[Bug]: VSCode problem matcher does not work in latest version

[kittybwained]

Environment

• OS and Version: Windows 11 IoT Enterprise LTSC 24H2 26100.7171
• IDE Version: Visual Studio Code 1.108.1
• Ada & SPARK Extension Version: v2026.1.202601121

Bug Summary and Reproducer

Bug Summary: Error highlighting from Check current file and other build tasks no longer works reliably

Steps to reproduce: Run Ada: check current file on semantically incorrect code

Expected behavior: For errors to be highlighted as they are with extension version 2026.0.202510141

Configuration and Logs

tasks.json:

{
	"version": "2.0.0",
	"tasks": [
		{
			"type": "ada",
			"command": "gprbuild",
			"args": [
				"-q",
				"-f",
				"-c",
				"-u",
				"-gnatc",
				"${command:ada.gprProjectArgs}",
				"${fileBasename}",
				"'-cargs:ada'",
				"-gnatef"
			],
			"problemMatcher": [
				"$ada-error",
				"$ada-warning",
				"$ada-info"
			],
			"label": "adacheckbg",
			"presentation": {
				"echo": true,
				"reveal": "never",
				"focus": false,
				"panel": "shared",
				"showReuseMessage": false,
				"clear": true
			}
		}
	]
}

workspace ada extension settings:

"ada.projectFile": "tdfa.gpr",
"ada.defaultCharset": "UTF-8",
"ada.useCompletionSnippets": true,
"ada.adaFileDiagnostics": true,
"ada.alireDiagnostics": true,
"ada.gprFileDiagnostics": true,
"ada.projectDiagnostics": true,
"ada.sourceInfoDiagnostics": true,

show extension output:

2026-01-19 07:53:17.638 [Ada Extension] INFO     Setting log level to: debug 
2026-01-19 07:53:17.639 [Ada Extension] INFO     Starting Ada extension 
2026-01-19 07:53:17.639 [Ada Extension] DEBUG    Asserted compatibility with runtime environment: x64, win32 
2026-01-19 07:53:17.640 [Ada Extension] DEBUG    No custom environment variables set in terminal.integrated.env.windows 
2026-01-19 07:53:17.640 [Ada Extension] INFO     Using ALS at: c:\Users\kohuept\.vscode\extensions\adacore.ada-2026.1.202601121-win32-x64\x64\win32\ada_language_server.exe 
2026-01-19 07:53:17.648 [Ada Extension] INFO     Using ALS at: c:\Users\kohuept\.vscode\extensions\adacore.ada-2026.1.202601121-win32-x64\x64\win32\ada_language_server.exe 
2026-01-19 07:53:17.654 [Ada Extension] INFO     didChangeConfiguration event received 
2026-01-19 07:53:17.655 [Ada Extension] INFO     didChangeConfiguration event received 
2026-01-19 07:53:17.715 [Ada Extension] INFO     didChangeConfiguration event received 
2026-01-19 07:53:17.797 [Ada Extension] INFO     didChangeConfiguration event received 
2026-01-19 07:53:17.818 [Ada Extension] INFO     didChangeConfiguration event received 
2026-01-19 07:53:17.845 [Ada Extension] INFO     Loading e3-testsuite: {"uri":{"$mid":1,"path":"/c:/Users/kohuept/src/TDFA/testsuite.py","scheme":"file"},"python":"python"} 
2026-01-19 07:53:17.845 [Ada Extension] INFO     c:\Users\kohuept\src\TDFA\testsuite.py doesn't exist, doing nothing. 
2026-01-19 07:53:17.845 [Ada Extension] INFO     Finished starting Ada extension 
2026-01-19 07:53:18.084 [Ada Extension] INFO     didChangeConfiguration event received 
2026-01-19 07:53:18.181 [Ada Extension] INFO     didChangeConfiguration event received 
2026-01-19 07:53:19.340 [Ada Extension] INFO     Got Project.Compiler.Driver ("ada") = c:\users\kohuept\documents\ada tools\gnat-x86_64-windows64-16.0.0-custom\bin\gcc 
2026-01-19 07:53:19.340 [Ada Extension] INFO     Computed target prefix:  
2026-01-19 07:53:19.420 [Ada Extension] INFO     Got Project.Compiler.Driver ("ada") = c:\users\kohuept\documents\ada tools\gnat-x86_64-windows64-16.0.0-custom\bin\gcc 
2026-01-19 07:53:19.420 [Ada Extension] INFO     Computed target prefix:  
2026-01-19 07:53:19.503 [Ada Extension] INFO     didChangeConfiguration event received 
2026-01-19 07:53:21.898 [Ada Extension] DEBUG    Retrieved saved SPARK picker state: undefined 
2026-01-19 07:53:21.899 [Ada Extension] DEBUG    Retrieved saved SPARK picker state: undefined 
2026-01-19 07:53:21.900 [Ada Extension] DEBUG    Retrieved saved SPARK picker state: undefined 
2026-01-19 07:53:21.901 [Ada Extension] DEBUG    Retrieved saved SPARK picker state: undefined 
2026-01-19 07:53:21.902 [Ada Extension] DEBUG    Retrieved saved SPARK picker state: undefined 
2026-01-19 07:53:21.902 [Ada Extension] DEBUG    Retrieved saved SPARK picker state: undefined 
2026-01-19 07:53:21.904 [Ada Extension] DEBUG    Retrieved saved SPARK picker state: undefined 
2026-01-19 07:53:21.905 [Ada Extension] DEBUG    Retrieved saved SPARK picker state: undefined 
2026-01-19 07:53:26.858 [Ada Extension] DEBUG    Retrieved saved SPARK picker state: undefined 
2026-01-19 07:53:26.858 [Ada Extension] DEBUG    Retrieved saved SPARK picker state: undefined 
2026-01-19 07:53:26.859 [Ada Extension] DEBUG    Retrieved saved SPARK picker state: undefined 
2026-01-19 07:53:26.864 [Ada Extension] DEBUG    Retrieved saved SPARK picker state: undefined 
2026-01-19 07:53:26.864 [Ada Extension] DEBUG    Retrieved saved SPARK picker state: undefined 
2026-01-19 07:53:26.865 [Ada Extension] DEBUG    Retrieved saved SPARK picker state: undefined 
2026-01-19 07:53:26.870 [Ada Extension] DEBUG    Retrieved saved SPARK picker state: undefined 
2026-01-19 07:53:26.871 [Ada Extension] DEBUG    Retrieved saved SPARK picker state: undefined 

