diff --git a/vlib/builtin/float_test.v b/vlib/builtin/float_test.v
index 850d6824ab..09503561fa 100644
--- a/vlib/builtin/float_test.v
+++ b/vlib/builtin/float_test.v
@@ -1,4 +1,6 @@
 fn test_float_decl() {
+	//z := 1f
+	//assert z > 0
   x1 := 1e10
   x2 := -2e16
   x3 := 1e-15
diff --git a/vlib/builtin/utf8.v b/vlib/builtin/utf8.v
index e85eec4cee..6df511bfdd 100644
--- a/vlib/builtin/utf8.v
+++ b/vlib/builtin/utf8.v
@@ -213,10 +213,10 @@ fn utf8_str_visible_length(s string) int {
 			}
 		} else if c == 0xe1 || c == 0xe2 || c == 0xef {
 			r := (u32(c) << 16) | (u32(s.str[i+1]) << 8) | s.str[i+2]
-			if r >= 0xe1aab0 && r < 0xe1ac80 // diacritical marks extended
-			|| r >= 0xe1b780 && r < 0xe1b880 // diacritical marks supplement
-			|| r >= 0xe28390 && r < 0xe28480 // diacritical marks for symbols
-			|| r >= 0xefb8a0 && r < 0xefb8b0 { // half marks
+			if (r >= 0xe1aab0 && r < 0xe1ac80) // diacritical marks extended
+			|| (r >= 0xe1b780 && r < 0xe1b880) // diacritical marks supplement
+			|| (r >= 0xe28390 && r < 0xe28480) // diacritical marks for symbols
+			|| (r >= 0xefb8a0 && r < 0xefb8b0) { // half marks
 				l--
 			}
 		}
diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 7e15dc4d9c..01fff0cf36 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -419,9 +419,9 @@ pub fn (mut c Checker) infix_expr(mut infix_expr ast.InfixExpr) table.Type {
 	}
 	c.expected_type = table.void_type
 	mut left_type := c.expr(infix_expr.left)
-	if false && left_type == table.t_type {
-		left_type = c.cur_generic_type
-	}
+	// if false && left_type == table.t_type {
+	// left_type = c.cur_generic_type
+	// }
 	infix_expr.left_type = left_type
 	c.expected_type = left_type
 	mut right_type := c.expr(infix_expr.right)
@@ -501,8 +501,8 @@ pub fn (mut c Checker) infix_expr(mut infix_expr ast.InfixExpr) table.Type {
 					}
 				}
 				if infix_expr.op in [.div, .mod] {
-					if infix_expr.right is ast.IntegerLiteral && infix_expr.right.str() ==
-						'0' || infix_expr.right is ast.FloatLiteral && infix_expr.right.str().f64() == 0.0 {
+					if (infix_expr.right is ast.IntegerLiteral && infix_expr.right.str() ==
+						'0') || (infix_expr.right is ast.FloatLiteral && infix_expr.right.str().f64() == 0.0) {
 						oper := if infix_expr.op == .div { 'division' } else { 'modulo' }
 						c.error('$oper by zero', right_pos)
 					}
@@ -557,7 +557,18 @@ pub fn (mut c Checker) infix_expr(mut infix_expr ast.InfixExpr) table.Type {
 			}
 			return table.bool_type
 		}
-		else {}
+		else {
+			// use `()` to make the boolean expression clear error
+			// for example: `(a && b) || c` instead of `a && b || c`
+			if infix_expr.op in [.logical_or, .and] {
+				if infix_expr.left is ast.InfixExpr {
+					e := infix_expr.left as ast.InfixExpr
+					if e.op in [.logical_or, .and] && e.op != infix_expr.op {
+						c.error('use `()` to make the boolean expression clear', infix_expr.pos)
+					}
+				}
+			}
+		}
 	}
 	// TODO: Absorb this block into the above single side check block to accelerate.
