[llvm] [Support] Accept -no-<name> to negate cl::opt<bool> (PR #224978)

[Fangrui Song via llvm-commits]

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@@ -292,6 +292,9 @@ class LLVM_ABI Option {
     return Value ? ((enum ValueExpected)Value) : getValueExpectedFlagDefault();
   }
 
+  // Whether -no-<ArgStr> is accepted and sets the option to false.
+  virtual bool isNegatable() const { return false; }
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MaskRay wrote:

Switched to a MiscFlags bit.

https://github.com/llvm/llvm-project/pull/224978