And make use of those. These changes are split from prior PR #155028, in order to decrease the size of that PR and facilitate review.
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
Resolves https://github.com/llvm/llvm-project/issues/76208#issuecomment-2830854351 Quoting the docs of `[[clang::flag_enum]]`: https://clang.llvm.org/docs/AttributeReference.html#flag-enum > This attribute can be added to an enumerator to signal to the compiler that it > is intended to be used as a flag type. This will cause the compiler to assume > that the range of the type includes all of the values that you can get by > manipulating bits of the enumerator when issuing warnings. Ideally, we should still check the upper bounds but for simplicity let's not bother for now.
Cleanup most of the lazy-init `BugType` legacy. Some will be preserved, as those are slightly more complicated to refactor. Notice, that the default category for `BugType` is `LogicError`. I omitted setting this explicitly where I could. Please, actually have a look at the diff. I did this manually, and we rarely check the bug type descriptions and stuff in tests, so the testing might be shallow on this one.
The checker EnumCastOutOfRange verifies the (helpful, but not standard-mandated) design rule that integer to enum casts should not produce values that don't have a corresponding enumerator. As it was improved and cleaned up by recent changes, this commit renames it from `alpha.cplusplus.EnumCastOutOfRange` to `optin.core.EnumCastOutOfRange` to reflect that it's no longer alpha quality. As this checker handles a basic language feature (which is also present in plain C), I moved it to a "core" subpackage within "optin". In addition to the renaming, this commit cleans up the documentation in `checkers.rst` and adds the new example code to a test file to ensure that it's indeed producing the behavior claimend in the documentation.
...that is causing the bug report when it's converted to the enum type. This commit only improves the diagnostics and does not affect the set of reports.
EnumCastOutOfRange checker now reports the name of the enum in the warning message. Additionally, a note-tag is placed to highlight the location of the declaration.
...because it provides no useful functionality compared to its base class `BugType`. A long time ago there were substantial differences between `BugType` and `BuiltinBug`, but they were eliminated by commit 1bd58233 in 2009 (!). Since then the only functionality provided by `BuiltinBug` was that it specified `categories::LogicError` as the bug category and it stored an extra data member `desc`. This commit sets `categories::LogicError` as the default value of the third argument (bug category) in the constructors of BugType and replaces use of the `desc` field with simpler logic. Note that `BugType` has a data member `Description` and a non-virtual method `BugType::getDescription()` which queries it; these are distinct from the member `desc` of `BuiltinBug` and the identically named method `BuiltinBug::getDescription()` which queries it. This confusing name collision was a major motivation for the elimination of `BuiltinBug`. As this commit touches many files, I avoided functional changes and left behind FIXME notes to mark minor issues that should be fixed later. Differential Revision: https://reviews.llvm.org/D158855
The alpha.cplusplus.EnumCastOutOfRange checker previously gave many false positives because a warning was given if the initializer value did not appear in the enumerator list. The strict handling caused std::byte to always give a warning, as it is implemented as an enum class without any declarators. Reviewed By: donat.nagy, steakhal Differential Revision: https://reviews.llvm.org/D153954
This patch replaces (llvm::|)Optional< with std::optional<. I'll post a separate patch to remove #include "llvm/ADT/Optional.h". 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