From 77a5f888be664f9ef09e2c93f52338448e992e00 Mon Sep 17 00:00:00 2001
From: Andrew Kelley <andrew@ziglang.org>
Date: Tue, 3 Sep 2019 22:09:47 -0400
Subject: [PATCH] emit a compile error if a test becomes async

See #3117
---
 src/analyze.cpp |  2 +-
 src/analyze.hpp |  2 ++
 src/codegen.cpp | 10 ++++++++++
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/analyze.cpp b/src/analyze.cpp
index 2fd540a64f..e1d6b59ddf 100644
--- a/src/analyze.cpp
+++ b/src/analyze.cpp
@@ -4195,7 +4195,7 @@ bool fn_is_async(ZigFn *fn) {
     return fn->inferred_async_node != inferred_async_none;
 }
 
-static void add_async_error_notes(CodeGen *g, ErrorMsg *msg, ZigFn *fn) {
+void add_async_error_notes(CodeGen *g, ErrorMsg *msg, ZigFn *fn) {
     assert(fn->inferred_async_node != nullptr);
     assert(fn->inferred_async_node != inferred_async_checking);
     assert(fn->inferred_async_node != inferred_async_none);
diff --git a/src/analyze.hpp b/src/analyze.hpp
index dc702167e7..9f2c984992 100644
--- a/src/analyze.hpp
+++ b/src/analyze.hpp
@@ -256,4 +256,6 @@ Error type_val_resolve_zero_bits(CodeGen *g, ConstExprValue *type_val, ZigType *
 ZigType *resolve_union_field_type(CodeGen *g, TypeUnionField *union_field);
 ZigType *resolve_struct_field_type(CodeGen *g, TypeStructField *struct_field);
 
+void add_async_error_notes(CodeGen *g, ErrorMsg *msg, ZigFn *fn);
+
 #endif
diff --git a/src/codegen.cpp b/src/codegen.cpp
index 1710a3b3fd..d1499592d2 100644
--- a/src/codegen.cpp
+++ b/src/codegen.cpp
@@ -8905,6 +8905,15 @@ static void create_test_compile_var_and_add_test_runner(CodeGen *g) {
     for (size_t i = 0; i < g->test_fns.length; i += 1) {
         ZigFn *test_fn_entry = g->test_fns.at(i);
 
+        if (fn_is_async(test_fn_entry)) {
+            ErrorMsg *msg = add_node_error(g, test_fn_entry->proto_node,
+                buf_create_from_str("test functions cannot be async"));
+            add_error_note(g, msg, test_fn_entry->proto_node,
+                buf_sprintf("this restriction may be lifted in the future. See https://github.com/ziglang/zig/issues/3117 for more details"));
+            add_async_error_notes(g, msg, test_fn_entry);
+            continue;
+        }
+
         ConstExprValue *this_val = &test_fn_array->data.x_array.data.s_none.elements[i];
         this_val->special = ConstValSpecialStatic;
         this_val->type = struct_type;
@@ -8924,6 +8933,7 @@ static void create_test_compile_var_and_add_test_runner(CodeGen *g) {
         fn_field->data.x_ptr.mut = ConstPtrMutComptimeConst;
         fn_field->data.x_ptr.data.fn.fn_entry = test_fn_entry;
     }
+    report_errors_and_maybe_exit(g);
 
     ConstExprValue *test_fn_slice = create_const_slice(g, test_fn_array, 0, g->test_fns.length, true);