ast, parser, fmt: fix fmt error of generic fntype (#17814)

vlib/v/ast/ast.v

@@ -1225,13 +1225,14 @@ pub mut:
 
 pub struct FnTypeDecl {
 pub:
-	name     string
-	is_pub   bool
-	typ      Type
-	pos      token.Pos
-	type_pos token.Pos
-	comments []Comment
-	attrs    []Attr // attributes of type declaration
+	name          string
+	is_pub        bool
+	typ           Type
+	pos           token.Pos
+	type_pos      token.Pos
+	comments      []Comment
+	generic_types []Type
+	attrs         []Attr // attributes of type declaration
 }
 
 // TODO: handle this differently

vlib/v/fmt/fmt.v

@@ -1396,7 +1396,12 @@ pub fn (mut f Fmt) fn_type_decl(node ast.FnTypeDecl) {
 	fn_typ_info := typ_sym.info as ast.FnType
 	fn_info := fn_typ_info.func
 	fn_name := f.no_cur_mod(node.name)
-	f.write('type ${fn_name} = fn (')
+	mut generic_types_str := ''
+	if node.generic_types.len > 0 {
+		generic_names := node.generic_types.map(f.table.sym(it).name)
+		generic_types_str = '[${generic_names.join(', ')}]'
+	}
+	f.write('type ${fn_name}${generic_types_str} = fn (')
 	for i, arg in fn_info.params {
 		if arg.is_mut {
 			f.write(arg.typ.share().str() + ' ')
@@ -1775,7 +1780,11 @@ pub fn (mut f Fmt) call_expr(node ast.CallExpr) {
 		}
 	}
 	if node.mod == '' && node.name == '' {
-		f.write(node.left.str())
+		if node.left is ast.CallExpr {
+			f.expr(node.left)
+		} else {
+			f.write(node.left.str())
+		}
 	}
 	f.write_generic_call_if_require(node)
 	f.write('(')

vlib/v/fmt/tests/generics_fntype_keep.vv

@@ -0,0 +1,24 @@
+type Fn[T] = fn (T)
+
+type FnReturn[T, R] = fn (T) R
+
+fn func_fn_concrete() Fn[string] {
+	return fn (_s string) {}
+}
+
+fn func_fn_dynamic[T]() Fn[T] {
+	return fn [T](_t T) {}
+}
+
+fn func_fn_return_dynamic[T, R]() FnReturn[T, R] {
+	return fn [T, R](t T) R {
+		return t.int()
+	}
+}
+
+fn main() {
+	func_fn_concrete()('V')
+	func_fn_dynamic[string]()('V')
+
+	assert func_fn_return_dynamic[string, int]()('100') == 100
+}

vlib/v/parser/parser.v

@@ -4016,6 +4016,7 @@ fn (mut p Parser) type_decl() ast.TypeDecl {
 			pos: decl_pos
 			type_pos: type_pos
 			comments: comments
+			generic_types: generic_types
 			attrs: attrs
 		}
 	}

vlib/v/tests/call_on_anon_test.v

@@ -29,16 +29,16 @@ fn f5(s string) fn (string) !string {
 }
 
 fn test_call_nested_anon() {
-	println(main.f1('V')('Lang')!)
-	s1 := main.f1('V')('Lang')!
+	println(f1('V')('Lang')!)
+	s1 := f1('V')('Lang')!
 	println(s1)
-	s2 := main.f1('V')('Lang') or { 'ErrLang' }
+	s2 := f1('V')('Lang') or { 'ErrLang' }
 	println(s2)
-	s3 := main.f2('V')('Lang')?
+	s3 := f2('V')('Lang')?
 	println(s3)
-	s4 := main.f2('V')('Lang') or { 'NoneLang' }
+	s4 := f2('V')('Lang') or { 'NoneLang' }
 	println(s4)
-	s := main.f3('V')('Lang')
+	s := f3('V')('Lang')
 	println(s)
 	assert s == 'VLang'
 	assert s1 == 'VLang'
@@ -46,10 +46,10 @@ fn test_call_nested_anon() {
 	assert s3 == 'VLang'
 	assert s4 == 'VLang'
 
-	s5 := main.f4('V')('Lang') or { 'Lang++' }
+	s5 := f4('V')('Lang') or { 'Lang++' }
 	println(s5)
 	assert s5 == 'Lang++'
-	s6 := main.f5('V')('Lang') or { '${err}' }
+	s6 := f5('V')('Lang') or { '${err}' }
 	println(s6)
 	assert s6 == 'test'
 }

vlib/v/tests/const_name_equals_fn_name_test.v

@@ -39,7 +39,7 @@ fn test_a_const_that_is_alias_to_fn_from_module() {
 
 const pg = fn_generator()
 
-const pg2 = main.fn_generator()()
+const pg2 = fn_generator()()
 
 fn fn_generator() fn () string {
 	return fn () string {
@@ -49,7 +49,7 @@ fn fn_generator() fn () string {
 }
 
 fn test_a_const_can_be_assigned_a_fn_produced_by_a_fn_generator_and_the_const_can_be_used() {
-	assert main.fn_generator()() == 'ok'
+	assert fn_generator()() == 'ok'
 
 	x := fn_generator()
 	assert x() == 'ok'

vlib/v/tests/fn_call_using_anon_fn_call_args_test.v

@@ -11,9 +11,9 @@ fn foofun2(op string) fn () int {
 }
 
 fn test_fn_call_using_anon_fn_call_arg() {
-	println(main.foofun1('1')())
-	assert main.foofun1('1')() == 'x passed'
+	println(foofun1('1')())
+	assert foofun1('1')() == 'x passed'
 
-	println(main.foofun2('1')())
-	assert main.foofun2('1')() == 22
+	println(foofun2('1')())
+	assert foofun2('1')() == 22
 }

vlib/v/tests/match_return_fn_test.v

@@ -77,13 +77,13 @@ fn err5(f fn ()) fn () {
 }
 
 fn test_main() {
-	var := main.err()()
+	var := err()()
 	assert var == 'b'
 
-	var2 := main.err2()()
+	var2 := err2()()
 	assert var2 == 'a'
 
-	var3 := main.err3()()
+	var3 := err3()()
 	assert var3 == 'c'
 
 	var4 := err4()

vlib/v/tests/sumtype_with_alias_fntype_fn_call_test.v

@@ -30,7 +30,7 @@ fn run(mmff Maybefnfact) string {
 }
 
 fn test_sumtype_with_alias_fntype_fn_call() {
-	r1 := main.myfnfact()(1)
+	r1 := myfnfact()(1)
 	println(r1)
 	assert r1 == 1
 

vlib/v/tests/sumtype_with_alias_fntype_test.v

@@ -23,7 +23,7 @@ fn test_sumtype_with_alias_fntype() {
 	myfnfact := fn () Myfn {
 		return abc
 	}
-	r1 := main.myfnfact()(1)
+	r1 := myfnfact()(1)
 	println(r1)
 	assert r1 == 1