate: boolean = false
 let didInit: boolean = false
@@ -68,3 +71,15 @@ export async function setupAptPack(
 
   return { binDir: "/usr/bin/" }
 }
+
+export function updateAptAlternatives(name: string, path: string) {
+  if (isGitHubCI()) {
+    return execSudo("update-alternatives", ["--install", `/usr/bin/${name}`, name, path, "10"])
+  } else {
+    setupCppInProfile()
+    return appendFileSync(
+      cpprc_path,
+      `\nif [ $UID -eq 0 ]; then update-alternatives --install /usr/bin/${name} ${name} ${path} 10; fi\n`
+    )
+  }
+}