[all-commits] [llvm/llvm-project] faef8b: [webkit.RefCntblBaseVirtualDtor] Allow CRTP classe...

[Ryosuke Niwa via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: faef8b4aa245a671e2013319e8073a9fc52ae12e
      https://github.com/llvm/llvm-project/commit/faef8b4aa245a671e2013319e8073a9fc52ae12e
  Author: Ryosuke Niwa <rniwa at webkit.org>
  Date:   2024-05-25 (Sat, 25 May 2024)

  Changed paths:
    M clang/lib/StaticAnalyzer/Checkers/WebKit/RefCntblBaseVirtualDtorChecker.cpp
    M clang/test/Analysis/Checkers/WebKit/ref-cntbl-base-virtual-dtor-ref-deref-on-diff-classes.cpp
    M clang/test/Analysis/Checkers/WebKit/ref-cntbl-base-virtual-dtor-templates.cpp

  Log Message:
  -----------
  [webkit.RefCntblBaseVirtualDtor] Allow CRTP classes without a virtual destructor. (#92837)

Exempt CRTP (Curiously Recurring Template Pattern) classes with a delete
operation acting on "this" pointer with an appropriate cast from the
requirement that a ref-countable superclass must have a virtual
destructor.

To do this, this PR introduces new DerefFuncDeleteExprVisitor, which
looks for a delete operation with an explicit cast to the derived class
in a base class.

This PR also changes the checker so that we only check a given class's
immediate base class instead of all ancestor base classes in the class
hierarchy. This is sufficient because the checker will eventually see
the definition for every class in the class hierarchy and transitively
proves every ref-counted base class has a virtual destructor or deref
function which casts this pointer back to the derived class before
deleting. Without this change, we would keep traversing the same list of
base classes whenever we encounter a new subclass, which is wholly
unnecessary.

It's possible for DerefFuncDeleteExprVisitor to come to a conclusoin that
there isn't enough information to determine whether a given templated
superclass invokes delete operation on a subclass when the template
isn't fully specialized for the subclass. In this case, we return
std::nullopt in HasSpecializedDelete, and visitCXXRecordDecl will skip
this declaration. This is okay because the checker will eventually see a
concreate fully specialized class definition if it ever gets
instantiated.



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