Commit c698e55754748fa9e97fed4fe279c604d3b381cd | zig

author	Matthew Lugg <mlugg@mlugg.co.uk> 2026-05-27 16:28:52+01:00
committer	Matthew Lugg <mlugg@mlugg.co.uk> 2026-05-28 09:03:10+01:00
log	c698e55754748fa9e97fed4fe279c604d3b381cd
tree	0423dfd6599219ab25e1d4dd9bb5b3dff4c601ea
parent	f60fe4dcb667cc638f4f8ea8fb20d11de3440671
signature	Commit is signed but in an unrecognized format.

Compilation: don't update C inputs on incremental updates

...at least, for now, so that the use case of performing incremental
updates to the *Zig* source code works without crashing the linker.
This works around https://codeberg.org/ziglang/zig/issues/32081.

2 files changed, 19 insertions(+), 4 deletions(-)

src
- Compilation.zig
- link.zig

src/Compilation.zig+16-4

 @@ -3008,10 +3008,19 @@ pub fn update(comp: *Compilation, main_progress_node: std.Progress.Node) UpdateE
     // For compiling C objects, we rely on the cache hash system to avoid duplicating work.
     // Add a Job for each C object.
-    try comp.c_object_work_queue.ensureUnusedCapacity(gpa, comp.c_object_table.count());
+    if (comp.bin_file != null and comp.bin_file.?.post_prelink) {
-    for (comp.c_object_table.keys()) |c_object| {
+        assert(comp.config.incremental);
-        comp.c_object_work_queue.pushBackAssumeCapacity(c_object);
+        // TODO: this indicates that we are using incremental compilation and this is not the first
-        try comp.appendFileSystemInput(try .fromUnresolved(arena, comp.dirs, &.{c_object.src.src_path}));
+        // incremental update. The incremental linkers do not (currently?) support updating C inputs
+        // incrementally. The frontend needs to learn to trigger a full rebuild if a C link input
+        // changes. For now, to avoid crashing the linker in this case, don't kick off C object
+        // updates if we've done prelink already. https://codeberg.org/ziglang/zig/issues/32081
+    } else {
+        try comp.c_object_work_queue.ensureUnusedCapacity(gpa, comp.c_object_table.count());
+        for (comp.c_object_table.keys()) |c_object| {
+            comp.c_object_work_queue.pushBackAssumeCapacity(c_object);
+            try comp.appendFileSystemInput(try .fromUnresolved(arena, comp.dirs, &.{c_object.src.src_path}));
+        }
     }
     for (comp.link_inputs) |input| if (input.path()) |path| {
 @@ -7595,6 +7604,9 @@ pub fn queuePrelinkTaskMode(comp: *Compilation, path: Cache.Path, must_link: boo
 /// Only valid to call during `update`.
 pub fn queuePrelinkTasks(comp: *Compilation, tasks: []const link.PrelinkTask) Io.Cancelable!void {
+    if (tasks.len > 0) {
+        if (comp.bin_file) |lf| assert(!lf.post_prelink);
+    }
     comp.link_prog_node.increaseEstimatedTotalItems(tasks.len);
     try comp.link_queue.enqueuePrelink(comp, tasks);
 }

src/link.zig+3

...	@@ -1205,6 +1205,7 @@ pub const File = struct {	...	@@ -1205,6 +1205,7 @@ pub const File = struct {
1205		1205
1206	pub fn loadInput(base: *File, input: Input) anyerror!void {	1206	pub fn loadInput(base: *File, input: Input) anyerror!void {
1207	if (base.tag == .lld) return;	1207	if (base.tag == .lld) return;
		1208	assert(!base.post_prelink);
1208	switch (base.tag) {	1209	switch (base.tag) {
1209	inline .elf, .elf2, .wasm => \|tag\| {	1210	inline .elf, .elf2, .wasm => \|tag\| {
1210	dev.check(tag.devFeature());	1211	dev.check(tag.devFeature());
...	@@ -1424,6 +1425,8 @@ pub fn doPrelinkTask(comp: *Compilation, task: PrelinkTask) void {	...	@@ -1424,6 +1425,8 @@ pub fn doPrelinkTask(comp: *Compilation, task: PrelinkTask) void {
1424	return;	1425	return;
1425	};	1426	};
1426		1427
		1428	assert(!base.post_prelink);
		1429
1427	var timer = comp.startTimer();	1430	var timer = comp.startTimer();
1428	defer if (timer.finish(io)) \|ns\| {	1431	defer if (timer.finish(io)) \|ns\| {
1429	comp.mutex.lockUncancelable(io);	1432	comp.mutex.lockUncancelable(io);