forked from OSchip/llvm-project
15f3cd6bfc
Without this patch, clang will not wrap in an ElaboratedType node types written without a keyword and nested name qualifier, which goes against the intent that we should produce an AST which retains enough details to recover how things are written. The lack of this sugar is incompatible with the intent of the type printer default policy, which is to print types as written, but to fall back and print them fully qualified when they are desugared. An ElaboratedTypeLoc without keyword / NNS uses no storage by itself, but still requires pointer alignment due to pre-existing bug in the TypeLoc buffer handling. --- Troubleshooting list to deal with any breakage seen with this patch: 1) The most likely effect one would see by this patch is a change in how a type is printed. The type printer will, by design and default, print types as written. There are customization options there, but not that many, and they mainly apply to how to print a type that we somehow failed to track how it was written. This patch fixes a problem where we failed to distinguish between a type that was written without any elaborated-type qualifiers, such as a 'struct'/'class' tags and name spacifiers such as 'std::', and one that has been stripped of any 'metadata' that identifies such, the so called canonical types. Example: ``` namespace foo { struct A {}; A a; }; ``` If one were to print the type of `foo::a`, prior to this patch, this would result in `foo::A`. This is how the type printer would have, by default, printed the canonical type of A as well. As soon as you add any name qualifiers to A, the type printer would suddenly start accurately printing the type as written. This patch will make it print it accurately even when written without qualifiers, so we will just print `A` for the initial example, as the user did not really write that `foo::` namespace qualifier. 2) This patch could expose a bug in some AST matcher. Matching types is harder to get right when there is sugar involved. For example, if you want to match a type against being a pointer to some type A, then you have to account for getting a type that is sugar for a pointer to A, or being a pointer to sugar to A, or both! Usually you would get the second part wrong, and this would work for a very simple test where you don't use any name qualifiers, but you would discover is broken when you do. The usual fix is to either use the matcher which strips sugar, which is annoying to use as for example if you match an N level pointer, you have to put N+1 such matchers in there, beginning to end and between all those levels. But in a lot of cases, if the property you want to match is present in the canonical type, it's easier and faster to just match on that... This goes with what is said in 1), if you want to match against the name of a type, and you want the name string to be something stable, perhaps matching on the name of the canonical type is the better choice. 3) This patch could expose a bug in how you get the source range of some TypeLoc. For some reason, a lot of code is using getLocalSourceRange(), which only looks at the given TypeLoc node. This patch introduces a new, and more common TypeLoc node which contains no source locations on itself. This is not an inovation here, and some other, more rare TypeLoc nodes could also have this property, but if you use getLocalSourceRange on them, it's not going to return any valid locations, because it doesn't have any. The right fix here is to always use getSourceRange() or getBeginLoc/getEndLoc which will dive into the inner TypeLoc to get the source range if it doesn't find it on the top level one. You can use getLocalSourceRange if you are really into micro-optimizations and you have some outside knowledge that the TypeLocs you are dealing with will always include some source location. 4) Exposed a bug somewhere in the use of the normal clang type class API, where you have some type, you want to see if that type is some particular kind, you try a `dyn_cast` such as `dyn_cast<TypedefType>` and that fails because now you have an ElaboratedType which has a TypeDefType inside of it, which is what you wanted to match. Again, like 2), this would usually have been tested poorly with some simple tests with no qualifications, and would have been broken had there been any other kind of type sugar, be it an ElaboratedType or a TemplateSpecializationType or a SubstTemplateParmType. The usual fix here is to use `getAs` instead of `dyn_cast`, which will look deeper into the type. Or use `getAsAdjusted` when dealing with TypeLocs. For some reason the API is inconsistent there and on TypeLocs getAs behaves like a dyn_cast. 5) It could be a bug in this patch perhaps. Let me know if you need any help! Signed-off-by: Matheus Izvekov <mizvekov@gmail.com> Differential Revision: https://reviews.llvm.org/D112374 |
