checker: fix "unnecessary `()`" error position

vlib/v/checker/checker.v

@@ -1630,12 +1630,8 @@ pub fn (c mut Checker) if_expr(node mut ast.IfExpr) table.Type {
 	}
 	node.typ = table.void_type
 	for i, branch in node.branches {
-		match branch.cond {
-			ast.ParExpr {
-				c.error('unnecessary `()` in an if condition. use `if expr {` instead of `if (expr) {`.',
-					node.pos)
-			}
-			else {}
+		if branch.cond is ast.ParExpr {
+			c.error('unnecessary `()` in an if condition. use `if expr {` instead of `if (expr) {`.', branch.pos)
 		}
 		typ := c.expr(branch.cond)
 		if i < node.branches.len - 1 || !node.has_else {

vlib/v/checker/tests/inout/unnecessary_parenthesis.out

@@ -0,0 +1,20 @@
+vlib/v/checker/tests/inout/unnecessary_parenthesis.v:2:2: error: unnecessary `()` in an if condition. use `if expr {` instead of `if (expr) {`.
+    1| fn main() {
+    2|     if (1 == 1) {
+           ~~~~~~~~~~~
+    3|         println('yeay')
+    4|     } else if (1 == 2) {
+vlib/v/checker/tests/inout/unnecessary_parenthesis.v:4:4: error: unnecessary `()` in an if condition. use `if expr {` instead of `if (expr) {`.
+    2|     if (1 == 1) {
+    3|         println('yeay')
+    4|     } else if (1 == 2) {
+             ~~~~~~~~~~~~~~~~
+    5|         println("oh no :'(")
+    6|     } else if (1 == 3) {
+vlib/v/checker/tests/inout/unnecessary_parenthesis.v:6:4: error: unnecessary `()` in an if condition. use `if expr {` instead of `if (expr) {`.
+    4|     } else if (1 == 2) {
+    5|         println("oh no :'(")
+    6|     } else if (1 == 3) {
+             ~~~~~~~~~~~~~~~~
+    7|         println("what's wrong with physics ????")
+    8|     }

vlib/v/checker/tests/inout/unnecessary_parenthesis.vv

@@ -0,0 +1,9 @@
+fn main() {
+	if (1 == 1) {
+		println('yeay')
+	} else if (1 == 2) {
+		println("oh no :'(")
+	} else if (1 == 3) {
+		println("what's wrong with physics ????")
+	}
+}

vlib/v/parser/if.v

@@ -13,7 +13,7 @@ fn (mut p Parser) if_expr() ast.IfExpr {
 	mut has_else := false
 	for p.tok.kind in [.key_if, .key_else] {
 		p.inside_if = true
-		branch_pos := p.tok.position()
+		start_pos := p.tok.position()
 		mut comment := ast.Comment{}
 		if p.tok.kind == .key_if {
 			p.check(.key_if)
@@ -28,9 +28,10 @@ fn (mut p Parser) if_expr() ast.IfExpr {
 			} else {
 				has_else = true
 				p.inside_if = false
+				end_pos := p.prev_tok.position()
 				branches << ast.IfBranch{
 					stmts: p.parse_block()
-					pos: branch_pos
+					pos: start_pos.extend(end_pos)
 					comment: comment
 				}
 				break
@@ -56,6 +57,7 @@ fn (mut p Parser) if_expr() ast.IfExpr {
 		} else {
 			cond = p.expr(0)
 		}
+		end_pos := p.prev_tok.position()
 		p.inside_if = false
 		stmts := p.parse_block()
 		if is_or {
@@ -64,7 +66,7 @@ fn (mut p Parser) if_expr() ast.IfExpr {
 		branches << ast.IfBranch{
 			cond: cond
 			stmts: stmts
-			pos: branch_pos
+			pos: start_pos.extend(end_pos)
 			comment: ast.Comment{}
 		}
 		if p.tok.kind != .key_else {