ast, cgen: implement sumtype with fntype partly (related #15557) (#15567)

vlib/v/ast/table.v

@@ -1195,7 +1195,7 @@ pub fn (mut t Table) find_or_register_fn_type(f Fn, is_anon bool, has_decl bool)
 	cname := if f.name.len == 0 {
 		'anon_fn_${t.fn_type_signature(f)}'
 	} else {
-		util.no_dots(f.name.clone())
+		util.no_dots(f.name.clone()).replace_each([' ', '', '(', '_', ')', ''])
 	}
 	anon := f.name.len == 0 || is_anon
 	existing_idx := t.type_idxs[name]
@@ -1295,6 +1295,9 @@ pub fn (t &Table) sumtype_has_variant(parent Type, variant Type, is_as bool) boo
 			.alias {
 				return t.sumtype_check_alias_variant(parent, variant, is_as)
 			}
+			.function {
+				return t.sumtype_check_function_variant(parent_info, variant, is_as)
+			}
 			else {
 				return t.sumtype_check_variant_in_type(parent_info, variant, is_as)
 			}
@@ -1303,6 +1306,15 @@ pub fn (t &Table) sumtype_has_variant(parent Type, variant Type, is_as bool) boo
 	return false
 }
 
+fn (t &Table) sumtype_check_function_variant(parent_info SumType, variant Type, is_as bool) bool {
+	for v in parent_info.variants {
+		if '$v.idx' == '$variant.idx' && (!is_as || v.nr_muls() == variant.nr_muls()) {
+			return true
+		}
+	}
+	return false
+}
+
 fn (t &Table) sumtype_check_variant_in_type(parent_info SumType, variant Type, is_as bool) bool {
 	for v in parent_info.variants {
 		if v.idx() == variant.idx() && (!is_as || v.nr_muls() == variant.nr_muls()) {

vlib/v/gen/c/cgen.v

@@ -2102,7 +2102,12 @@ fn (mut g Gen) get_sumtype_casting_fn(got_ ast.Type, exp_ ast.Type) string {
 fn (mut g Gen) write_sumtype_casting_fn(fun SumtypeCastingFn) {
 	got, exp := fun.got, fun.exp
 	got_sym, exp_sym := g.table.sym(got), g.table.sym(exp)
-	got_cname, exp_cname := got_sym.cname, exp_sym.cname
+	mut got_cname, exp_cname := got_sym.cname, exp_sym.cname
+	if got_sym.info is ast.FnType {
+		if got_sym.info.is_anon {
+			got_cname = 'anon_fn_${g.table.fn_type_signature(got_sym.info.func)}'
+		}
+	}
 	mut sb := strings.new_builder(128)
 	sb.writeln('static inline $exp_cname ${fun.fn_name}($got_cname* x) {')
 	sb.writeln('\t$got_cname* ptr = memdup(x, sizeof($got_cname));')
@@ -2231,7 +2236,12 @@ fn (mut g Gen) expr_with_cast(expr ast.Expr, got_type_raw ast.Type, expected_typ
 	}
 	// cast to sum type
 	exp_styp := g.typ(expected_type)
-	got_styp := g.typ(got_type)
+	mut got_styp := g.typ(got_type)
+	if got_sym.info is ast.FnType {
+		if got_sym.info.is_anon {
+			got_styp = 'anon_fn_${g.table.fn_type_signature(got_sym.info.func)}'
+		}
+	}
 	if expected_type != ast.void_type {
 		unwrapped_expected_type := g.unwrap_generic(expected_type)
 		unwrapped_exp_sym := g.table.sym(unwrapped_expected_type)

vlib/v/tests/inout/sumtype_with_fntype.out

@@ -0,0 +1 @@
+Fns

vlib/v/tests/inout/sumtype_with_fntype.vv

@@ -0,0 +1,8 @@
+type Fns = bool | fn (int) int
+
+fn main() {
+	f := Fns(fn (a int) int {
+		return a
+	})
+	println(typeof(f).name)
+}