language server log:

[ALS.MAIN] ALS version: 27.0w (20260112)
[ALS.MAIN] Initializing server ...
[ALS.MAIN] GPR PATH: 
[ALS.MAIN] PATH: C:\Program Files\FireDaemon OpenSSL 3\bin\;C:\Program Files\Eclipse Adoptium\jdk-21.0.5.11-hotspot\bin;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\WINDOWS\System32\WindowsPowerShell\v1.0\;C:\WINDOWS\System32\OpenSSH\;C:\Program Files (x86)\NVIDIA Corporation\PhysX\Common;C:\Program Files\IBM\Trace Facility;C:\ProgramData\chocolatey\bin;C:\Program Files\gs\gs10.04.0\bin;C:\Program Files\rexx.org\THE;C:\GNATSTUDIO\bin;C:\Users\kohuept\AppData\Local\Programs\Python\Launcher\;C:\Users\kohuept\AppData\Local\Microsoft\WindowsApps;C:\Users\kohuept\AppData\Local\Programs\Microsoft VS Code\bin;C:\Users\kohuept\.dotnet\tools;C:\Users\kohuept\AppData\Local\Microsoft\WinGet\Packages\Madsen.VBinDiff_Microsoft.Winget.Source_8wekyb3d8bbwe;C:\Program Files (x86)\Dr. Memory\bin\;C:\Users\kohuept\AppData\Local\Microsoft\WinGet\Packages\AlDanial.Cloc_Microsoft.Winget.Source_8wekyb3d8bbwe;C:\Users\kohuept\bin;C:\Program Files\gs\gs10.04.0\lib;C:\Users\kohuept\Downloads\Release-24.08.0-0\poppler-24.08.0\Library\bin;C:\Program Files (x86)\SPFLite3;C:\Program Files\Git\cmd;C:\Program Files (x86)\Windows Kits\10\Windows Performance Toolkit\;C:\Program Files (x86)\IBM\Personal Communications\;C:\Program Files (x86)\IBM\Trace Facility\;C:\Program Files (x86)\SoftDevLabs\AWSBrowse;C:\Program Files (x86)\SoftDevLabs\FishLib;C:\Program Files\PuTTY\;C:\Program Files\dotnet\;C:\Program Files\Sunshine;C:\Program Files\Sunshine\tools;C:\Program Files\rexx.org\Regina;C:\Program Files\oorexx;C:\GNATSTUDIO\bin;C:\Users\kohuept\AppData\Local\Programs\Python\Python312\Scripts\;C:\Users\kohuept\AppData\Local\Programs\Python\Python312\;C:\Users\kohuept\AppData\Local\Microsoft\WindowsApps;C:\Users\kohuept\AppData\Local\Programs\Microsoft VS Code\bin;C:\Users\kohuept\AppData\Local\Microsoft\WinGet\Packages\Madsen.VBinDiff_Microsoft.Winget.Source_8wekyb3d8bbwe;C:\Program Files (x86)\Dr. Memory\bin\;C:\Users\kohuept\AppData\Local\Microsoft\WinGet\Packages\AlDanial.Cloc_Microsoft.Winget.Source_8wekyb3d8bbwe;C:\Users\kohuept\bin;C:\Program Files\gs\gs10.04.0\lib;C:\Program Files\gs\gs10.04.0\bin;C:\Users\kohuept\Downloads\Release-24.08.0-0\poppler-24.08.0\Library\bin;C:\Users\kohuept\AppData\Local\Programs\MiKTeX\miktex\bin\x64\;C:\Users\kohuept\AppData\Local\Programs\MiKTeX\miktex\bin\x64;C:\Program Files\LLVM\bin;C:\Users\kohuept\src\hercules-vs2022\sdl-hyperion\msvc.AMD64.bin;C:\Users\kohuept\Documents\Ada Tools\gnatprove-x86_64-windows64-16.0.0-20251223\bin;C:\Users\kohuept\Documents\Ada Tools\gnat-x86_64-windows64-16.0.0-custom\bin;C:\Users\kohuept\Documents\Ada Tools\gprbuild-x86_64-windows64-25.0.0-1\bin;C:\Users\kohuept\.dotnet\tools;C:\Users\kohuept\AppData\Local\GitHubDesktop\bin;C:\Program Files\Graphviz\bin;C:\Users\kohuept\Downloads\mpv-x86_64-v3-20251202-git-72dbcf1;C:\Users\kohuept\Documents\Ada Tools\gnat-x86_64-windows64-16.0.0-custom\lib\gcc\x86_64-w64-mingw32\16.0.0\adalib;
