checker, cgen: fix generic map with generic type key (#12859)

vlib/v/checker/checker.v

@@ -4593,8 +4593,8 @@ pub fn (mut c Checker) map_init(mut node ast.MapInit) ast.Type {
 		info := c.table.get_type_symbol(node.typ).map_info()
 		c.ensure_type_exists(info.key_type, node.pos) or {}
 		c.ensure_type_exists(info.value_type, node.pos) or {}
-		node.key_type = c.unwrap_generic(info.key_type)
-		node.value_type = c.unwrap_generic(info.value_type)
+		node.key_type = info.key_type
+		node.value_type = info.value_type
 		return node.typ
 	}
 	if node.keys.len > 0 && node.vals.len > 0 {

vlib/v/gen/c/cgen.v

@@ -4794,10 +4794,12 @@ fn (mut g Gen) match_expr_classic(node ast.MatchExpr, is_expr bool, cond_var str
 }
 
 fn (mut g Gen) map_init(node ast.MapInit) {
-	key_typ_str := g.typ(node.key_type)
-	value_typ_str := g.typ(node.value_type)
-	value_typ := g.table.get_type_symbol(node.value_type)
-	key_typ := g.table.get_final_type_symbol(node.key_type)
+	unwrap_key_typ := g.unwrap_generic(node.key_type)
+	unwrap_val_typ := g.unwrap_generic(node.value_type)
+	key_typ_str := g.typ(unwrap_key_typ)
+	value_typ_str := g.typ(unwrap_val_typ)
+	value_typ := g.table.get_type_symbol(unwrap_val_typ)
+	key_typ := g.table.get_final_type_symbol(unwrap_key_typ)
 	hash_fn, key_eq_fn, clone_fn, free_fn := g.map_fn_ptrs(key_typ)
 	size := node.vals.len
 	mut shared_styp := '' // only needed for shared &[]{...}

vlib/v/tests/generics_map_with_generic_type_key_test.v

@@ -0,0 +1,34 @@
+fn counts<T>(variables []T) map[T]int {
+	mut tally := map[T]int{}
+	for var in variables {
+		tally[var]++
+	}
+	return tally
+}
+
+fn str_fn() {
+	a2 := ['1', '2', '3', '4', '5', '3', '1']
+	ret := counts(a2)
+	println(ret)
+	assert ret.len == 5
+}
+
+fn int_fn() {
+	a1 := [1, 2, 3, 4, 5, 2, 3]
+	ret := counts(a1)
+	println(ret)
+	assert ret.len == 5
+}
+
+fn float_fn() {
+	a3 := [0.1, 0.02, 0.3, 4.0, 0.3]
+	ret := counts(a3)
+	println(ret)
+	assert ret.len == 4
+}
+
+fn test_generic_map_with_generic_type_key() {
+	str_fn()
+	float_fn()
+	int_fn()
+}