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.. | ||
benchmarks | ||
fuzzer | ||
index | ||
indexer | ||
quality | ||
refactor | ||
support | ||
test | ||
tool | ||
unittests | ||
xpc | ||
AST.cpp | ||
AST.h | ||
ASTSignals.cpp | ||
ASTSignals.h | ||
CMakeLists.txt | ||
ClangdLSPServer.cpp | ||
ClangdLSPServer.h | ||
ClangdServer.cpp | ||
ClangdServer.h | ||
CodeComplete.cpp | ||
CodeComplete.h | ||
CodeCompletionStrings.cpp | ||
CodeCompletionStrings.h | ||
CollectMacros.cpp | ||
CollectMacros.h | ||
CompileCommands.cpp | ||
CompileCommands.h | ||
Compiler.cpp | ||
Compiler.h | ||
Config.cpp | ||
Config.h | ||
ConfigCompile.cpp | ||
ConfigFragment.h | ||
ConfigProvider.cpp | ||
ConfigProvider.h | ||
ConfigYAML.cpp | ||
Diagnostics.cpp | ||
Diagnostics.h | ||
DraftStore.cpp | ||
DraftStore.h | ||
DumpAST.cpp | ||
DumpAST.h | ||
ExpectedTypes.cpp | ||
ExpectedTypes.h | ||
FS.cpp | ||
FS.h | ||
Feature.cpp | ||
Feature.h | ||
FeatureModule.cpp | ||
FeatureModule.h | ||
Features.inc.in | ||
FileDistance.cpp | ||
FileDistance.h | ||
FindSymbols.cpp | ||
FindSymbols.h | ||
FindTarget.cpp | ||
FindTarget.h | ||
Format.cpp | ||
Format.h | ||
FuzzyMatch.cpp | ||
FuzzyMatch.h | ||
GlobalCompilationDatabase.cpp | ||
GlobalCompilationDatabase.h | ||
HeaderSourceSwitch.cpp | ||
HeaderSourceSwitch.h | ||
Headers.cpp | ||
Headers.h | ||
HeuristicResolver.cpp | ||
HeuristicResolver.h | ||
Hover.cpp | ||
Hover.h | ||
IncludeCleaner.cpp | ||
IncludeCleaner.h | ||
IncludeFixer.cpp | ||
IncludeFixer.h | ||
InlayHints.cpp | ||
InlayHints.h | ||
JSONTransport.cpp | ||
LSPBinder.h | ||
ParsedAST.cpp | ||
ParsedAST.h | ||
PathMapping.cpp | ||
PathMapping.h | ||
Preamble.cpp | ||
Preamble.h | ||
Protocol.cpp | ||
Protocol.h | ||
Quality.cpp | ||
Quality.h | ||
QueryDriverDatabase.cpp | ||
README.md | ||
RIFF.cpp | ||
RIFF.h | ||
Selection.cpp | ||
Selection.h | ||
SemanticHighlighting.cpp | ||
SemanticHighlighting.h | ||
SemanticSelection.cpp | ||
SemanticSelection.h | ||
SourceCode.cpp | ||
SourceCode.h | ||
TUScheduler.cpp | ||
TUScheduler.h | ||
TidyProvider.cpp | ||
TidyProvider.h | ||
Transport.h | ||
URI.cpp | ||
URI.h | ||
XRefs.cpp | ||
XRefs.h |
README.md
clangd
clangd is a language server, and provides C++ IDE features to editors. This is not its documentation.
- the website is https://clangd.llvm.org/.
- the bug tracker is https://github.com/clangd/clangd/issues
- the source code is hosted at https://github.com/llvm/llvm-project/tree/main/clang-tools-extra/clangd.
- the website source code is at https://github.com/llvm/clangd-www/
Communication channels
If you have any questions or feedback, you can reach community and developers through one of these channels:
- chat: #clangd room hosted on LLVM's Discord channel.
- user questions and feature requests can be asked in the clangd topic on LLVM Discussion Forums
Building and testing clangd
For a minimal setup on building clangd:
-
Clone the LLVM repo to
$LLVM_ROOT
. -
Create a build directory, for example at
$LLVM_ROOT/build
. -
Inside the build directory run:
cmake $LLVM_ROOT/llvm/ -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_PROJECTS="clang;clang-tools-extra"
.- We suggest building in
Release
mode as building DEBUG binaries requires considerably more resources. You can check Building LLVM with CMake documentation for more details about cmake flags. - In addition to that using
Ninja
as a generator rather than defaultmake
is preferred. To do that consider passing-G Ninja
to cmake invocation. - Finally, you can turn on assertions via
-DLLVM_ENABLE_ASSERTS=On
.
- We suggest building in
-
Afterwards you can build clangd with
cmake --build $LLVM_ROOT/build --target clangd
, similarly run tests by changing target tocheck-clangd
.