zig

commit 13993c4f62d8603aa5a25de70e2d111a01cbfaab (tree)
parent 6d280dc1b0779209b4790da9e939d8254d11348a
Author: Matthew Lugg <mlugg@mlugg.co.uk>
Date:   Mon, 10 Nov 2025 12:56:35 +0000

compiler: warn when using -fincremental with LLVM backend

This configuration hasn't had much work put into it yet, so is all but
guaranteed to miscompile or crash. Since users are starting to try out
`-fincremental`, and LLVM is still the default backend in many cases,
it's worth having this warning to avoid bug reports like
https://github.com/ziglang/zig/issues/25873.

Diffstat:
M
src/main.zig
 | 
4
++++

1 file changed, 4 insertions(+), 0 deletions(-)
diff --git a/src/main.zig b/src/main.zig
@@ -3360,6 +3360,10 @@ fn buildOutputType(
         fatal("--debug-incremental requires -fincremental", .{});
     }
 
+    if (incremental and create_module.resolved_options.use_llvm) {
+        warn("-fincremental is currently unsupported by the LLVM backend; crashes or miscompilations are likely", .{});
+    }
+
     const cache_mode: Compilation.CacheMode = b: {
         // Once incremental compilation is the default, we'll want some smarter logic here,
         // considering things like the backend in use and whether there's a ZCU.