[Bug] Unknown C standard control flag: c23

[laxsjo]

Brief Issue Summary

Reopen of #691. Makefile tools doesn't recognize the c23 or gnu23 standards.
According to this comment, #691 (comment), the previous issue should have been fixed by #763, but it only adds support for the relevant c++ standards, not c23. Anyway, as you can see in the logs below, the extension still doesn't recognize c23.

The logs was from running clean configuartion on a project which passes -std=c23 to GCC.

Debug Log

Saving opened files before build.
Loading configurations from cache is not necessary.
Generating configuration cache with command: 'make --dry-run --always-make --keep-going --print-directory'
Writing the dry-run output: /home/rasmus/.config/Code/User/workspaceStorage/cfa79cd936445168a6e9ef7ce7c327b3/ms-vscode.makefile-tools/dryrun.log
Spawning child process with:
 process name: make
 process args: --dry-run,--always-make,--keep-going,--print-directory
 working directory: /home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up
 shell type: default
Generating dry-run elapsed time: 0.066
Preprocessing: "/home/rasmus/.config/Code/User/workspaceStorage/cfa79cd936445168a6e9ef7ce7c327b3/ms-vscode.makefile-tools/dryrun.log"
Preprocess elapsed time: 0
Parsing for IntelliSense.
Updating the CppTools IntelliSense Configuration Provider.
Parsing dry-run output for CppTools Custom Configuration Provider.
Analyzing line: make: Entering directory '/home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up'
MAKE -C: entering directory /home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up
Found compiler command: gcc -I/nix/store/6cps82m63w3vd1d5px3md2kcdjq9nsdz-csfml-3.0.0/include -Isrc -Wall -std=c23 -c src/garment.c -o build/garment.o
Unknown C standard control flag: c23
Sending configuration for file /home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up/src/garment.c -----------------------------------
    Defines: 
    Includes: /nix/store/6cps82m63w3vd1d5px3md2kcdjq9nsdz-csfml-3.0.0/include;/home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up/src
    Force Includes: 
    Standard: undefined
    IntelliSense Mode: undefined
    Compiler Path: /nix/store/kbw2j1vag664b3sj3rjwz9v53cqx87sb-gcc-wrapper-15.2.0/bin/gcc
    Compiler Arguments: -Wall;-c;src/garment.c;-o;build/garment.o
---------------------------------------------------------------------------------------------------
Found compiler command: gcc -I/nix/store/6cps82m63w3vd1d5px3md2kcdjq9nsdz-csfml-3.0.0/include -Isrc -Wall -std=c23 -c src/types/bounds.c -o build/types/bounds.o
Unknown C standard control flag: c23
Sending configuration for file /home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up/src/types/bounds.c -----------------------------------
    Defines: 
    Includes: /nix/store/6cps82m63w3vd1d5px3md2kcdjq9nsdz-csfml-3.0.0/include;/home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up/src
    Force Includes: 
    Standard: undefined
    IntelliSense Mode: undefined
    Compiler Path: /nix/store/kbw2j1vag664b3sj3rjwz9v53cqx87sb-gcc-wrapper-15.2.0/bin/gcc
    Compiler Arguments: -Wall;-c;src/types/bounds.c;-o;build/types/bounds.o
---------------------------------------------------------------------------------------------------
Found compiler command: gcc -I/nix/store/6cps82m63w3vd1d5px3md2kcdjq9nsdz-csfml-3.0.0/include -Isrc -Wall -std=c23 -c src/main.c -o build/main.o
Unknown C standard control flag: c23
Sending configuration for file /home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up/src/main.c -----------------------------------
    Defines: 
    Includes: /nix/store/6cps82m63w3vd1d5px3md2kcdjq9nsdz-csfml-3.0.0/include;/home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up/src
    Force Includes: 
    Standard: undefined
    IntelliSense Mode: undefined
    Compiler Path: /nix/store/kbw2j1vag664b3sj3rjwz9v53cqx87sb-gcc-wrapper-15.2.0/bin/gcc
    Compiler Arguments: -Wall;-c;src/main.c;-o;build/main.o
