[PATCH] D146971: [Sema] Populate declarations inside TypeLocs for some invalid types

[Ilya Biryukov via Phabricator via cfe-commits]

ilya-biryukov created this revision.
ilya-biryukov added reviewers: aaron.ballman, erichkeane.
Herald added a subscriber: arphaman.
Herald added a project: All.
ilya-biryukov requested review of this revision.
Herald added a project: clang.
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This also reverts 282cae0b9a602267ad7ef622f770066491332a11 <https://reviews.llvm.org/rG282cae0b9a602267ad7ef622f770066491332a11> as the
particular crash is now handled by the new code.

Before this change Clang would always leave declarations inside the
type-locs as `null` if the declarator had an invalid type. This patch
populates declarations even for invalid types if the structure of the
type and the type-locs match.

There are certain cases that may still cause crashes. These happen when
Clang recovers the type in a way that is not reflected in the
declarator's structure, e.g. adding a pointer when it was not present in
the code for ObjC interfaces or ignoring pointers written in the code
in C++ with auto return type (`auto* foo() -> int`). Those cases look
fixable with a better recovery strategy and I plan to follow up with
more patches to address those.

The first attempt caused 31 tests from `check-clang` to crash due to
different structure of the types and type-locs after certain errors. The
good news is that the failure is localized and mismatch in structures is
discovered by assertions inside `DeclaratorLocFiller`. Some notable
cases caught by existing tests:

- Invalid chunks when type is fully ignored and replace with int or now. Crashed in `C/C2x/n2838.c`.
- Invalid return types in lambdas. Crashed in `CXX/drs/dr6xx.cpp`.
- Invalid member pointers. Crashed in `CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p3-generic-lambda-1y.cpp`
- ObjC recovery that adds pointers. Crashed in `SemaObjC/blocks.m`

This change also updates the output of `Index/complete-blocks.m`.
Not entirely sure what causes the change, but the new function signature
is closer to the source code, so this seems like an improvement.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D146971

Files:
  clang/lib/Sema/SemaChecking.cpp
  clang/lib/Sema/SemaDeclCXX.cpp
  clang/lib/Sema/SemaLambda.cpp
  clang/lib/Sema/SemaTemplateInstantiate.cpp
  clang/lib/Sema/SemaType.cpp
  clang/test/Index/complete-blocks.m

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