checker, ast: add field promoted_type for InfixExpr, filled in by the checker, to save duplicate work in the backends (#17158)

cmd/tools/vast/vast.v

@@ -1350,6 +1350,7 @@ fn (t Tree) infix_expr(node ast.InfixExpr) &Node {
 	obj.add_terse('left_type', t.type_node(node.left_type))
 	obj.add_terse('right', t.expr(node.right))
 	obj.add_terse('right_type', t.type_node(node.right_type))
+	obj.add_terse('promoted_type', t.type_node(node.promoted_type))
 	obj.add('auto_locked', t.string_node(node.auto_locked))
 	obj.add_terse('or_block', t.or_expr(node.or_block))
 	obj.add_terse('is_stmt', t.bool_node(node.is_stmt))

vlib/v/ast/ast.v

@@ -866,12 +866,13 @@ pub:
 	pos     token.Pos
 	is_stmt bool
 pub mut:
-	left        Expr
-	right       Expr
-	left_type   Type
-	right_type  Type
-	auto_locked string
-	or_block    OrExpr
+	left          Expr
+	right         Expr
+	left_type     Type
+	right_type    Type
+	promoted_type Type = void_type
+	auto_locked   string
+	or_block      OrExpr
 	//
 	ct_left_value_evaled  bool
 	ct_left_value         ComptTimeConstValue = empty_comptime_const_expr()

vlib/v/checker/infix.v

@@ -23,6 +23,7 @@ fn (mut c Checker) infix_expr(mut node ast.InfixExpr) ast.Type {
 	if node.op == .amp && left_type.is_bool() && right_type.is_bool() && right_type.is_ptr() {
 		pos := node.pos.extend(node.right.pos())
 		c.error('the right expression should be separated from the `&&` by a space', pos)
+		node.promoted_type = ast.bool_type
 		return ast.bool_type
 	}
 	node.right_type = right_type
@@ -188,6 +189,7 @@ fn (mut c Checker) infix_expr(mut node ast.InfixExpr) ast.Type {
 						node.pos)
 				}
 			}
+			node.promoted_type = ast.bool_type
 			return ast.bool_type
 		}
 		.plus, .minus, .mul, .div, .mod, .xor, .amp, .pipe {
@@ -367,6 +369,7 @@ fn (mut c Checker) infix_expr(mut node ast.InfixExpr) ast.Type {
 				c.error('only `==` and `!=` are defined on arrays', node.pos)
 			} else if left_sym.kind == .struct_
 				&& (left_sym.info as ast.Struct).generic_types.len > 0 {
+				node.promoted_type = ast.bool_type
 				return ast.bool_type
 			} else if left_sym.kind == .struct_ && right_sym.kind == .struct_
 				&& node.op in [.eq, .lt] {
@@ -489,11 +492,13 @@ fn (mut c Checker) infix_expr(mut node ast.InfixExpr) ast.Type {
 				c.error('cannot append `${right_sym.name}` to `${left_sym.name}`', right_pos)
 				return ast.void_type
 			} else {
-				return c.check_shift(mut node, left_type, right_type)
+				node.promoted_type = c.check_shift(mut node, left_type, right_type)
+				return node.promoted_type
 			}
 		}
 		.right_shift {
-			return c.check_shift(mut node, left_type, right_type)
+			node.promoted_type = c.check_shift(mut node, left_type, right_type)
+			return node.promoted_type
 		}
 		.unsigned_right_shift {
 			modified_left_type := if !left_type.is_int() {
@@ -538,7 +543,9 @@ fn (mut c Checker) infix_expr(mut node ast.InfixExpr) ast.Type {
 				or_block: node.or_block
 			}
 
-			return c.check_shift(mut node, left_type, right_type)
+			node.promoted_type = c.check_shift(mut node, left_type, right_type)
+
+			return node.promoted_type
 		}
 		.key_is, .not_is {
 			right_expr := node.right
@@ -579,6 +586,7 @@ fn (mut c Checker) infix_expr(mut node ast.InfixExpr) ast.Type {
 					}
 				}
 			}
+			node.promoted_type = ast.bool_type
 			return ast.bool_type
 		}
 		.arrow { // `chan <- elem`
@@ -677,6 +685,7 @@ fn (mut c Checker) infix_expr(mut node ast.InfixExpr) ast.Type {
 			}
 			if left_type.nr_muls() > 0 && right_type.is_int() {
 				// pointer arithmetic is fine, it is checked in other places
+				node.promoted_type = return_type
 				return return_type
 			}
 			c.error('infix expr: cannot use `${right_sym.name}` (right expression) as `${left_sym.name}`',
@@ -698,7 +707,8 @@ fn (mut c Checker) infix_expr(mut node ast.InfixExpr) ast.Type {
 		c.warn('`++` and `--` are statements, not expressions', node.pos)
 	}
 	*/
-	return if node.op.is_relational() { ast.bool_type } else { return_type }
+	node.promoted_type = if node.op.is_relational() { ast.bool_type } else { return_type }
+	return node.promoted_type
 }
 
 fn (mut c Checker) check_div_mod_by_zero(expr ast.Expr, op_kind token.Kind) {