This fixes usages of `Find`, `RFind` and the equality operator that kind of work right now but will break with the proper type checking of a templatized version of the string classes. For `Find` and `RFind` it appears that `nsCString::(R)Find("foo", 0)` calls were being coerced to the `Find(char*, bool, int, int)` versions. The intent was probably to just start searching from position zero. For the equality operator, the type of nullptr is nullptr_t rather than char(16_t)* so we'd need to add an operator overload that takes nullptr_t. In this case just using `IsVoid` is probably more appropriate.

(In reply to Eric Rahm [:erahm] (please no mozreview requests) from comment #0) > For the equality operator, the type of nullptr is nullptr_t rather than > char(16_t)* so we'd need to add an operator overload that takes nullptr_t. In > this case just using `IsVoid` is probably more appropriate. I'm surprised those are equivalent.

(In reply to David Baron :dbaron: ⌚️UTC-7 from comment #2) > (In reply to Eric Rahm [:erahm] (please no mozreview requests) from comment > #0) > > For the equality operator, the type of nullptr is nullptr_t rather than > > char(16_t)* so we'd need to add an operator overload that takes nullptr_t. In > > this case just using `IsVoid` is probably more appropriate. > > I'm surprised those are equivalent. Well I think the intent of |nsCString != nullptr| is the same as |!IsVoid()|, but you're right in practice [1] it's more of `!IsEmpty()`. Not sure if we should change it to do the "right" thing, or keep existing behavior. [1] http://searchfox.org/mozilla-central/rev/48ea452803907f2575d81021e8678634e8067fc2/xpcom/string/nsTSubstring.cpp#794-807

Comment on attachment 8900477 [details] [diff] [review] Fix improper usages of string functions Review of attachment 8900477 [details] [diff] [review]: ----------------------------------------------------------------- Those Find() functions are awful. ::: dom/media/gmp/ChromiumCDMChild.cpp @@ +231,5 @@ > // As laid out in the Chromium CDM API, if the CDM fails to load > // a session it calls OnResolveNewSessionPromise with nullptr as the sessionId. > // We can safely assume this means that we have failed to load a session > // as the other methods specify calling 'OnRejectPromise' when they fail. > + bool loadSuccessful = !aSessionId.IsVoid(); The incoming strings can be `nsCString(nullptr, 0)`, which I think becomes a non-void empty string, so this should probably be `!aSessionId.IsEmpty()` or equivalent.

https://hg.mozilla.org/integration/mozilla-inbound/rev/c5556637f69d48d84e51bfdb4c205a41ef2700e2 Bug 1393235 - Fix improper usages of string functions. r=njn