[PATCH] D64448: gsl::Owner/gsl::Pointer: Add implicit annotations for some std types

[Matthias Gehre via Phabricator via cfe-commits]

mgehre created this revision.
mgehre added reviewers: gribozavr, xazax.hun.
Herald added a subscriber: rnkovacs.
Herald added a project: clang.

Make the DerefType, i.e. the argument of gsl::Owner/gsl::Pointer optional for now.

The DerefType is used when infering lifetime annotations of functions, e.g.
how a return value can relate to the arguments. Our initial checks should
work without that kind of inference and instead use explicit annotations,
so we don't need the DerefType right now.
And having it optional makes the implicit/default annotations for std:: types
easier to implement. I think the DerefType is also optional in the current MSVC
implementation.

This seems to be the first attribute that has an optional Type argument,
so I needed to fix two thinks in tablegen:

- Don't crash AST dump when Owner/Pointer has no Type argument
- Don't crash when pretty-printing an Attribute with optional type argument

Add __is_gsl_owner/__is_gsl_pointer builtins. They are very useful to test
if the annotations have been attached correctly.

Hard code gsl::Owner/gsl::Pointer for std types. The paper mentions
some types explicitly. Generally, all containers and their iterators are
covered. For iterators, we cover both the case that they are defined
as an nested class or as an typedef/using. I have started to test this
implementation against some real standard library implementations, namely
libc++ 7.1.0, libc++ 8.0.1rc2, libstdc++ 4.6.4, libstdc++ 4.8.5,
libstdc++ 4.9.4, libstdc++ 5.4.0, libstdc++ 6.5.0, libstdc++ 7.3.0,
libstdc++ 8.3.0 and libstdc++ 9.1.0.

The tests are currently here

  https://github.com/mgehre/llvm-project/blob/lifetime-ci/lifetime-attr-test.sh
  https://github.com/mgehre/llvm-project/blob/lifetime-ci/lifetime-attr-test.cpp

I think due to their dependency on a standard library, they are not a good fit
for clang/test/. Where else could I put them?


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D64448

Files:
  clang/docs/LanguageExtensions.rst
  clang/include/clang/Basic/Attr.td
  clang/include/clang/Basic/AttrDocs.td
  clang/include/clang/Basic/TokenKinds.def
  clang/include/clang/Basic/TypeTraits.h
  clang/include/clang/Sema/Sema.h
  clang/lib/Sema/SemaAttr.cpp
  clang/lib/Sema/SemaDecl.cpp
  clang/lib/Sema/SemaDeclAttr.cpp
  clang/lib/Sema/SemaExprCXX.cpp
  clang/lib/Sema/SemaTemplate.cpp
  clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
  clang/test/AST/ast-dump-attr.cpp
  clang/test/SemaCXX/attr-gsl-owner-pointer.cpp
  clang/utils/TableGen/ClangAttrEmitter.cpp

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