https://github.com/JaagupAverin created
https://github.com/llvm/llvm-project/pull/155105
Currently macro expansions are hard capped at 2048. This PR adds the CLI option
`--limit-hover-contents` which is passed down in place of the hard coded value.
Resolves #153355.
>From 82c5665913eca5c63c952df93df27d9875596dea Mon Sep 17 00:00:00 2001
From: JaagupA <jaagup.ave...@gmail.com>
Date: Sat, 23 Aug 2025 16:14:35 +0300
Subject: [PATCH] [clangd] Add option: limit-hover-contents
Resolves #153355.
---
clang-tools-extra/clangd/ClangdLSPServer.cpp | 1 +
clang-tools-extra/clangd/ClangdLSPServer.h | 3 ++
clang-tools-extra/clangd/ClangdServer.cpp | 6 ++-
clang-tools-extra/clangd/ClangdServer.h | 2 +-
clang-tools-extra/clangd/Hover.cpp | 9 +++--
clang-tools-extra/clangd/Hover.h | 9 +++--
clang-tools-extra/clangd/tool/Check.cpp | 2 +-
clang-tools-extra/clangd/tool/ClangdMain.cpp | 10 +++++
.../clangd/unittests/HoverTests.cpp | 40 +++++++++++++++++++
9 files changed, 71 insertions(+), 11 deletions(-)
diff --git a/clang-tools-extra/clangd/ClangdLSPServer.cpp
b/clang-tools-extra/clangd/ClangdLSPServer.cpp
index b445dcf2bbd2e..503935a0a4797 100644
--- a/clang-tools-extra/clangd/ClangdLSPServer.cpp
+++ b/clang-tools-extra/clangd/ClangdLSPServer.cpp
@@ -1268,6 +1268,7 @@ void ClangdLSPServer::onDocumentHighlight(
void ClangdLSPServer::onHover(const TextDocumentPositionParams &Params,
Callback<std::optional<Hover>> Reply) {
Server->findHover(Params.textDocument.uri.file(), Params.position,
+ Opts.HoverContentsLimit,
[Reply = std::move(Reply),
this](llvm::Expected<std::optional<HoverInfo>> H) mutable
{
if (!H)
diff --git a/clang-tools-extra/clangd/ClangdLSPServer.h
b/clang-tools-extra/clangd/ClangdLSPServer.h
index 6ada3fd9e6e47..7c2c44fea1b4a 100644
--- a/clang-tools-extra/clangd/ClangdLSPServer.h
+++ b/clang-tools-extra/clangd/ClangdLSPServer.h
@@ -64,6 +64,9 @@ class ClangdLSPServer : private ClangdServer::Callbacks,
/// Limit the number of references returned (0 means no limit).
size_t ReferencesLimit = 0;
+ /// Limit the number of characters returned when hovering a symbol.
+ size_t HoverContentsLimit = 0;
+
/// Flag to hint the experimental modules support is enabled.
bool EnableExperimentalModulesSupport = false;
};
diff --git a/clang-tools-extra/clangd/ClangdServer.cpp
b/clang-tools-extra/clangd/ClangdServer.cpp
index ac1e9aa5f0ff1..01ec164a56e59 100644
--- a/clang-tools-extra/clangd/ClangdServer.cpp
+++ b/clang-tools-extra/clangd/ClangdServer.cpp
@@ -843,14 +843,16 @@ void ClangdServer::findDocumentHighlights(
}
void ClangdServer::findHover(PathRef File, Position Pos,
+ size_t HoverContentsLimit,
Callback<std::optional<HoverInfo>> CB) {
- auto Action = [File = File.str(), Pos, CB = std::move(CB),
+ auto Action = [File = File.str(), Pos, HoverContentsLimit, CB =
std::move(CB),
this](llvm::Expected<InputsAndAST> InpAST) mutable {
if (!InpAST)
return CB(InpAST.takeError());
format::FormatStyle Style = getFormatStyleForFile(
File, InpAST->Inputs.Contents, *InpAST->Inputs.TFS, false);
- CB(clangd::getHover(InpAST->AST, Pos, std::move(Style), Index));
+ CB(clangd::getHover(InpAST->AST, Pos, std::move(Style), Index,
+ HoverContentsLimit));
};
WorkScheduler->runWithAST("Hover", File, std::move(Action), Transient);
diff --git a/clang-tools-extra/clangd/ClangdServer.h
b/clang-tools-extra/clangd/ClangdServer.h
index 4a1eae188f7eb..6a3fa55d1fcc3 100644
--- a/clang-tools-extra/clangd/ClangdServer.h
+++ b/clang-tools-extra/clangd/ClangdServer.h
@@ -270,7 +270,7 @@ class ClangdServer {
Callback<std::vector<DocumentHighlight>> CB);
/// Get code hover for a given position.
