[PATCH] D105553: [analyzer][NFC] Split the main logic of NoStoreFuncVisitor to an abstract NoStateChangeVisitor class

Thu Jul 15 02:40:37 PDT 2021

Szelethus added a comment.

In D105553#2867881 <https://reviews.llvm.org/D105553#2867881>, @NoQ wrote:

> In the mailing list I seem to have made a mistake about how this works: we don't explicitly scan the AST for potential statements that could cause a state change (eg., assignment operators in case of `NoStore`) but we only check if the region was explicitly made accessible. This makes things a lot easier (we don't have to build an auxiliary AST-based analysis) and I'm not sure if this other heuristic that I thought we have would actually make things significantly better. I guess it makes sense to keep in mind that we might want to ultimately plug it in but I don't immediately see what'd stop us.

For `NoStoreFuncVisitor`, this seems to be fine I suppose, though I'm not sure how things pan out for memory leaks. As you put it,

> We probably shouldn't emit a note every time the function simply accepts the value of interest by pointer, because this doesn't necessarily prove the intent to delete the pointer;

it might be rather difficult to tell this intent. For now, I'm leaning on the side of slightly too much than too little, but I need real world data on my hand to have a good feel for it.

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Comment at: clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp:399
+/// to get the correct parameter name.
+static ArrayRef<ParmVarDecl *> getCallParameters(const CallEvent &Call) {
+  // Use runtime definition, if available.
----------------
NoQ wrote:
> While we're at it, can you take a look if the recently introduced `CallEvent::parameters()` is good enough for this?
I suppose yeah, at least the lit tests all passed, though its worth mentioning that this function explicitly calls `CallEvent::parameters()`...

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