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Sema: missed simplifications of OPVs

bugObserved behavior contradicts documented or intended behaviorObserved behavior contradicts documented or intended behavior

frontendTokenization, parsing, AstGen, Sema, and Liveness.Tokenization, parsing, AstGen, Sema, and Liveness.

Status: Open.

#22419 In ziglang/zig;

· jacobly0 opened on Jan 5, 2025

"integer part of floating point value out of bounds" panic during f16 -> i32 conversion on macOS

arch-aarch6464-bit ARM64-bit ARM

backend-llvmThe LLVM backend outputs an LLVM IR Module.The LLVM backend outputs an LLVM IR Module.

bugObserved behavior contradicts documented or intended behaviorObserved behavior contradicts documented or intended behavior

miscompilationThe compiler reports success but produces semantically incorrect code.The compiler reports success but produces semantically incorrect code.

os-macos

upstreamAn issue with a third party project that Zig uses.An issue with a third party project that Zig uses.

Status: Open.

#22247 In ziglang/zig;

· linusg opened on Dec 15, 2024

segfault in compiler_rt rem_pio2_large

arch-x86_6464-bit x8664-bit x86

backend-llvmThe LLVM backend outputs an LLVM IR Module.The LLVM backend outputs an LLVM IR Module.

bugObserved behavior contradicts documented or intended behaviorObserved behavior contradicts documented or intended behavior

compiler-rt

miscompilationThe compiler reports success but produces semantically incorrect code.The compiler reports success but produces semantically incorrect code.

Status: Open.

#21802 In ziglang/zig;

· tauoverpi opened on Oct 25, 2024

Incorrect behavior on C function that returns struct which contains array of one or two doubles

arch-aarch6464-bit ARM64-bit ARM

arch-riscv32-bit and 64-bit RISC-V32-bit and 64-bit RISC-V

arch-wasm32-bit and 64-bit WebAssembly32-bit and 64-bit WebAssembly

arch-x86_6464-bit x8664-bit x86

bugObserved behavior contradicts documented or intended behaviorObserved behavior contradicts documented or intended behavior

miscompilationThe compiler reports success but produces semantically incorrect code.The compiler reports success but produces semantically incorrect code.

Status: Open.

#21245 In ziglang/zig;

· tatjam opened on Aug 29, 2024

Volatile not respected in some edge cases

bugObserved behavior contradicts documented or intended behaviorObserved behavior contradicts documented or intended behavior

miscompilationThe compiler reports success but produces semantically incorrect code.The compiler reports success but produces semantically incorrect code.

Status: Open.

#21033 In ziglang/zig;

· kibels opened on Aug 11, 2024

Segmentation fault when calling function pointer directly from packed struct

bugObserved behavior contradicts documented or intended behaviorObserved behavior contradicts documented or intended behavior

miscompilationThe compiler reports success but produces semantically incorrect code.The compiler reports success but produces semantically incorrect code.

Status: Open.

#20539 In ziglang/zig;

· mvenditto opened on Jul 8, 2024

@cVaArg() sporadically fails with f128 on 32-bit Windows

bugObserved behavior contradicts documented or intended behaviorObserved behavior contradicts documented or intended behavior

miscompilationThe compiler reports success but produces semantically incorrect code.The compiler reports success but produces semantically incorrect code.

os-windows

Status: Open.

#20470 In ziglang/zig;

· chung-leong opened on Jul 2, 2024

Incorrect 2D array to array of vectors conversion when given by a parameter.

bugObserved behavior contradicts documented or intended behaviorObserved behavior contradicts documented or intended behavior

miscompilationThe compiler reports success but produces semantically incorrect code.The compiler reports success but produces semantically incorrect code.

Status: Open.

#20453 In ziglang/zig;

· elijahimmer opened on Jun 29, 2024

Bad codegen (or calling convention?): Arguments pointed to on stack into tailcall

bugObserved behavior contradicts documented or intended behaviorObserved behavior contradicts documented or intended behavior

miscompilationThe compiler reports success but produces semantically incorrect code.The compiler reports success but produces semantically incorrect code.

Status: Open.

#9703 In ziglang/zig;

· N00byEdge opened on Sep 8, 2021

"bitcast packed union to integer" behavior test causing undefined behavior in the compiler

bugObserved behavior contradicts documented or intended behaviorObserved behavior contradicts documented or intended behavior

frontendTokenization, parsing, AstGen, Sema, and Liveness.Tokenization, parsing, AstGen, Sema, and Liveness.

miscompilationThe compiler reports success but produces semantically incorrect code.The compiler reports success but produces semantically incorrect code.

Status: Open.

#19384 In ziglang/zig;

· andrewrk opened on Mar 21, 2024

"comptime bitcast with fields following f80" behavior test causing undefined behavior in the compiler

bugObserved behavior contradicts documented or intended behaviorObserved behavior contradicts documented or intended behavior

frontendTokenization, parsing, AstGen, Sema, and Liveness.Tokenization, parsing, AstGen, Sema, and Liveness.

miscompilationThe compiler reports success but produces semantically incorrect code.The compiler reports success but produces semantically incorrect code.

Status: Open.

#19387 In ziglang/zig;

· andrewrk opened on Mar 22, 2024

"reinterpret extern union" behavior test causing undefined behavior in the compiler

bugObserved behavior contradicts documented or intended behaviorObserved behavior contradicts documented or intended behavior

frontendTokenization, parsing, AstGen, Sema, and Liveness.Tokenization, parsing, AstGen, Sema, and Liveness.

miscompilationThe compiler reports success but produces semantically incorrect code.The compiler reports success but produces semantically incorrect code.

Status: Open.

