Register a problem matcher for MSBuild/csc errors and warnings

- Add .github/msbuild.json with two owners: one matching file-based
  diagnostics (File(line,col): error/warning CODE: msg [project]) and
  one matching engine-level errors without file/line info.
- Register the matcher in src/main.ts via the ##[add-matcher] workflow
  command, resolved relative to __dirname so it works from the ncc
  bundle in dist/.
- Add src/__tests__/msbuild-matcher.test.ts validating the matcher
  regexes against representative CS/MSB error and warning lines.
- Document the new problem matcher in README.md.
- Rebuild dist/index.js via npm run build && npm run pack.

Fixes #4

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

.github/dependabot.yml

@@ -0,0 +1,11 @@
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    groups:
+      github-actions:
+        patterns: ["*"]
+    schedule:
+      interval: "weekly"
+    cooldown:
+      default-days: 7

.github/msbuild.json

@@ -0,0 +1,30 @@
+{
+  "problemMatcher": [
+    {
+      "owner": "msbuild",
+      "pattern": [
+        {
+          "regexp": "^\\s*(?:\\d+>\\s*)?([^\\s].*?)\\((\\d+)(?:,(\\d+))?(?:,\\d+)*\\)\\s*:\\s*(error|warning)\\s+([A-Za-z]+\\d+)\\s*:\\s*(.*?)(?:\\s+\\[(.+?)\\])?\\s*$",
+          "file": 1,
+          "line": 2,
+          "column": 3,
+          "severity": 4,
+          "code": 5,
+          "message": 6,
+          "fromPath": 7
+        }
+      ]
+    },
+    {
+      "owner": "msbuild-no-location",
+      "pattern": [
+        {
+          "regexp": "^(?!.*\\().*\\b(error|warning)\\s+([A-Za-z]+\\d+)\\s*:\\s*(.*)$",
+          "severity": 1,
+          "code": 2,
+          "message": 3
+        }
+      ]
+    }
+  ]
+}

.github/workflows/test.yml

@@ -4,66 +4,76 @@ on:
     branches:
       - dev
     paths-ignore:
-      - '*.md'
+      - "*.md"
   push:
     branches:
       - dev
     paths-ignore:
-      - '*.md'
+      - "*.md"
   workflow_dispatch:
-    branches:
-      - dev
-      - arm64
-      - master
-    paths-ignore:
-      - '*.md'
-  
 
 jobs:
   build:
-    runs-on: windows-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        runner:
+          - windows-latest
+          - windows-2025-vs2026
+    runs-on: ${{ matrix.runner }}
     steps:
-    - uses: actions/checkout@v4
+      - uses: actions/checkout@d23441a48e516b6c34aea4fa41551a30e30af803 # v6.1.0
 
-    - name: Setup MSBuild (vswhere-path)
+      - name: Setup MSBuild (vswhere-path)
-      id: setup_msbuild_explicit
+        id: setup_msbuild_explicit
-      uses: ./
+        uses: ./
-      with:
+        with:
-        vswhere-path: C:\ProgramData\chocolatey\bin
+          vswhere-path: C:\ProgramData\chocolatey\bin
 
-    - name: Setup MSBuild (PATH)
+      - name: Setup MSBuild (PATH)
-      id: setup_msbuild_path
+        id: setup_msbuild_path
-      uses: ./
+        uses: ./
 
-    - name: Setup MSBuild (fallback)
+      - name: Setup MSBuild (fallback)
-      id: setup_msbuild_fallback
+        id: setup_msbuild_fallback
-      uses: ./
+        uses: ./
-      env:
+        env:
-        PATH: ''
+          PATH: ""
 
-    - name: Setup MSBuild (x64)
+      - name: Setup MSBuild (x64)
-      if: always()
+        if: runner.arch == 'X64'
-      id: setup_msbuild_path_x64
+        id: setup_msbuild_path_x64
-      uses: ./
+        uses: ./
-      with:
+        with:
-        vs-prerelease: true
+          vs-prerelease: true
-        msbuild-architecture: 'x64'
+          msbuild-architecture: "x64"
 
-    - name: Setup MSBuild (arm64)
+      - name: Setup MSBuild (arm64)
-      if: always()
+        if: runner.arch == 'ARM64'
-      id: setup_msbuild_path_arm
+        id: setup_msbuild_path_arm64
-      uses: ./
+        uses: ./
-      with:
+        with:
-        vs-prerelease: true
+          vs-prerelease: true
-        msbuild-architecture: 'arm64'
+          msbuild-architecture: "arm64"
 
