This is a major change on how we represent nested name qualifications in
the AST.
* The nested name specifier itself and how it's stored is changed. The
prefixes for types are handled within the type hierarchy, which makes
canonicalization for them super cheap, no memory allocation required.
Also translating a type into nested name specifier form becomes a no-op.
An identifier is stored as a DependentNameType. The nested name
specifier gains a lightweight handle class, to be used instead of
passing around pointers, which is similar to what is implemented for
TemplateName. There is still one free bit available, and this handle can
be used within a PointerUnion and PointerIntPair, which should keep
bit-packing aficionados happy.
* The ElaboratedType node is removed, all type nodes in which it could
previously apply to can now store the elaborated keyword and name
qualifier, tail allocating when present.
* TagTypes can now point to the exact declaration found when producing
these, as opposed to the previous situation of there only existing one
TagType per entity. This increases the amount of type sugar retained,
and can have several applications, for example in tracking module
ownership, and other tools which care about source file origins, such as
IWYU. These TagTypes are lazily allocated, in order to limit the
increase in AST size.
This patch offers a great performance benefit.
It greatly improves compilation time for
[stdexec](https://github.com/NVIDIA/stdexec). For one datapoint, for
`test_on2.cpp` in that project, which is the slowest compiling test,
this patch improves `-c` compilation time by about 7.2%, with the
`-fsyntax-only` improvement being at ~12%.
This has great results on compile-time-tracker as well:
This patch also further enables other optimziations in the future, and
will reduce the performance impact of template specialization resugaring
when that lands.
It has some other miscelaneous drive-by fixes.
About the review: Yes the patch is huge, sorry about that. Part of the
reason is that I started by the nested name specifier part, before the
ElaboratedType part, but that had a huge performance downside, as
ElaboratedType is a big performance hog. I didn't have the steam to go
back and change the patch after the fact.
There is also a lot of internal API changes, and it made sense to remove
ElaboratedType in one go, versus removing it from one type at a time, as
that would present much more churn to the users. Also, the nested name
specifier having a different API avoids missing changes related to how
prefixes work now, which could make existing code compile but not work.
How to review: The important changes are all in
`clang/include/clang/AST` and `clang/lib/AST`, with also important
changes in `clang/lib/Sema/TreeTransform.h`.
The rest and bulk of the changes are mostly consequences of the changes
in API.
PS: TagType::getDecl is renamed to `getOriginalDecl` in this patch, just
for easier to rebasing. I plan to rename it back after this lands.
Fixes#136624
Fixes https://github.com/llvm/llvm-project/issues/43179
Fixes https://github.com/llvm/llvm-project/issues/68670
Fixes https://github.com/llvm/llvm-project/issues/92757
Add `NamespaceBaseDecl` as common base class of `NamespaceDecl` and
`NamespaceAliasDecl`. This simplifies `NestedNameSpecifier` a bit.
Co-authored-by: Matheus Izvekov <mizvekov@gmail.com>
This paper removes UB around use of void expressions. Previously, code
like this had undefined behavior:
```
void foo(void) {
(void)(void)1;
extern void x;
x;
}
```
and this is now well-defined in C2y. Functionally, this now means that
it is valid to use `void` as a `_Generic` association.
This patch replaces uses of StringRef::{starts,ends}with with
StringRef::{starts,ends}_with for consistency with
std::{string,string_view}::{starts,ends}_with in C++20.
I'm planning to deprecate and eventually remove
StringRef::{starts,ends}with.
These are still disabled by default, but will work in ObjC code if you
enable the `-import-insertions` flag.
Completion requires ASTSignals to be available; before ASTSignals are
available, we will always use #include. Once they are available, the
behavior varies as follows:
- For source files, use #import if the ObjC language flag is enabled
- For header files:
- If the ObjC language flag is disabled, use #include
- If the header file contains any #imports, use #import
- If the header file references any ObjC decls, use #import
- Otherwise, use #include
IncludeFixer support is similar, but it does not rely upon ASTSignals,
instead it does the above checks excluding the scan for ObjC symbols.
