parser: report unused expression error in if and or blocks (#6953)

vlib/regex/regex.v

@@ -1650,7 +1650,7 @@ pub fn (mut re RE) match_base(in_txt byteptr, in_txt_len int ) (int,int) {
 
 			// manage ist_dot_char
 
-			m_state == .end
+			m_state = .end
 			break
 			//return no_match_found,0
 		}
@@ -1822,7 +1822,7 @@ pub fn (mut re RE) match_base(in_txt byteptr, in_txt_len int ) (int,int) {
 					//println("ist_or_branch False pc: $pc")
 				}
 				re.prog[pc].reset()
-				m_state == .ist_load
+				m_state = .ist_load
 				continue
 			}
 

vlib/v/parser/parser.v

@@ -886,10 +886,10 @@ fn (mut p Parser) parse_multi_expr(is_top_level bool) ast.Stmt {
 	}
 	if p.tok.kind in [.assign, .decl_assign] || p.tok.kind.is_assign() {
 		return p.partial_assign_stmt(left, left_comments)
-	} else if is_top_level && tok.kind !in
+	} else if tok.kind !in [.key_if, .key_match, .key_lock, .key_rlock, .key_select] &&
-		[.key_if, .key_match, .key_lock, .key_rlock, .key_select] && left0 !is ast.CallExpr &&
+		left0 !is ast.CallExpr && (is_top_level || p.tok.kind != .rcbr) && left0 !is ast.PostfixExpr &&
-		left0 !is ast.PostfixExpr && !(left0 is ast.InfixExpr &&
+		!(left0 is ast.InfixExpr && (left0 as ast.InfixExpr).op in [.left_shift, .arrow]) && left0 !is
-		(left0 as ast.InfixExpr).op in [.left_shift, .arrow]) && left0 !is ast.ComptimeCall {
+		ast.ComptimeCall {
 		p.error_with_pos('expression evaluated but not used', left0.position())
 	}
 	if left.len == 1 {

vlib/v/parser/tests/expr_evaluated_but_not_used_if.out

@@ -0,0 +1,7 @@
+vlib/v/parser/tests/expr_evaluated_but_not_used_if.vv:3:5: error: expression evaluated but not used
+    1 | fn main() {
+    2 |   if true {
+    3 |     1 + 1
+      |     ~~~~~
+    4 |     1 + 1
+    5 |   } else {

vlib/v/parser/tests/expr_evaluated_but_not_used_if.vv

@@ -0,0 +1,8 @@
+fn main() {
+  if true {
+    1 + 1
+    1 + 1
+  } else {
+    1 + 1
+  }
+}

vlib/v/parser/tests/expr_evaluated_but_not_used_or.out

@@ -0,0 +1,7 @@
+vlib/v/parser/tests/expr_evaluated_but_not_used_or.vv:3:5: error: expression evaluated but not used
+    1 | fn main() {
+    2 |   f() or {
+    3 |     0
+      |     ^
+    4 |     1
+    5 |   }

vlib/v/parser/tests/expr_evaluated_but_not_used_or.vv

@@ -0,0 +1,10 @@
+fn main() {
+  f() or {
+    0
+    1
+  }
+}
+
+fn f() ?int {
+  return none
+}

vlib/x/json2/decoder.v

@@ -128,7 +128,7 @@ fn (p Parser) is_singlequote() bool {
 fn (mut p Parser) detect_parse_mode() {
 	src := p.scanner.text
 	if src.len > 1 && src[0].is_digit() && !src[1].is_digit() {
-		p.mode == .invalid
+		p.mode = .invalid
 		return
 	}
 
@@ -136,7 +136,7 @@ fn (mut p Parser) detect_parse_mode() {
 	p.n_tok = p.scanner.scan()
 
 	if src.len == 1 && p.tok.kind == .string && p.n_tok.kind == .eof {
-		p.mode == .invalid
+		p.mode = .invalid
 		return
 	}