[all-commits] [llvm/llvm-project] 770cd2: [lldb][ClangExpressionParser] Don't leak memory wh...

[Michael Buch via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 770cd24140038646539602406fff54497793dae8
      https://github.com/llvm/llvm-project/commit/770cd24140038646539602406fff54497793dae8
  Author: Michael Buch <michaelbuch12 at gmail.com>
  Date:   2024-08-20 (Tue, 20 Aug 2024)

  Changed paths:
    M lldb/source/Plugins/ExpressionParser/Clang/ASTUtils.cpp
    M lldb/source/Plugins/ExpressionParser/Clang/ASTUtils.h
    M lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp

  Log Message:
  -----------
  [lldb][ClangExpressionParser] Don't leak memory when multiplexing ExternalASTSources (#104799)

When we use `SemaSourceWithPriorities` as the `ASTContext`s
ExternalASTSource, we allocate a `ClangASTSourceProxy` (via
`CreateProxy`) and two `ExternalASTSourceWrapper`. Then we push these
sources into a vector in `SemaSourceWithPriorities`. The allocated
`SemaSourceWithPriorities` itself will get properly deallocated because
the `ASTContext` wraps it in an `IntrusiveRefCntPtr`. But the three
sources we allocated earlier will never get released.

This patch fixes this by mimicking what `MultiplexExternalSemaSource`
does (which is what `SemaSourceWithPriorities` is based on anyway).
I.e., when `SemaSourceWithPriorities` gets constructed, it increments
the use count of its sources. And on destruction it decrements them.

Similarly, to make sure we dealloacted the `ClangASTProxy` properly, the
`ExternalASTSourceWrapper` now assumes shared ownership of the
underlying source.



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