softdevteam / fm Goto Github PK

Here's an in interesting one.

assert!(helper("$1 $1 $1", "a a a"));
assert!(helper("$1 $2 $3", "a a a"));

Using the same name matchers as in the repo.

I expected the latter to fail because I wasn't expecting different names to be allowed to assume the same value.

Now a real world example. Here's what a TIR test looks like:

assert_tir(
    "live($a)\n\
    $a = call(add6, [1u64, 1u64, 1u64, 1u64, 1u64, 1u64])\n\
    dead($a)",
    &tir_trace,
);

assert_tir() just stringifies the TIR trace and tries to match the given pattern using the following name matchers:

let ptn_re = Regex::new(r"\$.+?\b").unwrap();
let text_re = Regex::new(r"\$?.+?\b").unwrap(); // Optional `$` prefix.

Then to test a failing match, I naively flipped $a on the first line of the pattern to $c and was surprised to see it matched. Of course, it's ok for both $a and $c to match the same content.

But should it be? Perhaps I want to know that the variable used in live is distinct from the one in the call and the dead.

I added the test:

assert_eq!(helper("...\nline2\nline3\nline4\n", "line1\nline2\nline3\nbadgers\nline5"), 4);

Which gives fails, as the failure line reported is 3, not as I expected 4. I expected 4 because the first line in the text which doesn't match is badgers on line 4.

Did I misunderstand something, or is that a bug?

@vext01 and I triggered a bug in FM. If your pattern has two consecutive wildcards with a newline in between FM crashes:

thread 'tests::defaults' panicked at 'begin <= end (3 <= 0) when slicing `...`', src/lib.rs:357:28

See test:

diff --git a/src/lib.rs b/src/lib.rs
index c4fbca4..1c83515 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -523,6 +523,7 @@ mod tests {
             FMatcher::new(ptn).unwrap().matches(text).is_ok()
         }
         assert!(helper("", ""));
+        assert!(helper("...\n...", ""));
         assert!(helper("\n", ""));
         assert!(helper("", "\n"));
         assert!(helper("a", "a"));

I guess it doesn't make sense to do this in a pattern, but maybe a user friendly message would help here.

I've added the following case to the name matcher test:

 assert!(helper("$1", "$2")); 

The regexs in the helper remain the same:

let nameptn_re = Regex::new(r"\$.+?\b").unwrap();
let name_re = Regex::new(r".+?\b").unwrap();

The FM matcher fails to match this.

I was expecting this to match, because the following assertions are true:

    assert!(Regex::new(r"\$.+?\b").unwrap().is_match("$1"));
    assert!(Regex::new(r".+?\b").unwrap().is_match("$2"));

Playground

I'm not sure if my expectations are wrong, or if it's a bug.