[PATCH] [clang-tidy] Add support for boolean check options.

[Manuel Klimek]

================
Comment at: clang-tidy/ClangTidy.h:68-80
@@ -67,1 +67,15 @@
 
+  /// \brief Read a named option from the \c Context and parse it as bool.
+  ///
+  /// Reads the option with the check-local name \p LocalName from the
+  /// \c CheckOptions. If the corresponding key is not present, returns
+  /// \p Default.
+  bool get(StringRef LocalName, bool Default) const {
+    std::string Value = get(LocalName, "");
+    if (Value == "true")
+      return true;
+    if (Value == "false")
+      return false;
+    return Default;
+  }
+
----------------
alexfh wrote:
> klimek wrote:
> > alexfh wrote:
> > > klimek wrote:
> > > > alexfh wrote:
> > > > > klimek wrote:
> > > > > > alexfh wrote:
> > > > > > > klimek wrote:
> > > > > > > > alexfh wrote:
> > > > > > > > > klimek wrote:
> > > > > > > > > > Why do we want unknown values to give Default? If we do, we should put it into the comments; can we rather make them given an error while parsing, and then do:
> > > > > > > > > > return get(LocalName, Default ? "true" : "false") == "true";
> > > > > > > > > We can't error out early enough as check options are parsed after the configuration is read. So I don't currently see a better way than to fall back to default.
> > > > > > > > Fall back to false?
> > > > > > > Could you explain why this would be better?
> > > > > > If we catch the error in the config later on, and give a nice error, it doesn't matter, and the code gets simpler.
> > > > > > 
> > > > > > If we cannot catch the error, I would like an explicitly given config to not lead to different behavior depending on the default value; I find that unexpected. Plus, I think it would make the code simpler.
> > > > > > If we catch the error in the config later on, and give a nice error,
> > > > > 
> > > > > Not sure yet if this can be done nicely.
> > > > > 
> > > > > > it doesn't matter, and the code gets simpler.
> > > > > 
> > > > > It doesn't make the code simpler, as we still need to handle missing value and return Default. 
> > > > > 
> > > > > > If we cannot catch the error, I would like an explicitly given config to not lead to different behavior depending on the default value; I find that unexpected. 
> > > > > 
> > > > > Why? On the opposite, I think that the case of invalid value is close to the case of missing value, so using the same default is more intuitive.
> > > > > 
> > > > > > Plus, I think it would make the code simpler.
> > > > > 
> > > > > Not really. The code is now common for all types having ScalarTraits<>. It also falls back to Default in case of error, and there I don't see another reasonable value to fall back to in case the parsing fails.
> > > > Ok, I'm convinced:
> > > > If this is really the same handling for all scalar values, I find it significantly worse if we silently eat up parsing errors. I'd prefer crashing with an error message if that's the only way possible.
> > > Crashing doesn't seem like a the best solution. We could (mis)use diagnostic output to report configuration errors. WDYT?
> > > 
> > > For now, I've changed OptionsView::get<> to propagate errors to the caller. And the caller can decide whether to crash in case of an error or handle it in a different way. I've changed two current users of this method to use ErrorOr<>::operator* which asserts that there's no value. Do we want to add some kind of a getValueOrCrash method to ErrorOr<> which would use report_fatal_error instead?
> > +1 to some form of diagnostic. Also +1 for handing to to the caller.
> > Is there a way where the caller can just ask whether there's a value?
> We can add OptionsView::get overloads that return Optional<Something> (though not sure why would callers bother using it instead of the versions with default).
I meant as opposed to an error. Otherwise I don't understand your last comment above:
""" I've changed two current users of this method to use ErrorOr<>::operator* which asserts that there's no value. Do we want to add some kind of a getValueOrCrash method to ErrorOr<> which would use report_fatal_error instead?"""

http://reviews.llvm.org/D5602