From 60d6037f236379e521ccb7a8e1b7d24ed469ac3f Mon Sep 17 00:00:00 2001
From: Andrew Kelley <andrew@ziglang.org>
Date: Fri, 11 Mar 2022 20:44:10 -0700
Subject: [PATCH] Sema: fix inline/comptime function calls with inferred errors

---
 src/Module.zig | 15 +++++++++++++++
 src/Sema.zig   | 24 +++++++++++-------------
 2 files changed, 26 insertions(+), 13 deletions(-)

diff --git a/src/Module.zig b/src/Module.zig
index b3e0344d77..868ce578eb 100644
--- a/src/Module.zig
+++ b/src/Module.zig
@@ -1542,6 +1542,21 @@ pub const Fn = struct {
         // const zir = func.owner_decl.getFileScope().zir;
         return func.param_names[index];
     }
+
+    pub fn hasInferredErrorSet(func: Fn) bool {
+        const zir = func.owner_decl.getFileScope().zir;
+        const zir_tags = zir.instructions.items(.tag);
+        switch (zir_tags[func.zir_body_inst]) {
+            .func => return false,
+            .func_inferred => return true,
+            .extended => {
+                const extended = zir.instructions.items(.data)[func.zir_body_inst].extended;
+                const small = @bitCast(Zir.Inst.ExtendedFunc.Small, extended.small);
+                return small.is_inferred_error;
+            },
+            else => unreachable,
+        }
+    }
 };
 
 pub const Var = struct {
diff --git a/src/Sema.zig b/src/Sema.zig
index 31295707de..82acbab9e5 100644
--- a/src/Sema.zig
+++ b/src/Sema.zig
@@ -4666,20 +4666,18 @@ fn analyzeCall(
         const bare_return_type = try sema.analyzeAsType(&child_block, ret_ty_src, ret_ty_inst);
         // Create a fresh inferred error set type for inline/comptime calls.
         const fn_ret_ty = blk: {
-            if (func_ty_info.return_type.castTag(.error_union)) |payload| {
-                if (payload.data.error_set.tag() == .error_set_inferred) {
-                    const node = try sema.gpa.create(Module.Fn.InferredErrorSetListNode);
-                    node.data = .{ .func = module_fn };
-                    if (parent_func) |some| {
-                        some.inferred_error_sets.prepend(node);
-                    }
-
-                    const error_set_ty = try Type.Tag.error_set_inferred.create(sema.arena, &node.data);
-                    break :blk try Type.Tag.error_union.create(sema.arena, .{
-                        .error_set = error_set_ty,
-                        .payload = bare_return_type,
-                    });
+            if (module_fn.hasInferredErrorSet()) {
+                const node = try sema.gpa.create(Module.Fn.InferredErrorSetListNode);
+                node.data = .{ .func = module_fn };
+                if (parent_func) |some| {
+                    some.inferred_error_sets.prepend(node);
                 }
+
+                const error_set_ty = try Type.Tag.error_set_inferred.create(sema.arena, &node.data);
+                break :blk try Type.Tag.error_union.create(sema.arena, .{
+                    .error_set = error_set_ty,
+                    .payload = bare_return_type,
+                });
             }
             break :blk bare_return_type;
         };