Crashing & Leaking Build Script Compilation with Zig 0.15.2

[rcalixte]

Zig Version

0.15.2

Steps to Reproduce and Observed Behavior

• Clone libqt6zig-examples or libqt6c-examples
• Run zig build -h or zig build -l or similar, no need to install any dependencies or actually try to compile any of the examples

The build script process gets stuck at Configure, pegging the CPU for the thread it's running on and continuing to leak more memory until it's killed or halted. A debug build of the compiler built on tag 0.15.2 reproduces the issue as well but without any additional information.

A backtrace from gdb from the stuck operation using the Debug mode build of the compiler when run on the unmodified build.zig currently on master for libqt6c-examples:

(gdb) attach 4174277
Attaching to process 4174277
[New LWP 4174278]
0x00000000010fcfe1 in mem.Allocator.dupe__anon_5528 (allocator=..., T=<optimized out>, m=...)
(gdb) bt
#0  0x00000000010fcfe1 in mem.Allocator.dupe__anon_5528 (allocator=..., T=<optimized out>, m=...)
#1  0x0000000001205153 in build.build (b=0x7f7d845df418) at build.zig:53
#2  0x000000000120ae4b in Build.runBuild__anon_23469 (b=0x7f7d845df418, build_zig=<optimized out>)
#3  0x00000000011e7ff2 in build_runner.main ()
#4  0x00000000011eec6a in start.posixCallMainAndExit (argc_argv_ptr=0x7ffdf4984790)
#5  0x00000000011cd352 in start._start ()

I've tried commenting out portions of the build to see if there was anything that turned up but nothing did.

This has been reproduced so far on:

• Debian 13 x86_64
• FreeBSD 14 x86_64 & aarch64
• Void x86_64

Expected Behavior

The help menu or build steps should display and the compilation of the examples should execute as well. With no changes, 0.15.1 works as expected.

[rcalixte]

Inadvertent breaking changes were included in 0.15.2:

https://zsf.zulipchat.com/#narrow/channel/454371-std/topic/.E2.9C.94.20is.20takeDelimiterExclusive.20broken.3F/with/544414196

The release has been pulled from the website as well.