---------------------------------------------------------------------------------------------------
Found compiler command: gcc -I/nix/store/6cps82m63w3vd1d5px3md2kcdjq9nsdz-csfml-3.0.0/include -Isrc -Wall -std=c23 -c src/ui/component.c -o build/ui/component.o
Unknown C standard control flag: c23
Sending configuration for file /home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up/src/ui/component.c -----------------------------------
    Defines: 
    Includes: /nix/store/6cps82m63w3vd1d5px3md2kcdjq9nsdz-csfml-3.0.0/include;/home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up/src
    Force Includes: 
    Standard: undefined
    IntelliSense Mode: undefined
    Compiler Path: /nix/store/kbw2j1vag664b3sj3rjwz9v53cqx87sb-gcc-wrapper-15.2.0/bin/gcc
    Compiler Arguments: -Wall;-c;src/ui/component.c;-o;build/ui/component.o
---------------------------------------------------------------------------------------------------
Found compiler command: gcc -I/nix/store/6cps82m63w3vd1d5px3md2kcdjq9nsdz-csfml-3.0.0/include -Isrc -Wall -std=c23 -c src/ui/app.c -o build/ui/app.o
Unknown C standard control flag: c23
Sending configuration for file /home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up/src/ui/app.c -----------------------------------
    Defines: 
    Includes: /nix/store/6cps82m63w3vd1d5px3md2kcdjq9nsdz-csfml-3.0.0/include;/home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up/src
    Force Includes: 
    Standard: undefined
    IntelliSense Mode: undefined
    Compiler Path: /nix/store/kbw2j1vag664b3sj3rjwz9v53cqx87sb-gcc-wrapper-15.2.0/bin/gcc
    Compiler Arguments: -Wall;-c;src/ui/app.c;-o;build/ui/app.o
---------------------------------------------------------------------------------------------------
Found compiler command: gcc build/garment.o build/types/bounds.o build/main.o build/ui/component.o build/ui/app.o -L/nix/store/6cps82m63w3vd1d5px3md2kcdjq9nsdz-csfml-3.0.0/lib -lcsfml-graphics -lcsfml-window -lcsfml-audio -lcsfml-system -o program
Analyzing line: make: Leaving directory '/home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up'
POPD command or end of MAKE -C: leaving directory /home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up and entering directory /home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up
Sending Workspace Browse Configuration: -----------------------------------
    Browse Path: /home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up/src;/home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up/src/types;/home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up/src/ui;/nix/store/6cps82m63w3vd1d5px3md2kcdjq9nsdz-csfml-3.0.0/include
    Standard: undefined
    Compiler Path: /nix/store/kbw2j1vag664b3sj3rjwz9v53cqx87sb-gcc-wrapper-15.2.0/bin/gcc
    Compiler Arguments: -Wall;-c;src/ui/app.c;-o;build/ui/app.o
----------------------------------------------------------------------------
Parsing for IntelliSense elapsed time: 0.436
Parsing for launch targets.
Analyzing line: make: Entering directory '/home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up'
MAKE -C: entering directory /home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up
Found linker command: gcc build/garment.o build/types/bounds.o build/main.o build/ui/component.o build/ui/app.o -L/nix/store/6cps82m63w3vd1d5px3md2kcdjq9nsdz-csfml-3.0.0/lib -lcsfml-graphics -lcsfml-window -lcsfml-audio -lcsfml-system -o program
Producing target binary: program
Adding launch configuration:
/home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up>program()
Analyzing line: make: Leaving directory '/home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up'
POPD command or end of MAKE -C: leaving directory /home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up and entering directory /home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up
Analyzing line: make: Entering directory '/home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up'