[ALS.MAIN] Trying config file: C:\Users\kohuept\.config\als\config.json
[ALS.MAIN] C:\Users\kohuept\.config\als\config.json doesn't exist
[ALS.MAIN] Trying config file: C:\Users\kohuept\src\TDFA\.als.json
[ALS.MAIN] C:\Users\kohuept\src\TDFA\.als.json doesn't exist
[ALS.MAIN] Ada version used for predefined completion: ADA_2020
[ALS.MAIN] Processing initializationOptions from initialize request
[ALS.PROJECT] Found ada.projectFile = tdfa.gpr
[ALS.PROJECT] Loading project: tdfa.gpr
[ALS.PROJECT] Loading project with GPR2
[ALS.PROJECT] GPR2 messages after load:
   [ALS.PROJECT] No GPR2 messages
[ALS.PROJECT] Updating project sources
[ALS.PROJECT] GPR2 messages after updating sources:
   [ALS.PROJECT] No GPR2 messages
[ALS.PROJECT] Prepend Context Id: file:///C%3A/Users/kohuept/src/TDFA/tdfa.gpr
[ALS.PROJECT] Project status after loading: 
_ALS.PROJECT_ (PROJECT_TYPE => CONFIGURED_PROJECT,
_ALS.PROJECT_  STATUS => VALID_PROJECT,
_ALS.PROJECT_  PROJECT_FILE => {GNATCOLL.VFS.VIRTUAL_FILE object},
_ALS.PROJECT_  MISSING_ADA_RUNTIME => FALSE,
_ALS.PROJECT_  GPR2_MESSAGES => {GPR2.LOG.OBJECT object},
_ALS.PROJECT_  ALIRE_MESSAGES => {VSS.STRING_VECTORS.VIRTUAL_STRING_VECTOR object})
[ALS.MAIN] Creating fallback context
[ALS.MAIN] In Message_Handler Text_Document_Did_Open URI:
[ALS.MAIN] file:///c%3A/Users/kohuept/src/TDFA/src/main.adb
[ALS.MAIN] Out Message_Handler Text_Document_Did_Open
[ALS.MAIN] Getting completions, Pos = ( 2552,  32) Node = <Id "Interference_Matrixx" main.adb:2552:12-2552:32>
[ALS.MAIN] Number of filtered completions :  0

Other VS Code Extensions

Disabling all other extensions did not change anything.

Additional context

Downgrading to the previous version seems to fix the issue for now.

[AnthonyLeonardoGracio]

Hello @kittybwained,

Indeed, we can reproduce. We have had a lot of issues with problemMatchers in general, due to VS Code weird behavior in that area: these are hard to maintain, and to even test. We have tried different approaches, without success for now. Our goal is to use a standardized output format like SARIF to retrieve messages in the future.

We'll see if we can fix that with the current problemMatchers' mechanism for now, or at least suggest a workaround.

Thanks for the report and sorry for the inconvenience.