Differential Revision: https://reviews.llvm.org/D139458
And make use of this from clangd's CodeComplete and IncludeFixer, although currently they are both restricted only to #include symbols.
Differential Revision: https://reviews.llvm.org/D128677
The IncludeDirective contains both Include (the current behavior) and Import,
which we can use in the future to provide #import suggestions for
Objective-C files/symbols.
Differential Revision: https://reviews.llvm.org/D128457
This patch mechanically replaces None with std::nullopt where the
compiler would warn if None were deprecated. The intent is to reduce
the amount of manual work required in migrating from Optional to
std::optional.
This is part of an effort to migrate from llvm::Optional to
std::optional:
https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716
llvm::sort is beneficial even when we use the iterator-based overload,
since it can optionally shuffle the elements (to detect
non-determinism). However llvm::sort is not usable everywhere, for
example, in compiler-rt.
Reviewed By: nhaehnle
Differential Revision: https://reviews.llvm.org/D130406
In C++ and C2x, we would avoid calling ImplicitlyDefineFunction at all,
but in OpenCL mode we would still call the function and have it produce
an error diagnostic. Instead, we now have a helper function to
determine when implicit function definitions are allowed and we use
that to determine whether to call ImplicitlyDefineFunction so that the
behavior is more consistent across language modes.
This changes the diagnostic behavior from telling the users that an
implicit function declaration is not allowed in OpenCL to reporting use
of an unknown identifier and going through typo correction, as done in
C++ and C2x.
C89 had a questionable feature where the compiler would implicitly
declare a function that the user called but was never previously
declared. The resulting function would be globally declared as
extern int func(); -- a function without a prototype which accepts zero
or more arguments.
C99 removed support for this questionable feature due to severe
security concerns. However, there was no deprecation period; C89 had
the feature, C99 didn't. So Clang (and GCC) both supported the
functionality as an extension in C99 and later modes.
C2x no longer supports that function signature as it now requires all
functions to have a prototype, and given the known security issues with
the feature, continuing to support it as an extension is not tenable.
This patch changes the diagnostic behavior for the
-Wimplicit-function-declaration warning group depending on the language
mode in effect. We continue to warn by default in C89 mode (due to the
feature being dangerous to use). However, because this feature will not
be supported in C2x mode, we've diagnosed it as being invalid for so
long, the security concerns with the feature, and the trivial
workaround for users (declare the function), we now default the
extension warning to an error in C99-C17 mode. This still gives users
an easy workaround if they are extensively using the extension in those
modes (they can disable the warning or use -Wno-error to downgrade the
error), but the new diagnostic makes it more clear that this feature is
not supported and should be avoided. In C2x mode, we no longer allow an
implicit function to be defined and treat the situation the same as any
other lookup failure.
Differential Revision: https://reviews.llvm.org/D122983
A function call `unresolved()` in C will generate an implicit declaration
of the missing function and warn `ext_implicit_function_decl` or so.
(Compared to in C++ where we get `err_undeclared_var_use`).
We want to try to resolve these names.
Unfortunately typo correction is disabled in sema for performance
reasons unless this warning is promoted to error.
(We need typo correction for include-fixer.)
It's not clear to me where a switch to force this correction on should
go, include-fixer is kind of a hack. So hack more by telling sema we're
promoting them to error.
Fixes https://github.com/clangd/clangd/issues/937
Differential Revision: https://reviews.llvm.org/D115490
Clang doesn't offer these fixes I guess for a couple of reasons:
- where to insert includes is a formatting concern, and clang shouldn't
depend on clang-format
- the way clang prints diagnostics, we'd show a bunch of basically irrelevant
context of "this is where we'd want to insert the include"
Maybe it's possible to hack around 1, but 2 is still a concern.
Meanwhile, bolting this onto include-fixer gets the job done.
