[PATCH] D51314: Parse compile commands lazily in InterpolatingCompilationDatabase

Ilya Biryukov via Phabricator via cfe-commits cfe-commits at lists.llvm.org
Tue Aug 28 01:14:48 PDT 2018

ilya-biryukov added inline comments.

Comment at: lib/Tooling/InterpolatingCompilationDatabase.cpp:124
+// A CompileCommand that can be applied to another file. Any instance of this
+// object is invalid after std::move() from it.
 struct TransferableCommand {
jfb wrote:
> This comment about `move` isn't really saying anything. Also, it's valid but unspecified (in the case of STL things). I'd drop it.
We specifically assert that object cannot be called after `move()` (check the unique_ptr that stores our `once_flag`). It's definitely undefined behavior to call any methods, because they will immediately dereference a null pointer (the aforementioned unique_ptr).

Happy to drop the comment, though, we do have asserts for that.

Comment at: lib/Tooling/InterpolatingCompilationDatabase.cpp:128
+      : OriginalCmd(std::move(C)),
+        TraitsComputed(llvm::make_unique<std::once_flag>()) {}
jfb wrote:
> The `once_flag` should just be a static, don't allocate it.
Sorry, I don't seem to follow. We need one `once_flag` per `TransferableCommand`

  rC Clang


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