- void findHover(PathRef File, Position Pos,
+ void findHover(PathRef File, Position Pos, size_t HoverContentsLimit,
Callback<std::optional<HoverInfo>> CB);
/// Get information about type hierarchy for a given position.
diff --git a/clang-tools-extra/clangd/Hover.cpp
b/clang-tools-extra/clangd/Hover.cpp
index a7cf45c632827..f352a16c12ecb 100644
--- a/clang-tools-extra/clangd/Hover.cpp
+++ b/clang-tools-extra/clangd/Hover.cpp
@@ -755,7 +755,7 @@ HoverInfo evaluateMacroExpansion(unsigned int
SpellingBeginOffset,
/// Generate a \p Hover object given the macro \p MacroDecl.
HoverInfo getHoverContents(const DefinedMacro &Macro, const syntax::Token &Tok,
- ParsedAST &AST) {
+ ParsedAST &AST, size_t HoverContentsLimit) {
HoverInfo HI;
SourceManager &SM = AST.getSourceManager();
HI.Name = std::string(Macro.Name);
@@ -795,7 +795,7 @@ HoverInfo getHoverContents(const DefinedMacro &Macro, const
syntax::Token &Tok,
for (const auto &ExpandedTok : Expansion->Expanded) {
ExpansionText += ExpandedTok.text(SM);
ExpansionText += " ";
- if (ExpansionText.size() > 2048) {
+ if (HoverContentsLimit && ExpansionText.size() > HoverContentsLimit) {
ExpansionText.clear();
break;
}
@@ -1250,7 +1250,8 @@ void maybeAddUsedSymbols(ParsedAST &AST, HoverInfo &HI,
const Inclusion &Inc) {
std::optional<HoverInfo> getHover(ParsedAST &AST, Position Pos,
const format::FormatStyle &Style,
- const SymbolIndex *Index) {
+ const SymbolIndex *Index,
+ size_t HoverContentsLimit) {
static constexpr trace::Metric HoverCountMetric(
"hover", trace::Metric::Counter, "case");
PrintingPolicy PP =
@@ -1297,7 +1298,7 @@ std::optional<HoverInfo> getHover(ParsedAST &AST,
Position Pos,
HighlightRange = Tok.range(SM).toCharRange(SM);
if (auto M = locateMacroAt(Tok, AST.getPreprocessor())) {
HoverCountMetric.record(1, "macro");
- HI = getHoverContents(*M, Tok, AST);
+ HI = getHoverContents(*M, Tok, AST, HoverContentsLimit);
if (auto DefLoc = M->Info->getDefinitionLoc(); DefLoc.isValid()) {
include_cleaner::Macro IncludeCleanerMacro{
AST.getPreprocessor().getIdentifierInfo(Tok.text(SM)), DefLoc};
diff --git a/clang-tools-extra/clangd/Hover.h b/clang-tools-extra/clangd/Hover.h
index 614180a7b9846..4dbd7c050421d 100644
--- a/clang-tools-extra/clangd/Hover.h
+++ b/clang-tools-extra/clangd/Hover.h
@@ -163,10 +163,13 @@ inline bool operator==(const HoverInfo::Param &LHS,
std::tie(RHS.Type, RHS.Name, RHS.Default);
}
+constexpr size_t DefaultHoverContentsLimit = 2048;
+
/// Get the hover information when hovering at \p Pos.