Fixes https://github.com/clangd/clangd/issues/355
Fixes https://github.com/clangd/clangd/issues/937
Differential Revision: https://reviews.llvm.org/D114667
We were default initializing SymbolIDs before, which would leave
indeterminate values in underlying std::array.
This patch updates the underlying data initalization to be value-init and adds a
way to check for validness of a SymbolID.
Differential Revision: https://reviews.llvm.org/D90397
This is how it should've been and brings it more in line with
std::string_view. There should be no functional change here.
This is mostly mechanical from a custom clang-tidy check, with a lot of
manual fixups. It uncovers a lot of minor inefficiencies.
This doesn't actually modify StringRef yet, I'll do that in a follow-up.
Summary:
Computing lazily leads to crashes. In particular, computing scopes may
produce diagnostics (from inside template instantiations) and we
currently do it when processing another diagnostic, which leads to
crashes.
Moreover, we remember and access 'Scope*' when computing scopes. This
might lead to invalid memory access if the Scope is deleted by the time
we run the delayed computation. We did not actually construct an example
when this happens, though.
From the VCS and review history, it seems the optimization was
introduced in the initial version without a mention of any performance
benchmarks justifying the performance gains. This led me to a
conclusion that the optimization was premature, so removing it to avoid
crashes seems like the right trade-off at that point.
Reviewers: sammccall
Reviewed By: sammccall
Subscribers: MaskRay, jkorous, arphaman, kadircet, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D65796
llvm-svn: 368019
Summary:
Currently HeaderSearch only looks at SearchDir's passed into it, but in
addition to those paths headers can be relative to including file's directory.
This patch makes sure that is taken into account.
Reviewers: gribozavr
Subscribers: jkorous, arphaman, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D63295
llvm-svn: 365005
Summary:
Previously, we would use include spelling of the declaring header to check
whether the inserted header is the same as the main file. This doesn't help because
we only have file path of the main file.
Reviewers: sammccall
Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, kadircet, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D60687
llvm-svn: 358496
Summary:
In the following examples, "clangd" is unresolved, and the fixer will try to fix
include for `clang::clangd`; however, clang::clangd::X is usually intended. So
when handling a qualifier that is unresolved, we change the unresolved name and
scopes so that the fixer will fix "clang::clangd::X" in the following example.
```
namespace clang {
clangd::X
~~~~~~
}
// or
clang::clangd::X
~~~~~~
```
Reviewers: sammccall
Reviewed By: sammccall
Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, kadircet, jdoerfert, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D58185
llvm-svn: 354330
Summary:
Multiple diagnostics can be caused by the same unresolved name or incomplete type,
especially if the code is copy-pasted without #includes. The cache can avoid making
repetitive index requests, and thus reduce latency and allow more diagnostics to be
fixed (we limit the number of index requests for each parse).
Reviewers: sammccall
Reviewed By: sammccall
Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, kadircet, jdoerfert, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D58239
llvm-svn: 354268
Summary:
This adds include-fixer feature into clangd based on D56903. Clangd now captures
diagnostics caused by typos and attach include insertion fixes to potentially
fix the typo.
Reviewers: sammccall
Reviewed By: sammccall
Subscribers: cfe-commits, kadircet, arphaman, mgrang, jkorous, MaskRay, javed.absar, ilya-biryukov, mgorny
Tags: #clang
Differential Revision: https://reviews.llvm.org/D57021
llvm-svn: 353380
Summary:
This enables clangd to intercept compiler diagnostics and attach fixes (e.g. by
querying index). This patch adds missing includes for incomplete types e.g.
member access into class with only forward declaration. This would allow adding
missing includes for user-typed symbol names that are missing declarations
(e.g. typos) in the future.
Reviewers: sammccall
Reviewed By: sammccall
Subscribers: mgorny, ilya-biryukov, javed.absar, MaskRay, jkorous, mgrang, arphaman, kadircet, cfe-commits
Differential Revision: https://reviews.llvm.org/D56903
llvm-svn: 352361
