JS: Consider empty regexp to be obviously empty

asgerf · asgerf · commit b4e6fb781ac1 · 2022-09-13T10:13:03.000+02:00
diff --git a/javascript/ql/src/RegExp/RegExpAlwaysMatches.ql b/javascript/ql/src/RegExp/RegExpAlwaysMatches.ql
@@ -54,6 +54,8 @@ predicate isUniversalRegExp(RegExpTerm term) {
     or
     child.(RegExpCharacterClass).isUniversalClass()
   )
+  or
+  term.(RegExpSequence).getNumChild() = 0
 }
 
 /**
diff --git a/javascript/ql/test/query-tests/RegExp/RegExpAlwaysMatches/tst.js b/javascript/ql/test/query-tests/RegExp/RegExpAlwaysMatches/tst.js
@@ -83,10 +83,10 @@ function nonWordBoundary(x) {
 }
 
 function emptyRegex(x) {
-  return new RegExp("").test(x); // NOT OK
+  return new RegExp("").test(x); // OK
 }
 
 function parserTest(x) {
   /(\w\s*:\s*[^:}]+|#){|@import[^\n]+(?:url|,)/.test(x); // OK
-  /^((?:a{0,2}|-)|\w\{\d,\d\})+X$/.text(x); // ok 
-}
+  /^((?:a{0,2}|-)|\w\{\d,\d\})+X$/.text(x); // ok
+}

Original file line number	Diff line number	Diff line change
`@@ -54,6 +54,8 @@ predicate isUniversalRegExp(RegExpTerm term) {`
`54`	`54`	`or`
`55`	`55`	`child.(RegExpCharacterClass).isUniversalClass()`
`56`	`56`	`)`
	`57`	`+ or`
	`58`	`+ term.(RegExpSequence).getNumChild() = 0`
`57`	`59`	`}`
`58`	`60`
`59`	`61`	`/**`
Original file line number	Diff line number	Diff line change
`@@ -83,10 +83,10 @@ function nonWordBoundary(x) {`
`83`	`83`	`}`
`84`	`84`
`85`	`85`	`function emptyRegex(x) {`
`86`		`- return new RegExp("").test(x); // NOT OK`
	`86`	`+ return new RegExp("").test(x); // OK`
`87`	`87`	`}`
`88`	`88`
`89`	`89`	`function parserTest(x) {`
`90`	`90`	`/(\w\s:\s[^:}]+\|#){\|@import[^\n]+(?:url\|,)/.test(x); // OK`
`91`		`- /^((?:a{0,2}\|-)\|\w\{\d,\d\})+X$/.text(x); // ok`
`92`		`-}`
	`91`	`+ /^((?:a{0,2}\|-)\|\w\{\d,\d\})+X$/.text(x); // ok`
	`92`	`+}`