-    - name: echo msbuild path
+      - name: Write MSBuild summary
-      run: |
+        if: always()
-        echo "vswhere-path: ${{ steps.setup_msbuild_explicit.outputs.msbuildPath }}"
+        shell: pwsh
-        echo "PATH: ${{ steps.setup_msbuild_path.outputs.msbuildPath }}"
+        run: |
-        echo "ARM PATH: ${{ steps.setup_msbuild_path_arm.outputs.msbuildPath }}"
+          @"
-        echo "ARM PATH: ${{ steps.setup_msbuild_path_x64.outputs.msbuildPath }}"
+          ## MSBuild setup summary
-        echo "Fallback: ${{ steps.setup_msbuild_fallback.outputs.msbuildPath }}"
 
-    - name: echo MSBuild
+          - Runner label: `${{ matrix.runner }}`
-      run: msbuild -version
+          - Runner architecture: `${{ runner.arch }}`
+
+          | Probe | msbuildPath |
+          | --- | --- |
+          | vswhere-path | ${{ steps.setup_msbuild_explicit.outputs.msbuildPath || 'N/A' }} |
+          | PATH | ${{ steps.setup_msbuild_path.outputs.msbuildPath || 'N/A' }} |
+          | Fallback | ${{ steps.setup_msbuild_fallback.outputs.msbuildPath || 'N/A' }} |
+          | x64 | ${{ steps.setup_msbuild_path_x64.outputs.msbuildPath || 'N/A' }} |
+          | arm64 | ${{ steps.setup_msbuild_path_arm64.outputs.msbuildPath || 'N/A' }} |
+          "@ | Out-File -FilePath $env:GITHUB_STEP_SUMMARY -Encoding utf8 -Append
+
+      - name: echo MSBuild
+        run: msbuild -version

README.md

@@ -2,13 +2,14 @@
 
 This action will help discover where the `MSBuild` tool is and automatically add it to the `PATH` environment variables for you so future steps in your Actions workflow can just initiate `msbuild` commands without knowing the full path.
 
+> [!IMPORTANT]
 > Please note this tool does NOT add other Visual Studio tools (like VSTest, cl, cmake, or others) to `PATH`
 
 ## Example Usage
 
 ```yml
 - name: Add msbuild to PATH
-  uses: microsoft/setup-msbuild@v1.1
+  uses: microsoft/setup-msbuild@v3
 
 - name: Build app for release
   run: msbuild src\YourProjectFile.csproj -t:rebuild -verbosity:diag -property:Configuration=Release
@@ -16,7 +17,7 @@ This action will help discover where the `MSBuild` tool is and automatically add
 
 ## Runners and included software
 
-This action is intended to be used within the GitHub Actions workflows using the model of 'runners' either hosted (provided by GitHub) or self-hosted (provided by you). The version and parameters you specify below are going to be scoped to what software actually exists on the runner image being used. For example, hosted runner images from GitHub typically do NOT have pre-release versions of Visual Studio on them so using `vs-prerelease` parameter noted below may not have intended effect when using hosted runners. The software included for GitHub-hosted runner iamges can always be found here: <https://github.com/actions/runner-images> which also includes information on when/how software on hosted images gets updated.
+This action is intended to be used within the GitHub Actions workflows using the model of 'runners' either hosted (provided by GitHub) or self-hosted (provided by you). The version and parameters you specify below are going to be scoped to what software actually exists on the runner image being used. For example, hosted runner images from GitHub typically do NOT have pre-release versions of Visual Studio on them so using `vs-prerelease` parameter noted below may not have intended effect when using hosted runners. The software included for GitHub-hosted runner images can always be found here: <https://github.com/actions/runner-images> which also includes information on when/how software on hosted images gets updated.
 
 ## Optional Parameters
 
@@ -28,7 +29,7 @@ You may have a situation where your Actions runner has multiple versions of Visu
 
 ```yml
 - name: Add msbuild to PATH
-  uses: microsoft/setup-msbuild@v1.1
+  uses: microsoft/setup-msbuild@v3
   with:
     vs-version: '[16.4,16.5)'
 ```
@@ -41,7 +42,7 @@ If you need your Actions runner to target a pre-release version of Visual Studio
 
 ```yml
 - name: Add msbuild to PATH
-  uses: microsoft/setup-msbuild@v1.1
+  uses: microsoft/setup-msbuild@v3
   with:
     vs-prerelease: true
 ```
@@ -52,7 +53,7 @@ By default the action will use the x86 architecture for MSBuild, but it is possi
 
 ```yml
 - name: Add msbuild to PATH
-  uses: microsoft/setup-msbuild@v1.1
+  uses: microsoft/setup-msbuild@v3
   with:
     msbuild-architecture: x64
 ```
@@ -63,11 +64,15 @@ This makes use of the vswhere tool which is a tool delivered by Microsoft to hel
 
