[PATCH] D142606: Lazyly initialize uncommon toolchain detector

[Markus Böck via Phabricator via cfe-commits]

zero9178 added inline comments.


================
Comment at: clang/lib/Driver/ToolChains/LazyDetector.h:26
+
+  mutable std::optional<T> Detector;
+
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serge-sans-paille wrote:
> zero9178 wrote:
> > Any reason this is `mutable`? I don't see it being used a non-const way in a const method
> yeah, `T const *operator->() const` updates the optional by actually creating the value. (`std::optional::empalce` is not const)
Your `T const *operator->() const` method does not do so, `T *operator->()` does, which is non-const and hence can call `emplace` without issues. 
So as far as C++ goes it is not required. 


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  https://reviews.llvm.org/D142606/new/

https://reviews.llvm.org/D142606