From 3b60a6de2fd68d7d02de7a10b8b88c919aa088f0 Mon Sep 17 00:00:00 2001
From: Veikka Tuominen <git@vexu.eu>
Date: Tue, 18 Oct 2022 13:56:20 +0300
Subject: [PATCH] Sema: fix using runtime instructions inside typeof in
 comptime only blocks

Closes #13210
Follow up to 3ccd4907fbcd04ecddffb618a4b14581fd080279
---
 src/Sema.zig                        |  8 +++++++-
 test/behavior/sizeof_and_typeof.zig | 24 ++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/src/Sema.zig b/src/Sema.zig
index 8945bc6bed..76e7e779e7 100644
--- a/src/Sema.zig
+++ b/src/Sema.zig
@@ -6433,7 +6433,7 @@ fn analyzeInlineCallArg(
                     .ty = param_ty,
                     .val = arg_val,
                 };
-            } else if ((try sema.resolveMaybeUndefVal(arg_block, arg_src, casted_arg) == null) or
+            } else if (((try sema.resolveMaybeUndefVal(arg_block, arg_src, casted_arg)) == null) or
                 try sema.typeRequiresComptime(param_ty) or zir_tags[inst] == .param_comptime)
             {
                 try sema.inst_map.putNoClobber(sema.gpa, inst, casted_arg);
@@ -14521,6 +14521,12 @@ fn zirClosureGet(
         return sema.failWithOwnedErrorMsg(msg);
     }
 
+    if (tv.val.tag() == .unreachable_value) {
+        assert(block.is_typeof);
+        // We need a dummy runtime instruction with the correct type.
+        return block.addTy(.alloc, tv.ty);
+    }
+
     return sema.addConstant(tv.ty, tv.val);
 }
 
diff --git a/test/behavior/sizeof_and_typeof.zig b/test/behavior/sizeof_and_typeof.zig
index 01501b05b2..0c0069b28f 100644
--- a/test/behavior/sizeof_and_typeof.zig
+++ b/test/behavior/sizeof_and_typeof.zig
@@ -314,3 +314,27 @@ test "lazy size cast to float" {
 test "bitSizeOf comptime_int" {
     try expect(@bitSizeOf(comptime_int) == 0);
 }
+
+test "runtime instructions inside typeof in comptime only scope" {
+    if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest;
+    if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest;
+
+    {
+        var y: i8 = 2;
+        const i: [2]i8 = [_]i8{ 1, y };
+        const T = struct {
+            a: @TypeOf(i) = undefined, // causes crash
+            b: @TypeOf(i[0]) = undefined, // causes crash
+        };
+        try expect(@TypeOf((T{}).a) == [2]i8);
+        try expect(@TypeOf((T{}).b) == i8);
+    }
+    {
+        var y: i8 = 2;
+        const i = .{ 1, y };
+        const T = struct {
+            b: @TypeOf(i[1]) = undefined,
+        };
+        try expect(@TypeOf((T{}).b) == i8);
+    }
+}