 ```yml
 - name: Add msbuild to PATH
-  uses: microsoft/setup-msbuild@v1.1
+  uses: microsoft/setup-msbuild@v3
   with:
     vswhere-path: 'C:\path\to\your\tools\'
 ```
 
+## Problem matcher
+
+This action registers a [problem matcher](https://github.com/actions/toolkit/blob/main/docs/problem-matchers.md) for MSBuild/csc-style `error`/`warning` output (for example `error MSB1234:` or `error CS1234:`). Once registered, matching lines in the build log are automatically surfaced as annotations in the GitHub Actions UI and, when applicable, as pull request check annotations.
+
 ## Notes on arguments
 
 While the Action enables you to specify a `vswhere` path as well as a `vs-version`, these are more advanced options and when using GitHub-hosted runners you should not need these and is recommended you don't specify them as they are optional.  Using these require you to fully understand the runner environment, updates to the tools on the runner, and can cause failures if you are out of sync.  For GitHub-hosted runners, omitting these arguments is the preferred usage.

action.yml

@@ -23,5 +23,5 @@ outputs:
     description: "The resulting location of msbuild for your inputs"
 
 runs:
-  using: "node16"
+  using: "node24"
   main: "dist/index.js"

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "setup-msbuild",
-  "version": "1.3.2",
+  "version": "3.0.0",
   "lockfileVersion": 2,
   "requires": true,
   "packages": {
     "": {
       "name": "setup-msbuild",
-      "version": "1.3.2",
+      "version": "3.0.0",
       "license": "MIT",
       "dependencies": {
         "@actions/core": "^1.10.0",
@@ -17,7 +17,7 @@
         "@types/jest": "^24.0.23",
         "@types/node": "^12.12.25",
         "@typescript-eslint/parser": "^2.8.0",
-        "@zeit/ncc": "^0.20.5",
+        "@vercel/ncc": "^0.38.4",
         "eslint": "^5.16.0",
         "eslint-plugin-github": "^2.0.0",
         "eslint-plugin-jest": "^22.21.0",
@@ -789,12 +789,12 @@
         }
       }
     },
-    "node_modules/@zeit/ncc": {
+    "node_modules/@vercel/ncc": {
-      "version": "0.20.5",
+      "version": "0.38.4",
-      "resolved": "https://registry.npmjs.org/@zeit/ncc/-/ncc-0.20.5.tgz",
+      "resolved": "https://registry.npmjs.org/@vercel/ncc/-/ncc-0.38.4.tgz",
-      "integrity": "sha512-XU6uzwvv95DqxciQx+aOLhbyBx/13ky+RK1y88Age9Du3BlA4mMPCy13BGjayOrrumOzlq1XV3SD/BWiZENXlw==",
+      "integrity": "sha512-8LwjnlP39s08C08J5NstzriPvW1SP8Zfpp1BvC2sI35kPeZnHfxVkCwu4/+Wodgnd60UtT1n8K8zw+Mp7J9JmQ==",
-      "deprecated": "@zeit/ncc is no longer maintained. Please use @vercel/ncc instead.",
       "dev": true,
+      "license": "MIT",
       "bin": {
         "ncc": "dist/ncc/cli.js"
       }
@@ -8845,10 +8845,10 @@
         "tsutils": "^3.17.1"
       }
     },
-    "@zeit/ncc": {
+    "@vercel/ncc": {
-      "version": "0.20.5",
+      "version": "0.38.4",
-      "resolved": "https://registry.npmjs.org/@zeit/ncc/-/ncc-0.20.5.tgz",
+      "resolved": "https://registry.npmjs.org/@vercel/ncc/-/ncc-0.38.4.tgz",
-      "integrity": "sha512-XU6uzwvv95DqxciQx+aOLhbyBx/13ky+RK1y88Age9Du3BlA4mMPCy13BGjayOrrumOzlq1XV3SD/BWiZENXlw==",
+      "integrity": "sha512-8LwjnlP39s08C08J5NstzriPvW1SP8Zfpp1BvC2sI35kPeZnHfxVkCwu4/+Wodgnd60UtT1n8K8zw+Mp7J9JmQ==",
       "dev": true
     },
     "abab": {

package.json

@@ -1,6 +1,6 @@
 {
   "name": "setup-msbuild",
-  "version": "1.3.2",
+  "version": "3.0.0",
   "private": true,
   "description": "Helps set up specific MSBuild tool into PATH for later usage.",
   "main": "lib/main.js",
@@ -9,7 +9,7 @@
     "format": "prettier --write **/*.ts",
     "format-check": "prettier --check **/*.ts",
     "lint": "eslint src/**/*.ts",
-    "pack": "ncc build",
+    "pack": "ncc build lib/main.js -o dist",
     "test": "jest",
     "all": "npm run build && npm run format && npm run lint && npm run pack"
   },
@@ -36,7 +36,7 @@
     "@types/jest": "^24.0.23",
     "@types/node": "^12.12.25",
     "@typescript-eslint/parser": "^2.8.0",
-    "@zeit/ncc": "^0.20.5",
+    "@vercel/ncc": "^0.38.4",
     "eslint": "^5.16.0",
     "eslint-plugin-github": "^2.0.0",
