Sema: Prevent tail calls of std.builtin.returnError().
LLVM 20 started tail-calling it in some of our test cases, resulting in:
error: AndMyCarIsOutOfGas
/home/alexrp/Source/ziglang/zig-llvm20/repro.zig:2:5: 0x103ef9d in main (repro)
return error.TheSkyIsFalling;
^
/home/alexrp/Source/ziglang/zig-llvm20/repro.zig:6:5: 0x103efa5 in main (repro)
return error.AndMyCarIsOutOfGas;
^
/home/alexrp/Source/ziglang/zig-llvm20/lib/std/start.zig:656:37: 0x103ee83 in posixCallMainAndExit (repro)
const result = root.main() catch |err| {
^
instead of the expected:
error: AndMyCarIsOutOfGas
/home/alexrp/Source/ziglang/zig-llvm20/repro.zig:2:5: 0x103f00d in main (repro)
return error.TheSkyIsFalling;
^
/home/alexrp/Source/ziglang/zig-llvm20/repro.zig:6:5: 0x103f015 in main (repro)
return error.AndMyCarIsOutOfGas;
^
/home/alexrp/Source/ziglang/zig-llvm20/repro.zig:11:9: 0x103f01d in main (repro)
try bar();
^
7415739e36Alex Rønne Petersen committed on 4/4/2025, 4:08:10 AMparent82b9d9c