-std::optional<HoverInfo> getHover(ParsedAST &AST, Position Pos,
- const format::FormatStyle &Style,
- const SymbolIndex *Index);
+std::optional<HoverInfo>
+getHover(ParsedAST &AST, Position Pos, const format::FormatStyle &Style,
+ const SymbolIndex *Index,
+ size_t HoverContentsLimit = DefaultHoverContentsLimit);
} // namespace clangd
} // namespace clang
diff --git a/clang-tools-extra/clangd/tool/Check.cpp
b/clang-tools-extra/clangd/tool/Check.cpp
index df8d075e80596..d103ef3f5aed3 100644
--- a/clang-tools-extra/clangd/tool/Check.cpp
+++ b/clang-tools-extra/clangd/tool/Check.cpp
@@ -441,7 +441,7 @@ class Checker {
unsigned Definitions = locateSymbolAt(*AST, Pos, &Index).size();
vlog(" definition: {0}", Definitions);
- auto Hover = getHover(*AST, Pos, Style, &Index);
+ auto Hover = getHover(*AST, Pos, Style, &Index, Opts.HoverContentsLimit);
vlog(" hover: {0}", Hover.has_value());
unsigned DocHighlights = findDocumentHighlights(*AST, Pos).size();
diff --git a/clang-tools-extra/clangd/tool/ClangdMain.cpp
b/clang-tools-extra/clangd/tool/ClangdMain.cpp
index f287439f10cab..5e8755d643d7f 100644
--- a/clang-tools-extra/clangd/tool/ClangdMain.cpp
+++ b/clang-tools-extra/clangd/tool/ClangdMain.cpp
@@ -328,6 +328,15 @@ opt<int> ReferencesLimit{
init(1000),
};
+opt<int> HoverContentsLimit{
+ "limit-hover-contents",
+ cat(Features),
+ desc("Limit the number of characters returned when hovering a symbol. "
+ "Texts longer than this value will be dropped (not truncated). "
+ "0 means no limit (default=2048)"),
+ init(DefaultHoverContentsLimit),
+};
+
opt<int> RenameFileLimit{
"rename-file-limit",
cat(Features),
@@ -925,6 +934,7 @@ clangd accepts flags on the commandline, and in the
CLANGD_FLAGS environment var
Opts.BackgroundIndex = EnableBackgroundIndex;
Opts.BackgroundIndexPriority = BackgroundIndexPriority;
Opts.ReferencesLimit = ReferencesLimit;
+ Opts.HoverContentsLimit = HoverContentsLimit;
Opts.Rename.LimitFiles = RenameFileLimit;
auto PAI = createProjectAwareIndex(
[SupportContainedRefs = Opts.EnableOutgoingCalls](
diff --git a/clang-tools-extra/clangd/unittests/HoverTests.cpp
b/clang-tools-extra/clangd/unittests/HoverTests.cpp
index 6407349d9af9b..fe0f4334746ca 100644
--- a/clang-tools-extra/clangd/unittests/HoverTests.cpp
+++ b/clang-tools-extra/clangd/unittests/HoverTests.cpp
@@ -4461,6 +4461,46 @@ constexpr u64 pow_with_mod(u64 a, u64 b, u64 p) {
EXPECT_TRUE(H->Type);
}
+TEST(Hover, HoverContentsLimit) {
+ const char *const Code =
+ R"cpp(
+ #define C(A) A##A // Concatenate
+ #define E(A) C(A) // Expand
+ #define Z0032 00000000000000000000000000000000
+ #define Z0064 E(Z0032)
+ #define Z0128 E(Z0064)
+ #define Z0256 E(Z0128)
+ #define Z0512 E(Z0256)
+ #define Z1024 E(Z0512)
+ #define Z2048 E(Z1024)
+ #define Z4096 E(Z2048) // 4096 zeroes
+ int main() { return [[^Z4096]]; }
+ )cpp";
+
+ struct {
+ size_t HoverContentsLimit;
+ const std::string ExpectedDefinition;
+ } Cases[] = {
+ // With a limit of 2048, the macro expansion should get dropped.
+ {2048, "#define Z4096 E(Z2048)"},
+ // With a limit of 8192, the macro expansion should be fully expanded.
+ {8192, std::string("#define Z4096 E(Z2048)\n\n") +
+ std::string("// Expands to\n") + std::string(4096, '0')},
+ };
+ for (const auto &Case : Cases) {
+ SCOPED_TRACE(Code);
+
+ Annotations T(Code);
+ TestTU TU = TestTU::withCode(T.code());
+ auto AST = TU.build();
+ auto H = getHover(AST, T.point(), format::getLLVMStyle(), nullptr,
+ Case.HoverContentsLimit);
+ ASSERT_TRUE(H);
+
+ EXPECT_EQ(H->Definition, Case.ExpectedDefinition);
+ }
+};
+
TEST(Hover, FunctionParameters) {
struct {
const char *const Code;
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