     "eslint-plugin-jest": "^22.21.0",

src/__tests__/msbuild-matcher.test.ts

@@ -0,0 +1,101 @@
+import * as fs from 'fs'
+import * as path from 'path'
+
+interface ProblemMatcherPattern {
+  regexp: string
+  file?: number
+  line?: number
+  column?: number
+  severity?: number
+  code?: number
+  message?: number
+  fromPath?: number
+}
+
+interface ProblemMatcherOwner {
+  owner: string
+  pattern: ProblemMatcherPattern[]
+}
+
+interface ProblemMatcherFile {
+  problemMatcher: ProblemMatcherOwner[]
+}
+
+const matcherPath = path.join(__dirname, '..', '..', '.github', 'msbuild.json')
+const matcherFile: ProblemMatcherFile = JSON.parse(
+  fs.readFileSync(matcherPath, 'utf8')
+)
+
+function findOwner(owner: string): ProblemMatcherOwner {
+  const found = matcherFile.problemMatcher.find(m => m.owner === owner)
+  if (!found) {
+    throw new Error(`No matcher owner named ${owner} found`)
+  }
+  return found
+}
+
+describe('msbuild problem matcher', () => {
+  it('is valid JSON with the expected owners', () => {
+    expect(matcherFile.problemMatcher.map(m => m.owner)).toEqual([
+      'msbuild',
+      'msbuild-no-location'
+    ])
+  })
+
+  describe('msbuild owner (file-based diagnostics)', () => {
+    const regexp = new RegExp(findOwner('msbuild').pattern[0].regexp)
+
+    it('matches a csc-style error with file, line, column and project path', () => {
+      const line =
+        'Program.cs(10,5): error CS1002: ; expected [C:\\proj\\proj.csproj]'
+      const match = regexp.exec(line)
+      expect(match).not.toBeNull()
+      expect(match?.[1]).toBe('Program.cs')
+      expect(match?.[2]).toBe('10')
+      expect(match?.[3]).toBe('5')
+      expect(match?.[4]).toBe('error')
+      expect(match?.[5]).toBe('CS1002')
+      expect(match?.[6]).toBe('; expected')
+      expect(match?.[7]).toBe('C:\\proj\\proj.csproj')
+    })
+
+    it('matches an MSB-coded warning with file and line only', () => {
+      const line =
+        'C:\\proj\\proj.csproj(15,1): warning MSB3277: Found conflicts [C:\\proj\\proj.csproj]'
+      const match = regexp.exec(line)
+      expect(match).not.toBeNull()
+      expect(match?.[4]).toBe('warning')
+      expect(match?.[5]).toBe('MSB3277')
+    })
+
+    it('matches a diagnostic without a trailing project path', () => {
+      const line = 'Program.cs(3,1): error CS0246: The type or namespace name could not be found'
+      const match = regexp.exec(line)
+      expect(match).not.toBeNull()
+      expect(match?.[5]).toBe('CS0246')
+      expect(match?.[6]).toBe(
+        'The type or namespace name could not be found'
+      )
+      expect(match?.[7]).toBeUndefined()
+    })
+  })
+
+  describe('msbuild-no-location owner (engine-level diagnostics)', () => {
+    const regexp = new RegExp(findOwner('msbuild-no-location').pattern[0].regexp)
+
+    it('matches an MSBuild engine error with no file/line info', () => {
+      const line = 'MSBUILD : error MSB1009: Project file does not exist.'
+      const match = regexp.exec(line)
+      expect(match).not.toBeNull()
+      expect(match?.[1]).toBe('error')
+      expect(match?.[2]).toBe('MSB1009')
+      expect(match?.[3]).toBe('Project file does not exist.')
+    })
+
+    it('does not match lines already covered by the file-based owner', () => {
+      const line =
+        'Program.cs(10,5): error CS1002: ; expected [C:\\proj\\proj.csproj]'
+      expect(regexp.test(line)).toBe(false)
+    })
+  })
+})

src/main.ts

@@ -23,8 +23,17 @@ if (VS_VERSION !== 'latest') {
 
 core.debug(`Execution arguments: ${VSWHERE_EXEC}`)
 
+function registerProblemMatcher(): void {
+  const matcherPath = path.join(__dirname, '..', '.github', 'msbuild.json')
+  core.info(`##[add-matcher]${matcherPath}`)
+}
+
 async function run(): Promise<void> {
   try {
+    // register the problem matcher so MSBuild/csc errors and warnings are
+    // annotated in the workflow log and any related pull request
+    registerProblemMatcher()
+
     // exit if non Windows runner
     if (IS_WINDOWS === false) {
       core.setFailed('setup-msbuild can only be run on Windows runners')