[llvm-dev] Spurious cast warning for C++? (original) (raw)
Richard Smith via llvm-dev llvm-dev at lists.llvm.org
Tue Apr 11 15:10:12 PDT 2017
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On 10 April 2017 at 07:33, David Blaikie via llvm-dev < llvm-dev at lists.llvm.org> wrote:
For the case of a redundant or unneeded std::move, I think Clang already has something like that...
Ah, it doesn't quite catch that particular case. Richard - would it be reasonable to extend the pessimizing move warning (well, I guess not - maybe as a separate warning) for cases like this: void f(const foo&); void g(foo x) { f(std::move(x)); } Or maybe there's already a clang-tidy check for this sort of redundant move?
There's already a clang warning for redundant moves (-Wredundant-move). It doesn't yet catch the above pattern, but it should...
On Sun, Apr 9, 2017 at 12:01 PM Brennan Vincent via llvm-dev <_ _llvm-dev at lists.llvm.org> wrote:
How difficult would it be to add a warning to Clang when the programmer performs a cast that provably has no effect?
A particular case I have in mind is someone getting confused and calling std::move on an argument to a copy-constructor for a class that doesn't implement move semantics. I would be grateful if someone either (1) told me why this is difficult/impossible, or (2) gave me some pointers to where I could start trying to implement it...
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