From 974737f26bf722c902f9d2a4fe8344c0129f70b2 Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Mon, 12 Jul 2021 10:40:11 +0300
Subject: [PATCH] vfmt: keep `module mymodule ... x := []thread MyStruct{}` as
 it is

---
 vlib/v/ast/types.v                          | 15 ++++++++++++++-
 vlib/v/fmt/tests/thread_in_a_module_keep.vv | 17 +++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)
 create mode 100644 vlib/v/fmt/tests/thread_in_a_module_keep.vv

diff --git a/vlib/v/ast/types.v b/vlib/v/ast/types.v
index 9f5acdb766..d6f7fb7eeb 100644
--- a/vlib/v/ast/types.v
+++ b/vlib/v/ast/types.v
@@ -865,6 +865,15 @@ pub fn (mytable &Table) type_to_code(t Type) string {
 pub fn (t &Table) type_to_str_using_aliases(typ Type, import_aliases map[string]string) string {
 	sym := t.get_type_symbol(typ)
 	mut res := sym.name
+	// Note, that the duplication of code in some of the match branches here
+	// is VERY deliberate. DO NOT be tempted to use `else {}` instead, because
+	// that strongly reduces the usefullness of the exhaustive checking that
+	// match does.
+	//    Using else{} here led to subtle bugs in vfmt discovered *months*
+	// after the original code was written.
+	//    It is important that each case here is handled *explicitly* and
+	// *clearly*, and that when a new kind is added, it should also be handled
+	// explicitly.
 	match sym.kind {
 		.int_literal, .float_literal {
 			res = sym.name
@@ -989,7 +998,11 @@ pub fn (t &Table) type_to_str_using_aliases(typ Type, import_aliases map[string]
 			}
 			return 'void'
 		}
-		else {
+		.thread {
+			res = 'thread ' +
+				t.type_to_str_using_aliases(sym.thread_info().return_type, import_aliases)
+		}
+		.alias, .any, .sum_type, .interface_, .size_t, .aggregate, .placeholder, .enum_ {
 			res = t.shorten_user_defined_typenames(res, import_aliases)
 		}
 	}
diff --git a/vlib/v/fmt/tests/thread_in_a_module_keep.vv b/vlib/v/fmt/tests/thread_in_a_module_keep.vv
new file mode 100644
index 0000000000..41e7ea69c5
--- /dev/null
+++ b/vlib/v/fmt/tests/thread_in_a_module_keep.vv
@@ -0,0 +1,17 @@
+module my_module
+
+import another
+import other as ooo
+
+pub fn do_something() {
+	mut simples := []MyStruct{}
+	//
+	mut threads := []thread MyStruct{}
+	threads.wait()
+	//
+	mut another_threads := []thread another.MyStruct{}
+	another_threads.wait()
+	//
+	mut other_threads := []thread ooo.MyStruct{}
+	other_threads.wait()
+}