regex: fix another inner literal bug

It looks like `is_simple` wasn't quite correct.

I can't wait until this code is rewritten. It is still not quite clearly
correct to me.

Fixes #1537

CHANGELOG.md

@@ -1,3 +1,11 @@
+TBD
+===
+Bug fixes:
+
+* [BUG #1537](https://github.com/BurntSushi/ripgrep/issues/1537):
+  Fix match bug caused by inner literal optimization.
+
+
 12.0.1 (2020-03-29)
 ===================
 ripgrep 12.0.1 is a small patch release that includes a minor bug fix relating

crates/regex/src/literal.rs

@@ -326,12 +326,12 @@ fn is_simple(expr: &Hir) -> bool {
         HirKind::Empty
         | HirKind::Literal(_)
         | HirKind::Class(_)
-        | HirKind::Repetition(_)
         | HirKind::Concat(_)
         | HirKind::Alternation(_) => true,
-        HirKind::Anchor(_) | HirKind::WordBoundary(_) | HirKind::Group(_) => {
-            false
-        }
+        HirKind::Anchor(_)
+        | HirKind::WordBoundary(_)
+        | HirKind::Group(_)
+        | HirKind::Repetition(_) => false,
     }
 }
 
@@ -412,8 +412,17 @@ mod tests {
         // https://github.com/BurntSushi/ripgrep/issues/1319
         assert_eq!(
             one_regex(r"TTGAGTCCAGGAG[ATCG]{2}C"),
-            pat("TTGAGTCCAGGAGA|TTGAGTCCAGGAGC|\
-                 TTGAGTCCAGGAGG|TTGAGTCCAGGAGT")
+            pat("TTGAGTCCAGGAG"),
         );
     }
+
+    #[test]
+    fn regression_1537() {
+        // Regression from:
+        // https://github.com/BurntSushi/ripgrep/issues/1537
+        assert_eq!(one_regex(r";(.*,)"), pat(";"));
+        assert_eq!(one_regex(r";((.*,))"), pat(";"));
+        assert_eq!(one_regex(r";(.*,)+"), pat(";"),);
+        assert_eq!(one_regex(r";(.*,){1}"), pat(";"),);
+    }
 }

tests/regression.rs

@@ -791,3 +791,11 @@ rgtest!(
         eqnice!("repotree/not-ignored\n", cmd.stdout());
     }
 );
+
+// See: https://github.com/BurntSushi/ripgrep/issues/1537
+rgtest!(r1537, |dir: Dir, mut cmd: TestCommand| {
+    dir.create("foo", "abc;de,fg");
+
+    let expected = "foo:abc;de,fg\n";
+    eqnice!(expected, cmd.arg(";(.*,){1}").stdout());
+});