From dd01fe96d36a7cf898f04a55b820174d76588a32 Mon Sep 17 00:00:00 2001
From: Jacob Young <jacobly@ziglang.org>
Date: Tue, 1 Sep 2026 12:58:19 -0400
Subject: [PATCH] Dwarf2: track function resolution for deterministic ies debug
 info

Avoid calling `funcIesResolvedUnordered` before the frontend is
guaranteed to have set it.
---
 src/link/Dwarf2.zig | 23 ++++++++++++++++++-----
 src/link/Elf2.zig   |  6 ++++++
 2 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/src/link/Dwarf2.zig b/src/link/Dwarf2.zig
index 34f6b62c2637647a06b652e5ad0ae1e0c2d2d4b6..c282b59810e1942f8e8102ad2f867ba896732ae1 100644
--- a/src/link/Dwarf2.zig
+++ b/src/link/Dwarf2.zig
@@ -120,10 +120,13 @@ pub const Global = struct {
 };
 
 pub const Func = struct {
+    state: State,
     fde_ni: MappedFile.Node.Index.Optional,
     debug_info_ni: MappedFile.Node.Index.Optional,
     debug_line_ni: MappedFile.Node.Index.Optional,
 
+    pub const State = enum { unresolved, resolved };
+
     pub const Index = enum(u32) {
         _,
 
@@ -1419,6 +1422,7 @@ pub fn getFunc(dwarf: *Dwarf, nav: InternPool.Nav.Index) link.Error!Func.Index {
     const gpa = comp.gpa;
     const func_gop = try dwarf.funcs.getOrPut(gpa, nav);
     if (!func_gop.found_existing) func_gop.value_ptr.* = .{
+        .state = .unresolved,
         .fde_ni = .none,
         .debug_info_ni = .none,
         .debug_line_ni = .none,
@@ -1975,7 +1979,10 @@ pub fn updateComptimeNav(
         .func => |func| if (func.owner_nav == nav_index and func.generic_owner == .none) {
             const fi = try dwarf.getFunc(func.owner_nav);
             const f = fi.get(dwarf);
-            if (f.fde_ni != .none or f.debug_line_ni != .none) return;
+            switch (f.state) {
+                .unresolved => {},
+                .resolved => return,
+            }
             const elf = dwarf.lf.cast(.elf2).?;
             const debug_info_ni = f.debug_info_ni.unwrap().?;
             var di_nw: MappedFile.Node.Writer = undefined;
@@ -2837,7 +2844,14 @@ fn updateConstInner(
             defer zcu.gpa.free(name);
             try diw.writeUleb128(try dwarf.refAbbrevCode(.inferred_error_set_type));
             try dwarf.strp(&dwarf.debug_str, di_nw, name);
-            try dwarf.refType(pt, di_nw, switch (ip.funcIesResolvedUnordered(func)) {
+            try dwarf.refType(pt, di_nw, switch (ies: {
+                const fi = dwarf.getFuncIfExists(ip.indexToKey(func).func.owner_nav) orelse
+                    break :ies .none;
+                break :ies switch (fi.get(dwarf).state) {
+                    .unresolved => .none,
+                    .resolved => ip.funcIesResolvedUnordered(func),
+                };
+            }) {
                 .none => .anyerror,
                 else => |ies| .fromInterned(ies),
             });
@@ -3563,10 +3577,9 @@ fn exprLoc(dwarf: *Dwarf, nw: *MappedFile.Node.Writer, loc: Loc) link.EmitError!
 
 fn strp(dwarf: *Dwarf, s: *Str, nw: *MappedFile.Node.Writer, str: []const u8) link.EmitError!void {
     const comp = dwarf.lf.comp;
-    const mf = &dwarf.lf.cast(.elf2).?.mf;
-    try dwarf.secOffset(nw, s.ni.unwrap().?, s.get(comp.gpa, mf, str) catch |err| switch (err) {
+    try dwarf.secOffset(nw, s.ni.unwrap().?, s.get(comp.gpa, nw.mf, str) catch |err| switch (err) {
         error.MappedFileIo => return comp.link_diags.fail("failed to write output file: {t}", .{
-            mf.io_err.?,
+            nw.mf.io_err.?,
         }),
         else => |e| return e,
     });
diff --git a/src/link/Elf2.zig b/src/link/Elf2.zig
index 27721ed9eec71deddc9db7cdfc73ca2cf8fa9fdd..ffbe21e1832936a1260c1f3e552bf3c998219ad8 100644
--- a/src/link/Elf2.zig
+++ b/src/link/Elf2.zig
@@ -8926,6 +8926,7 @@ fn updateFuncInner(
             debug.pt = pt;
             debug.any_children = false;
             debug.blocks = .empty;
+            dwarf_func.state = .resolved;
 
             const debug_info_ni = dwarf_func.debug_info_ni.unwrap().?;
             try dwarf.decls.put(zcu.comp.gpa, src_inst, .{
@@ -9020,6 +9021,11 @@ fn updateFuncInner(
                         );
                 }
                 debug.wip_nav.finishDebugFrameFde(func_length);
+                if (func.analysisUnordered(ip).inferred_error_set) {
+                    const ies = ip.getIfExists(.{ .inferred_error_set_type = func_index }).?;
+                    if (elf.dwarf.const_pool.getIfExists(ies)) |cpi|
+                        try elf.updateConstInner(pt, cpi, ies);
+                }
             },
             .none => {},
         }
-- 
2.54.0