[PATCH] D43056: [CFG] [analyzer] Add construction context for CXXBindTemporaryExpr.

[Artem Dergachev via Phabricator via cfe-commits]

NoQ created this revision.
NoQ added reviewers: dcoughlin, xazax.hun, a.sidorin, george.karpenkov, szepet.
Herald added subscribers: cfe-commits, rnkovacs.

This covers temporary constructors for which a destructor is necessary. It is necessary to support `CXXTemporaryObjectExpr` here, which is a "constructor in the middle of nowhere" expression like `C()` - it's a sub-class of `CXXConstructExpr` which we didn't even notice yet because it didn't appear in construction contexts we added support for in the previous patches, but it does commonly appear in `CXXBindTemporaryExpr`s and failing to consume the construction context would trigger the construction context overwrite assertion.

Note that when the destructor is trivial, `CXXBindTemporaryExpr` is omitted, and in that case we don't provide any construction context yet. In such cases there's no trigger statement at all, for example the following code:

  struct S {};
  
  void foo() {
    S();
  }

would produce the following AST:

  `-FunctionDecl 0x7fea280366a0 <line:3:1, line:5:1> line:3:6 foo 'void ()'
    `-CompoundStmt 0x7fea28036d98 <col:12, line:5:1>
      `-CXXTemporaryObjectExpr 0x7fea28036c70 <line:4:3, col:5> 'S' 'void () noexcept' zeroing

... and that's it.

So in that case we'd have to make a special kind of construction context that merely conveys that we are sure that we are indeed constructing a simple temporary object because we were directly told to do so by the programmer. But that's another story.


Repository:
  rC Clang

https://reviews.llvm.org/D43056

Files:
  lib/Analysis/CFG.cpp
  test/Analysis/auto-obj-dtors-cfg-output.cpp
  test/Analysis/cfg-rich-constructors.cpp
  test/Analysis/temp-obj-dtors-cfg-output.cpp

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