parser: experimental syntax that doesn't require an extra indent

vlib/v/ast/ast.v

@@ -1267,6 +1267,7 @@ pub mut:
 	cond_type     Type // type of `x` in `match x {`
 	expected_type Type // for debugging only
 	is_sum_type   bool
+	no_lcbr       bool // for match statements without {}
 }
 
 pub struct MatchBranch {

vlib/v/fmt/fmt.v

@@ -2858,8 +2858,12 @@ fn (mut f Fmt) match_branch(branch ast.MatchBranch, single_line bool) {
 pub fn (mut f Fmt) match_expr(node ast.MatchExpr) {
 	f.write('match ')
 	f.expr(node.cond)
-	f.writeln(' {')
-	f.indent++
+	if node.no_lcbr {
+		f.writeln('')
+	} else {
+		f.writeln(' {')
+		f.indent++
+	}
 	f.comments(node.comments)
 	mut single_line := true
 	for branch in node.branches {
@@ -2886,8 +2890,10 @@ pub fn (mut f Fmt) match_expr(node ast.MatchExpr) {
 	if else_idx >= 0 {
 		f.match_branch(node.branches[else_idx], single_line)
 	}
-	f.indent--
-	f.write('}')
+	if !node.no_lcbr {
+		f.indent--
+		f.write('}')
+	}
 }
 
 pub fn (mut f Fmt) offset_of(node ast.OffsetOf) {

vlib/v/parser/if_match.v

@@ -375,7 +375,7 @@ fn (mut p Parser) match_expr() ast.MatchExpr {
 		len:     match_last_pos.pos - match_first_pos.pos + match_last_pos.len
 		col:     match_first_pos.col
 	}
-	if p.tok.kind == .rcbr {
+	if p.tok.kind == .rcbr && !no_lcbr {
 		p.check(.rcbr)
 	}
 	// return ast.StructInit{}
@@ -386,6 +386,7 @@ fn (mut p Parser) match_expr() ast.MatchExpr {
 		is_sum_type: is_sum_type
 		pos:         pos
 		comments:    comments
+		no_lcbr:     no_lcbr
 	}
 }
 

vlib/v/tests/options/option_match_test.v

@@ -1,35 +1,32 @@
 fn test_simple_match_expr() {
 	mut a := ?int(12)
-	match a? {
-		12 {
-			println(a)
-		}
-		else {
-			println('else')
-			assert false
-		}
+	match a?
+	12 {
+		println(a)
+	}
+	else {
+		println('else')
+		assert false
 	}
 
-	match a {
-		none {
-			println('none')
-			assert false
-		}
-		else {
-			println('else')
-		}
+	match a
+	none {
+		println('none')
+		assert false
+	}
+	else {
+		println('else')
 	}
 
 	a = none
 
-	match a {
-		none {
-			println('none')
-		}
-		else {
-			println('else')
-			assert false
-		}
+	match a
+	none {
+		println('none')
+	}
+	else {
+		println('else')
+		assert false
 	}
 
 	mut b := ?string('aaa')
@@ -43,24 +40,23 @@ fn test_simple_match_expr() {
 		}
 	}
 
-	match b {
-		none {
-			println('none')
-			assert false
-		}
-		else {
-			println('else')
-		}
+	match b
+	none {
+		println('none')
+		assert false
+	}
+	else {
+		println('else')
 	}
 
 	b = none
-	match b {
-		none {
-			println('none')
-		}
-		else {
-			println('else')
-			assert false
-		}
+	match b
+	none {
+		println('none')
 	}
+	else {
+		println('else')
+		assert false
+	}
+
 }