Why are tabs allowed in code, but not in comments?

floooh · September 25, 2025, 9:50am

I just got this interesting bug report for the sokol-shdc shader compiler:

error: comment contains invalid byte: '\t'

opened 07:46PM - 24 Sep 25 UTC

This is a weird one, apparently zig 0.15.1 does not allow that byte in comments.… I was creating a shader with the inverse method and SPIRV Cross https://github.com/KhronosGroup/SPIRV-Cross/blob/b0fe8e8f5b64fbc1478d7734c7e89501ee98a9a7/reference/shaders-msl/comp/inverse.comp#L27 has a tab right before "// The adjoint matrix (inverse after dividing by determinant)" so when shader is compiled to glsl.zig it breaks. you can reproduce it in sokol-zig in the blend.glsl wrap the mvp matrix with inverse and run `zig build run-blend` maybe sokol tools could replace \t bytes by a space or maybe this should be a bug reported in ziglang to allow that?

…long story short: a tab slips into a comment in a generated Zig file via some very obscure code-generation situation involving third-party libraries, and this causes a Zig compilation error.

So I immediately thought “yeah figures, Zig doesn’t allow tabs”, but that’s outdated information, tabs are actually allowed in regular code now.

But now the confusing thing: tabs in comments are still a compilation error. Is there a rational explanation for this, or just an oversight?

AndrewKraevskii · September 25, 2025, 11:13am

some relevant facts:
0.7.0 ignored tabs in comments but complained about tabs in source code Compiler Explorer.
in 0.10.0 compiler started to accept tabs in code and in comments. Compiler Explorer
And finally in 0.14.0 compiler started reject tabs in comments but not in code. Compiler Explorer

Also issue about it grammar clarifications regarding tabs and carriage returns · Issue #38 · ziglang/zig-spec · GitHub