JavaScript: Produce friendlier message for empty-string replacements.

Max Schaefer · Max Schaefer · commit 659c67c715a6 · 2018-09-25T11:27:12.000+01:00
diff --git a/javascript/ql/src/RegExp/IdentityReplacement.ql b/javascript/ql/src/RegExp/IdentityReplacement.ql
@@ -60,8 +60,9 @@ predicate regExpMatchesString(RegExpTerm t, string s) {
   )
 }
 
-from MethodCallExpr repl, string s
+from MethodCallExpr repl, string s, string friendly
 where repl.getMethodName() = "replace" and
       matchesString(repl.getArgument(0), s) and
-      repl.getArgument(1).getStringValue() = s
-select repl.getArgument(0), "This replaces '" + s + "' with itself."
+      repl.getArgument(1).getStringValue() = s and
+      (if s = "" then friendly = "the empty string" else friendly = "'" + s + "'")
+select repl.getArgument(0), "This replaces " + friendly + " with itself."

Original file line number	Diff line number	Diff line change
`@@ -60,8 +60,9 @@ predicate regExpMatchesString(RegExpTerm t, string s) {`
`60`	`60`	`)`
`61`	`61`	`}`
`62`	`62`
`63`		`-from MethodCallExpr repl, string s`
	`63`	`+from MethodCallExpr repl, string s, string friendly`
`64`	`64`	`where repl.getMethodName() = "replace" and`
`65`	`65`	`matchesString(repl.getArgument(0), s) and`
`66`		`- repl.getArgument(1).getStringValue() = s`
`67`		`-select repl.getArgument(0), "This replaces '" + s + "' with itself."`
	`66`	`+ repl.getArgument(1).getStringValue() = s and`
	`67`	`+ (if s = "" then friendly = "the empty string" else friendly = "'" + s + "'")`
	`68`	`+select repl.getArgument(0), "This replaces " + friendly + " with itself."`