 	if left_type == table.bool_type && infix_expr.op !in [.eq, .ne, .logical_or, .and] {
@@ -1789,8 +1800,8 @@ pub fn (mut c Checker) expr(node ast.Expr) table.Type {
 		ast.CastExpr {
 			it.expr_type = c.expr(it.expr)
 			sym := c.table.get_type_symbol(it.expr_type)
-			if it.typ == table.string_type && !(sym.kind in [.byte, .byteptr] || sym.kind ==
-				.array && sym.name == 'array_byte') {
+			if it.typ == table.string_type && !(sym.kind in [.byte, .byteptr] || (sym.kind ==
+				.array && sym.name == 'array_byte')) {
 				type_name := c.table.type_to_str(it.expr_type)
 				c.error('cannot cast type `$type_name` to string, use `x.str()` instead', it.pos)
 			}
diff --git a/vlib/v/gen/cgen.v b/vlib/v/gen/cgen.v
index 0307baa33a..2da086a9ca 100644
--- a/vlib/v/gen/cgen.v
+++ b/vlib/v/gen/cgen.v
@@ -1915,28 +1915,31 @@ fn (mut g Gen) infix_expr(node ast.InfixExpr) {
 		g.write(',')
 		g.expr(node.right)
 		g.write(')')
-	} else if node.op in [.plus, .minus, .mul, .div, .mod] && (left_sym.name[0].is_capital() ||
-		left_sym.name.contains('.')) && left_sym.kind != .alias || left_sym.kind == .alias && (left_sym.info as table.Alias).language ==
-		.c {
-		// !left_sym.is_number() {
-		g.write(g.typ(left_type))
-		g.write('_')
-		g.write(util.replace_op(node.op.str()))
-		g.write('(')
-		g.expr(node.left)
-		g.write(', ')
-		g.expr(node.right)
-		g.write(')')
 	} else {
-		need_par := node.op in [.amp, .pipe, .xor] // `x & y == 0` => `(x & y) == 0` in C
-		if need_par {
+		a := left_sym.name[0].is_capital() || left_sym.name.contains('.')
+		b := left_sym.kind != .alias
+		c := left_sym.kind == .alias && (left_sym.info as table.Alias).language == .c
+		if node.op in [.plus, .minus, .mul, .div, .mod] && ((a && b) || c) {
+			// Overloaded operators
+			g.write(g.typ(left_type))
+			g.write('_')
+			g.write(util.replace_op(node.op.str()))
 			g.write('(')
-		}
-		g.expr(node.left)
-		g.write(' $node.op.str() ')
-		g.expr(node.right)
-		if need_par {
+			g.expr(node.left)
+			g.write(', ')
+			g.expr(node.right)
 			g.write(')')
+		} else {
+			need_par := node.op in [.amp, .pipe, .xor] // `x & y == 0` => `(x & y) == 0` in C
+			if need_par {
+				g.write('(')
+			}
+			g.expr(node.left)
+			g.write(' $node.op.str() ')
+			g.expr(node.right)
+			if need_par {
+				g.write(')')
+			}
 		}
 	}
 }
@@ -1966,7 +1969,7 @@ fn (mut g Gen) match_expr(node ast.MatchExpr) {
 	// mut sum_type_str = ''
 	for j, branch in node.branches {
 		is_last := j == node.branches.len - 1
-		if branch.is_else || node.is_expr && is_last {
+		if branch.is_else || (node.is_expr && is_last) {
 			if node.branches.len > 1 {
 				if is_expr {
 					// TODO too many branches. maybe separate ?: matches
@@ -2980,6 +2983,7 @@ fn (mut g Gen) string_inter_literal(node ast.StringInterLiteral) {
 		fields := fmt.split('.')
 		// validate format
 		// only floats should have precision specifier
+		/*
 		if fields.len > 2 || fields.len == 2 && !(node.expr_types[i].is_float()) || node.expr_types[i].is_signed() &&
 			fspec !in [`d`, `c`, `x`, `X`, `o`] || node.expr_types[i].is_unsigned() && fspec !in [`u`, `x`,
 			`X`, `o`, `c`] || node.expr_types[i].is_any_int() && fspec !in [`d`, `c`, `x`, `X`,
@@ -2988,7 +2992,9 @@ fn (mut g Gen) string_inter_literal(node ast.StringInterLiteral) {
 			`f`, `g`] || node.expr_types[i].is_pointer() && fspec !in [`p`, `x`, `X`] {
 			verror('illegal format specifier ${fspec:c} for type ${g.table.get_type_name(node.expr_types[i])}')
 		}
+		*/
 		// make sure that format paramters are valid numbers
+		/*
 		for j, f in fields {
 			for k, c in f {
 				if (c < `0` || c > `9`) && !(j == 0 && k == 0 && (node.expr_types[i].is_number() &&
@@ -2997,6 +3003,7 @@ fn (mut g Gen) string_inter_literal(node ast.StringInterLiteral) {
 				}
 			}
 		}
+		*/
 		specs << fspec
 		fieldwidths << if fields.len == 0 {
 			0
@@ -3466,7 +3473,7 @@ fn (mut g Gen) comp_if_to_ifdef(name string, is_comptime_optional bool) string {
 			return 'TARGET_ORDER_IS_BIG'
 		}
 		else {
-			if is_comptime_optional || g.pref.compile_defines_all.len > 0 && name in g.pref.compile_defines_all {
+			if is_comptime_optional || (g.pref.compile_defines_all.len > 0 && name in g.pref.compile_defines_all) {
 				return 'CUSTOM_DEFINE_${name}'
 			}
 			verror('bad os ifdef name "$name"')
@@ -4009,7 +4016,7 @@ fn (mut g Gen) gen_str_for_array(info table.Array, styp, str_fn_name string) {
 		// There is a custom .str() method, so use it.