#19389 In ziglang/zig;

· andrewrk opened on Mar 22, 2024

Slice operation omits sentinel runtime safety check

bugObserved behavior contradicts documented or intended behaviorObserved behavior contradicts documented or intended behavior

frontendTokenization, parsing, AstGen, Sema, and Liveness.Tokenization, parsing, AstGen, Sema, and Liveness.

miscompilationThe compiler reports success but produces semantically incorrect code.The compiler reports success but produces semantically incorrect code.

Status: Open.

#19792 In ziglang/zig;

· amp-59 opened on Apr 28, 2024

Slice operations <code>slice_sentinel</code> and <code>slice_length</code> (with sentinel) produce runtime safety checks testing incorrect (underestimated) upper bounds

bugObserved behavior contradicts documented or intended behaviorObserved behavior contradicts documented or intended behavior

frontendTokenization, parsing, AstGen, Sema, and Liveness.Tokenization, parsing, AstGen, Sema, and Liveness.

miscompilationThe compiler reports success but produces semantically incorrect code.The compiler reports success but produces semantically incorrect code.

Status: Open.

#19794 In ziglang/zig;

· amp-59 opened on Apr 28, 2024

Slice operations <code>slice_sentinel</code> and <code>slice_length</code> (with sentinel) produce compile-time assertions testing incorrect (overestimated) upper bounds

bugObserved behavior contradicts documented or intended behaviorObserved behavior contradicts documented or intended behavior

miscompilationThe compiler reports success but produces semantically incorrect code.The compiler reports success but produces semantically incorrect code.

Status: Open.

#19795 In ziglang/zig;

· amp-59 opened on Apr 28, 2024

Slice operation produces runtime safety check with impossible success condition

bugObserved behavior contradicts documented or intended behaviorObserved behavior contradicts documented or intended behavior

frontendTokenization, parsing, AstGen, Sema, and Liveness.Tokenization, parsing, AstGen, Sema, and Liveness.

miscompilationThe compiler reports success but produces semantically incorrect code.The compiler reports success but produces semantically incorrect code.

Status: Open.

#19796 In ziglang/zig;

· amp-59 opened on Apr 28, 2024

Pointer arithmetic and slicing without end for zero-size types give wrong results

bugObserved behavior contradicts documented or intended behaviorObserved behavior contradicts documented or intended behavior

miscompilationThe compiler reports success but produces semantically incorrect code.The compiler reports success but produces semantically incorrect code.

Status: Open.

#20214 In ziglang/zig;

· weebcel opened on Jun 6, 2024

std lib test suite is not valgrind clean

bugObserved behavior contradicts documented or intended behaviorObserved behavior contradicts documented or intended behavior

contributor friendlyThis issue is limited in scope and/or knowledge of Zig internals.This issue is limited in scope and/or knowledge of Zig internals.

standard libraryThis issue involves writing Zig code for the standard library.This issue involves writing Zig code for the standard library.

Status: Open.

#24753 In ziglang/zig;

· andrewrk opened on Aug 8, 2025

"zig fetch" hang in deflate with specific .tar.gz archive

bugObserved behavior contradicts documented or intended behaviorObserved behavior contradicts documented or intended behavior

regressionIt worked in a previous version of Zig, but stopped working.It worked in a previous version of Zig, but stopped working.

Status: Open.

#24916 In ziglang/zig;

· bfredl opened on Aug 20, 2025

Assertion failure in Sema

bugObserved behavior contradicts documented or intended behaviorObserved behavior contradicts documented or intended behavior

frontendTokenization, parsing, AstGen, Sema, and Liveness.Tokenization, parsing, AstGen, Sema, and Liveness.

Status: Open.

#24940 In ziglang/zig;

· ifreund opened on Aug 21, 2025

Zig std nonfunctional on Windows after 0.15.1 update

bugObserved behavior contradicts documented or intended behaviorObserved behavior contradicts documented or intended behavior

os-windows

regressionIt worked in a previous version of Zig, but stopped working.It worked in a previous version of Zig, but stopped working.

Status: Open.

#24944 In ziglang/zig;

· trypsynth opened on Aug 21, 2025

translate_c: fix ternary operator output in C macros

Status: Open (in progress).

ziglang/zignumber 24664

#24664 In ziglang/zig;

· cmpute opened on Aug 2, 2025

std.Io.Reader.takeDelimiterExclusive() return error.StreamTooLong instead of error.EndOfStream

bugObserved behavior contradicts documented or intended behaviorObserved behavior contradicts documented or intended behavior

standard libraryThis issue involves writing Zig code for the standard library.This issue involves writing Zig code for the standard library.

Status: Open.

#24950 In ziglang/zig;

· truly-not-taken opened on Aug 22, 2025

<code>zig fmt --stdin</code> is broken on Windows (<code>File.Reader.getSize()</code> returns bogus values for pipes)

bugObserved behavior contradicts documented or intended behaviorObserved behavior contradicts documented or intended behavior

os-windows

regressionIt worked in a previous version of Zig, but stopped working.It worked in a previous version of Zig, but stopped working.

standard libraryThis issue involves writing Zig code for the standard library.This issue involves writing Zig code for the standard library.

Status: Open.

#24984 In ziglang/zig;

· castholm opened on Aug 24, 2025

Unable to build Windows DLL with output path being in a subdirectory

bugObserved behavior contradicts documented or intended behaviorObserved behavior contradicts documented or intended behavior

os-windows

regressionIt worked in a previous version of Zig, but stopped working.It worked in a previous version of Zig, but stopped working.

Status: Open.

#24993 In ziglang/zig;

· alexrp opened on Aug 25, 2025