vfmt: support `struct Repo <T, U> { }`

cmd/tools/vtest-fmt.v

@@ -7,7 +7,6 @@ import v.util
 // os.v - // embeded comments, mib := [1/* CTL_KERN */, 14/* KERN_PROC */, 12/* KERN_PROC_PATHNAME */, -1] => comment the rest of the line
 const (
 	known_failing_exceptions = [
-		'vlib/v/tests/generics_test.v', // struct Repo<T, U> { => struct Repo {
 		'vlib/crypto/aes/aes.v', // pub fn (c &AesCipher) encrypt(mut dst, mut src []byte) {
 		'vlib/crypto/aes/block_generic.v', // fn expand_key_generic(key []byte, mut enc, mut dec []u32) {
 		'vlib/crypto/aes/const.v', // multiple narrow columns of []string turned to 1 long single column, otherwise works

vlib/v/ast/ast.v

@@ -170,6 +170,7 @@ pub struct StructDecl {
 pub:
 	pos          token.Position
 	name         string
+	gen_types    []table.Type
 	is_pub       bool
 	mut_pos      int // mut:
 	pub_pos      int // pub:

vlib/v/fmt/fmt.v

@@ -599,7 +599,14 @@ pub fn (mut f Fmt) struct_decl(node ast.StructDecl) {
 	}
 	f.write_language_prefix(node.language)
 	name := node.name.after('.')
-	f.writeln('$name {')
+	f.write(name)
+	if node.gen_types.len > 0 {
+		f.write(' <')
+		gtypes := node.gen_types.map(f.table.type_to_str(it)).join(', ')
+		f.write(gtypes)
+		f.write('>')
+	}
+	f.writeln(' {')
 	mut max := 0
 	mut max_type := 0
 	mut field_types := []string{cap: node.fields.len}

vlib/v/fmt/tests/generic_structs_keep.vv

@@ -0,0 +1,28 @@
+struct Foo <T> {
+pub:
+	data T
+}
+
+fn (f Foo<int>) value() string {
+	return f.data.str()
+}
+
+type DB = string
+
+struct Repo <T, U> {
+	db         DB
+pub mut:
+	model      T
+	permission U
+}
+
+fn main() {
+	foo_int := Foo<int>{2}
+	assert foo_int.value() == '2'
+	println(foo_int)
+	//
+	x := Repo<int,f64>{'abc', 3, 1.5}
+	println(x.db)
+	println(x.model)
+	println(x.permission)
+}

vlib/v/parser/struct.v

@@ -287,6 +287,7 @@ fn (mut p Parser) struct_decl() ast.StructDecl {
 		is_union: is_union
 		attrs: attrs
 		end_comments: end_comments
+		gen_types: generic_types
 	}
 }