cgen: fix if cond with result or optional in infix expr (#16625)

vlib/v/gen/c/fn.v

@@ -688,8 +688,15 @@ fn (mut g Gen) call_expr(node ast.CallExpr) {
 		if gen_or && !is_gen_or_and_assign_rhs {
 			cur_line = g.go_before_stmt(0)
 		}
+		if gen_or && g.infix_left_var_name.len > 0 {
+			g.writeln('${styp} ${tmp_opt};')
+			g.writeln('if (${g.infix_left_var_name}) {')
+			g.indent++
+			g.write('${tmp_opt} = ')
+		} else {
 			g.write('${styp} ${tmp_opt} = ')
 		}
+	}
 	if node.is_method && !node.is_field {
 		if node.name == 'writeln' && g.pref.experimental && node.args.len > 0
 			&& node.args[0].expr is ast.StringInterLiteral
@@ -705,6 +712,11 @@ fn (mut g Gen) call_expr(node ast.CallExpr) {
 		g.or_block(tmp_opt, node.or_block, node.return_type)
 		unwrapped_typ := node.return_type.clear_flag(.optional).clear_flag(.result)
 		unwrapped_styp := g.typ(unwrapped_typ)
+		if g.infix_left_var_name.len > 0 {
+			g.indent--
+			g.writeln('}')
+			g.set_current_pos_as_last_stmt_pos()
+		}
 		if unwrapped_typ == ast.void_type {
 			g.write('\n ${cur_line}')
 		} else {

vlib/v/gen/c/infix.v

@@ -868,6 +868,24 @@ fn (mut g Gen) infix_expr_and_or_op(node ast.InfixExpr) {
 		g.expr(node.right)
 		g.infix_left_var_name = ''
 		return
+	} else if node.right is ast.CallExpr {
+		if node.right.or_block.kind != .absent {
+			prev_inside_ternary := g.inside_ternary
+			g.inside_ternary = 0
+			tmp := g.new_tmp_var()
+			cur_line := g.go_before_stmt(0).trim_space()
+			g.empty_line = true
+			g.write('bool ${tmp} = (')
+			g.expr(node.left)
+			g.writeln(');')
+			g.set_current_pos_as_last_stmt_pos()
+			g.write('${cur_line} ${tmp} ${node.op.str()} ')
+			g.infix_left_var_name = if node.op == .and { tmp } else { '!${tmp}' }
+			g.expr(node.right)
+			g.infix_left_var_name = ''
+			g.inside_ternary = prev_inside_ternary
+			return
+		}
 	}
 	g.gen_plain_infix_expr(node)
 }

vlib/v/tests/inout/printing_result_in_infix_expr.out

@@ -0,0 +1,3 @@
+test
+f2
+-> 03

vlib/v/tests/inout/printing_result_in_infix_expr.vv

@@ -0,0 +1,24 @@
+module main
+
+fn f2() bool {
+	println('f2')
+	return false
+}
+
+fn f3() !bool {
+	println('f3')
+	return false
+}
+
+fn test() ! {
+	println('test')
+	if f2() && f3()! {
+		println('-> 02')
+	} else {
+		println('-> 03')
+	}
+}
+
+fn main() {
+	test() or { panic(err) }
+}