|| true after macro invocation in StmtExpr parses oddly

[tomjakubowski]

For example:

#![feature(macro_rules)]

macro_rules! foo { () => { true } }

fn baz() -> bool {
    foo!() || true
}

fn main() { }

When compiled, produces these errors:

foo.rs:3:28: 3:32 error: mismatched types: expected `()`, found `bool` (expected (), found bool)
foo.rs:3 macro_rules! foo { () => { true } }
                                    ^~~~
foo.rs:3:1: 3:36 note: in expansion of foo!
foo.rs:6:5: 6:14 note: expansion site
foo.rs:6:12: 6:19 error: mismatched types: expected `bool`, found `|| -> bool` (expected bool, found fn)
foo.rs:6     foo!() || true
                    ^~~~~~~
error: aborting due to 2 previous errors

Whereas something like this does parse as intended:

#![feature(macro_rules)]

macro_rules! foo { () => { true } }

fn main() {
    if foo!() || true {

    }
}

The error is remedied by surrounding the whole expression in parentheses, turning it into a return statement, or doing something like let x = foo!() || true; x.

[tomjakubowski]

closing because this ought to be fixed by #18958