Branch can never match because an earlier branch covers it
medium
A later, more specific rule (www.corp.example -> proxy) is unreachable because an earlier, broader rule (*.corp.example -> DIRECT) returns for the same hosts. First match wins.
Why it matters
PAC functions are sequences of if (...) return; the first matching branch decides. When a
broad pattern precedes a narrower one for the same hosts, the narrower rule is dead code.
The typical story: an exception for one host was appended at the end of the file, below the
wildcard that already catches it, and “does not work”. Detection compares literal patterns
for subsumption (glob implies glob, suffix implies suffix, exact name under suffix).
Draft: the subsumption logic needs care with mixed function types and is still pending in the detector design.
How to fix
Order rules from specific to general, or remove the unreachable rule.
Examples
Bad
function FindProxyForURL(url, host) {
if (shExpMatch(host, "*.corp.example")) {
return "DIRECT";
}
if (host == "www.corp.example") {
return "PROXY proxy.corp.example:8080";
}
return "PROXY proxy.corp.example:8080";
}
Good
function FindProxyForURL(url, host) {
if (host == "www.corp.example") {
return "PROXY proxy.corp.example:8080";
}
if (shExpMatch(host, "*.corp.example")) {
return "DIRECT";
}
return "PROXY proxy.corp.example:8080";
}