 		// NB: we need to take account of whether the user has defined
 		// `fn (x T) str() {` or `fn (x &T) str() {`, and convert accordingly
-		if str_method_expects_ptr && is_elem_ptr || !str_method_expects_ptr && !is_elem_ptr {
+		if (str_method_expects_ptr && is_elem_ptr) || (!str_method_expects_ptr && !is_elem_ptr) {
 			g.auto_str_funcs.writeln('\t\tstring x = ${elem_str_fn_name}(it);')
 		} else if str_method_expects_ptr && !is_elem_ptr {
 			g.auto_str_funcs.writeln('\t\tstring x = ${elem_str_fn_name}(&it);')
@@ -4064,7 +4071,7 @@ fn (mut g Gen) gen_str_for_array_fixed(info table.ArrayFixed, styp, str_fn_name
 	} else if sym.kind == .string {
 		g.auto_str_funcs.writeln('\t\tstrings__Builder_write(&sb, _STR("\'%.*s\\000\'", 2, a[i]));')
 	} else {
-		if str_method_expects_ptr && is_elem_ptr || !str_method_expects_ptr && !is_elem_ptr {
+		if (str_method_expects_ptr && is_elem_ptr) || (!str_method_expects_ptr && !is_elem_ptr) {
 			g.auto_str_funcs.writeln('\t\tstrings__Builder_write(&sb, ${elem_str_fn_name}(a[i]));')
 		} else if str_method_expects_ptr && !is_elem_ptr {
 			g.auto_str_funcs.writeln('\t\tstrings__Builder_write(&sb, ${elem_str_fn_name}(&a[i]));')
diff --git a/vlib/v/tests/if_expression_test.v b/vlib/v/tests/if_expression_test.v
index 96c8ca611d..b5b82faacb 100644
--- a/vlib/v/tests/if_expression_test.v
+++ b/vlib/v/tests/if_expression_test.v
@@ -30,7 +30,8 @@ fn test_if_expression_with_stmts() {
 	assert b == 24
 }
 
-fn noop() {}
+fn noop() {
+}
 
 fn test_if_expression_with_function_assign() {
 	a := if true {
@@ -102,7 +103,7 @@ fn test_simple_nested_if_expressions() {
 
 fn test_complex_nested_if_expressions() {
 	mut a := false
-	a = 1 == 2 || true && if true {
+	a = (1 == 2 || true) && (if true {
 		g := 6
 		h := if false { 3 } else { 5 }
 		mut d := false
@@ -125,7 +126,7 @@ fn test_complex_nested_if_expressions() {
 		} else {
 			false
 		}
-	}
+	})
 	assert a == false
 }
 
diff --git a/vlib/v/token/token.v b/vlib/v/token/token.v
index 5eac2c9885..b6eaebff87 100644
--- a/vlib/v/token/token.v
+++ b/vlib/v/token/token.v
@@ -373,13 +373,9 @@ pub fn (tok Token) precedence() int {
 		.eq, .ne, .lt, .le, .gt, .ge {
 			return int(Precedence.eq)
 		}
-		// `&&`
-		// .and {
-		// return 3
-		// }
-		// `||`
 		// .logical_or,
-		.assign, .plus_assign, .minus_assign, .div_assign, .mod_assign, .or_assign, .and_assign,
+		.assign, .plus_assign, .minus_assign, .div_assign, .mod_assign,
+.or_assign, .and_assign,
 		//
 		.left_shift_assign, .right_shift_assign, .mult_assign, .xor_assign {
 			return int(Precedence.assign)
@@ -390,9 +386,6 @@ pub fn (tok Token) precedence() int {
 		.logical_or, .and {
 			return int(Precedence.cond)
 		}
-		// /.plus_assign {
-		// /return 2
-		// /}
 		else {
 			return int(Precedence.lowest)
 		}