From 3fa5415253695001149ad65ae6f2ca8d0fa63565 Mon Sep 17 00:00:00 2001
From: martinhath <martinhath@users.noreply.github.com>
Date: Fri, 26 Aug 2022 10:37:17 +0200
Subject: [PATCH] Sema: ensure resolveTypeFields is called for optional and
 error union types

We call `sema.resolveTypeFields` in order to get the fields of structs
and unions inserted into their data structures. If it isn't called, it
can happen that the fields of a type is queried before those fields are
inserted into (for instance) `Module.Union.fields`, which would result in
a wrong 'no field named' error.

Fixes: #12486
---
 src/Sema.zig                 |  5 ++--
 test/behavior.zig            |  1 +
 test/behavior/bugs/12486.zig | 49 ++++++++++++++++++++++++++++++++++++
 3 files changed, 53 insertions(+), 2 deletions(-)
 create mode 100644 test/behavior/bugs/12486.zig

diff --git a/src/Sema.zig b/src/Sema.zig
index fc2a7f872a..2907999c25 100644
--- a/src/Sema.zig
+++ b/src/Sema.zig
@@ -16190,9 +16190,10 @@ fn fieldType(
     field_src: LazySrcLoc,
     ty_src: LazySrcLoc,
 ) CompileError!Air.Inst.Ref {
-    const resolved_ty = try sema.resolveTypeFields(block, ty_src, aggregate_ty);
-    var cur_ty = resolved_ty;
+    var cur_ty = aggregate_ty;
     while (true) {
+        const resolved_ty = try sema.resolveTypeFields(block, ty_src, cur_ty);
+        cur_ty = resolved_ty;
         switch (cur_ty.zigTypeTag()) {
             .Struct => {
                 if (cur_ty.isAnonStruct()) {
diff --git a/test/behavior.zig b/test/behavior.zig
index 12edd6f9a3..8f581f372e 100644
--- a/test/behavior.zig
+++ b/test/behavior.zig
@@ -84,6 +84,7 @@ test {
     _ = @import("behavior/bugs/12003.zig");
     _ = @import("behavior/bugs/12033.zig");
     _ = @import("behavior/bugs/12430.zig");
+    _ = @import("behavior/bugs/12486.zig");
     _ = @import("behavior/byteswap.zig");
     _ = @import("behavior/byval_arg_var.zig");
     _ = @import("behavior/call.zig");
diff --git a/test/behavior/bugs/12486.zig b/test/behavior/bugs/12486.zig
new file mode 100644
index 0000000000..f0d357efd1
--- /dev/null
+++ b/test/behavior/bugs/12486.zig
@@ -0,0 +1,49 @@
+const SomeEnum = union(enum) {
+    EnumVariant: u8,
+};
+
+const SomeStruct = struct {
+    struct_field: u8,
+};
+
+const OptEnum = struct {
+    opt_enum: ?SomeEnum,
+};
+
+const ErrEnum = struct {
+    err_enum: anyerror!SomeEnum,
+};
+
+const OptStruct = struct {
+    opt_struct: ?SomeStruct,
+};
+
+const ErrStruct = struct {
+    err_struct: anyerror!SomeStruct,
+};
+
+test {
+    _ = OptEnum{
+        .opt_enum = .{
+            .EnumVariant = 1,
+        },
+    };
+
+    _ = ErrEnum{
+        .err_enum = .{
+            .EnumVariant = 1,
+        },
+    };
+
+    _ = OptStruct{
+        .opt_struct = .{
+            .struct_field = 1,
+        },
+    };
+
+    _ = ErrStruct{
+        .err_struct = .{
+            .struct_field = 1,
+        },
+    };
+}