[PATCH] D126061: [clang] [WIP] Reject non-declaration C++11 attributes on declarations

[Martin Böhme via Phabricator via cfe-commits]

mboehme created this revision.
Herald added a reviewer: aaron.ballman.
Herald added a subscriber: jdoerfert.
Herald added a project: All.
mboehme requested review of this revision.
Herald added a reviewer: jdoerfert.
Herald added subscribers: cfe-commits, sstefan1.
Herald added a project: clang.

(Iteration #4)

For backwards compatiblity, we emit only a warning instead of an error if the
attribute is one of the existing type attributes that we have historically
allowed to "slide" to the `DeclSpec` just as if it had been specified in GNU
syntax. (We will call these "legacy type attributes" below.)

The high-level changes that achieve this are:

- We introduce a new field `Declarator::DeclarationAttrs` (with appropriate accessors) to store C++11 attributes occurring in the attribute-specifier-seq at the beginning of a simple-declaration (and other similar declarations). Previously, these attributes were placed on the `DeclSpec`, which made it impossible to reconstruct later on whether the attributes had in fact been placed on the decl-specifier-seq or ahead of the declaration.

- In the parser, we propgate declaration attributes and decl-specifier-seq attributes separately until we can place them in `Declarator::DeclarationAttrs` or `DeclSpec::Attrs`, respectively.

- In `ProcessDeclAttributes()`, in addition to processing declarator attributes, we now also process the attributes from `Declarator::DeclarationAttrs` (except if they are legacy type attributes).

- In `ConvertDeclSpecToType()`, in addition to processing `DeclSpec` attributes, we also process any legacy type attributes that occur in `Declarator::DeclarationAttrs` (and emit a warning).

- We make `ProcessDeclAttribute` emit an error if it sees any non-declaration attributes in C++11 syntax, except in the following cases:
  - If it is being called for attributes on a `DeclSpec` or `DeclaratorChunk`
  - If the attribute is a legacy type attribute (in which case we only emit a warning)

The standard justifies treating attributes at the beginning of a
simple-declaration and attributes after a declarator-id the same. Here are some
relevant parts of the standard:

- The attribute-specifier-seq at the beginning of a simple-declaration "appertains to each of the entities declared by the declarators of the init-declarator-list" (https://eel.is/c++draft/dcl.dcl#dcl.pre-3)

- "In the declaration for an entity, attributes appertaining to that entity can appear at the start of the declaration and after the declarator-id for that declaration." (https://eel.is/c++draft/dcl.dcl#dcl.pre-note-2)

- "The optional attribute-specifier-seq following a declarator-id appertains to the entity that is declared." (https://eel.is/c++draft/dcl.dcl#dcl.meaning.general-1)

The standard contains similar wording to that for a simple-declaration in other
similar types of declarations, for example:

- "The optional attribute-specifier-seq in a parameter-declaration appertains to the parameter." (https://eel.is/c++draft/dcl.fct#3)

- "The optional attribute-specifier-seq in an exception-declaration appertains to the parameter of the catch clause" (https://eel.is/c++draft/except.pre#1)

The new behavior is tested both on the newly added type attribute
`annotate_type`, for which we emit errors, and for the legacy type attribute
`address_space` (chosen somewhat randomly from the various legacy type
attributes), for which we emit warnings.

Depends On D111548 <https://reviews.llvm.org/D111548>


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D126061

Files:
  clang/include/clang/Basic/AttributeCommonInfo.h
  clang/include/clang/Basic/DiagnosticSemaKinds.td
  clang/include/clang/Parse/Parser.h
  clang/include/clang/Parse/RAIIObjectsForParser.h
  clang/include/clang/Sema/DeclSpec.h
  clang/include/clang/Sema/ParsedAttr.h
  clang/include/clang/Sema/Sema.h
  clang/lib/Basic/Attributes.cpp
  clang/lib/Parse/ParseDecl.cpp
  clang/lib/Parse/ParseDeclCXX.cpp
  clang/lib/Parse/ParseExprCXX.cpp
  clang/lib/Parse/ParseObjc.cpp
  clang/lib/Parse/ParseStmt.cpp
  clang/lib/Parse/ParseTemplate.cpp
  clang/lib/Parse/Parser.cpp
  clang/lib/Sema/ParsedAttr.cpp
  clang/lib/Sema/SemaDecl.cpp
  clang/lib/Sema/SemaDeclAttr.cpp
  clang/lib/Sema/SemaType.cpp
  clang/test/Sema/annotate-type.c
  clang/test/SemaCXX/address-space-placement.cpp
  clang/test/SemaCXX/annotate-type.cpp
  clang/test/SemaOpenCL/address-spaces.cl
  clang/utils/TableGen/ClangAttrEmitter.cpp

-------------- next part --------------
A non-text attachment was scrubbed...
Name: D126061.430941.patch
Type: text/x-patch
Size: 74662 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20220520/9eb11482/attachment-0001.bin>