MAKE -C: entering directory /home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up
Analyzing line: make: Leaving directory '/home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up'
POPD command or end of MAKE -C: leaving directory /home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up and entering directory /home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up
Found the following 1 launch targets defined in the makefile: /home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up>program()
Complete list of launch targets: /home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up>program()
Parsing for launch targets elapsed time: 0.021
Generating parse content for build targets.
Generating targets information with command: 'make all --print-data-base --no-builtin-variables --no-builtin-rules --question'
Writing the dry-run output: /home/rasmus/.config/Code/User/workspaceStorage/cfa79cd936445168a6e9ef7ce7c327b3/ms-vscode.makefile-tools/targets.log
Spawning child process with:
 process name: make
 process args: all,--print-data-base,--no-builtin-variables,--no-builtin-rules,--question
 working directory: /home/rasmus/projects/school/DD1349-proj-inda/drivfar-dress-up
 shell type: default
Generating dry-run elapsed time: 0.069
Parsing for build targets from: "/home/rasmus/.config/Code/User/workspaceStorage/cfa79cd936445168a6e9ef7ce7c327b3/ms-vscode.makefile-tools/targets.log"
Found the following 12 build targets defined in the makefile: all;build/garment.o;build/main.o;build/tester;build/types/bounds.o;build/ui/app.o;build/ui/component.o;check-deps;check-fmt;clean;fmt;program
Complete list of build targets: all;build/garment.o;build/main.o;build/tester;build/types/bounds.o;build/ui/app.o;build/ui/component.o;check-deps;check-fmt;clean;fmt;program
Parsing build targets elapsed time: 0.001
Configure finished. The status for all the subphases that ran:
generateParseContent: return code = 0, elapsed time = 0.066
preprocessParseContent: return code = 0, elapsed time = 0
parseIntelliSense: return code = 0, elapsed time = 0.436
parseLaunch: return code = 0, elapsed time = 0.021
dryrunTargets: return code = 0, elapsed time = 0.069
parseTargets: return code = 0, elapsed time = 0.001
Configure succeeded.
Configure elapsed time: 0.596
Sending telemetry: eventName = configure
properties: firstTime = "false",makeDryRun = "true",readCache = "true",isClean = "true",processTargetsSeparately = "false",resetBuildTarget = "false",triggeredBy = "command pallette (clean configure)",buildTarget = "(unset)"
measures: numberBuildTargets = "12",numberLaunchTargets = "1",numberIndexedSourceFiles = "5",numberMakefileConfigurations = "0",totalElapsedTime = "0.596",exitCode = "0",generateParseContent.exitCode = "0",generateParseContent.elapsed = "0.066",preprocessParseContent.exitCode = "0",preprocessParseContent.elapsed = "0",parseIntelliSense.exitCode = "0",parseIntelliSense.elapsed = "0.436",parseLaunch.exitCode = "0",parseLaunch.elapsed = "0.021",dryrunTargets.exitCode = "0",dryrunTargets.elapsed = "0.069",parseTargets.exitCode = "0",parseTargets.elapsed = "0.001"

Additional Information

Identifier: ms-vscode.makefile-tools
Version: 0.13.23
Last Updated: 16 minutes ago

[yanghhhhhhh]

Hi @laxsjo , thanks for reporting issue here!
We can reproduce this issue on Visual Studio Code v1.115.0 + Makefile Tools v0.12.17 release version.

Repro Steps:

1. Download the project(makefile-c23-mre.zip) and open it.
2. Run command "Makefile: Configure" and observe the result.

Details please see following video:

Screencast.from.2026-04-09.14-19-28.webm

FYI: @gcampbell-msft

[snehara99]

@laxsjo The fix for this should be available in the pre-release channel sometime tomorrow. please try it out and let me know if you have any issues

[laxsjo]

I think it works now! At least the output from C/C++: Log Diagnostics suggests that C23 has been configured. Some features (like constexpr) still don't work, but I assume that's due to issues in cpptools.