[clang-tools-extra] 8513066 - [clangd] Implement LSP 3.17 positionEncoding (#142903)
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Tue Jun 17 10:23:17 PDT 2025
Author: someoneinjd
Date: 2025-06-17T19:23:14+02:00
New Revision: 8513066f2c49457f5d1f63e275403330f854041c
URL: https://github.com/llvm/llvm-project/commit/8513066f2c49457f5d1f63e275403330f854041c
DIFF: https://github.com/llvm/llvm-project/commit/8513066f2c49457f5d1f63e275403330f854041c.diff
LOG: [clangd] Implement LSP 3.17 positionEncoding (#142903)
This PR adds support for the `positionEncoding` client capability
introduced in LSP 3.17. Clangd can now negotiate the position encoding
with the client during initialization.
Fix https://github.com/clangd/clangd/issues/1746
Co-authored-by: kadir çetinkaya <kadircetinkaya.06.tr at gmail.com>
Added:
clang-tools-extra/clangd/test/positionencoding.test
Modified:
clang-tools-extra/clangd/ClangdLSPServer.cpp
clang-tools-extra/clangd/Protocol.cpp
clang-tools-extra/clangd/Protocol.h
Removed:
################################################################################
diff --git a/clang-tools-extra/clangd/ClangdLSPServer.cpp b/clang-tools-extra/clangd/ClangdLSPServer.cpp
index 29321f7cd3fa2..a703009e2b467 100644
--- a/clang-tools-extra/clangd/ClangdLSPServer.cpp
+++ b/clang-tools-extra/clangd/ClangdLSPServer.cpp
@@ -494,9 +494,9 @@ static std::vector<llvm::StringRef> semanticTokenModifiers() {
void ClangdLSPServer::onInitialize(const InitializeParams &Params,
Callback<llvm::json::Value> Reply) {
// Determine character encoding first as it affects constructed ClangdServer.
- if (Params.capabilities.offsetEncoding && !Opts.Encoding) {
+ if (Params.capabilities.PositionEncodings && !Opts.Encoding) {
Opts.Encoding = OffsetEncoding::UTF16; // fallback
- for (OffsetEncoding Supported : *Params.capabilities.offsetEncoding)
+ for (OffsetEncoding Supported : *Params.capabilities.PositionEncodings)
if (Supported != OffsetEncoding::UnsupportedEncoding) {
Opts.Encoding = Supported;
break;
@@ -686,6 +686,9 @@ void ClangdLSPServer::onInitialize(const InitializeParams &Params,
ServerCaps["executeCommandProvider"] =
llvm::json::Object{{"commands", Commands}};
+ if (Opts.Encoding)
+ ServerCaps["positionEncoding"] = *Opts.Encoding;
+
llvm::json::Object Result{
{{"serverInfo",
llvm::json::Object{
@@ -693,6 +696,9 @@ void ClangdLSPServer::onInitialize(const InitializeParams &Params,
{"version", llvm::formatv("{0} {1} {2}", versionString(),
featureString(), platformString())}}},
{"capabilities", std::move(ServerCaps)}}};
+
+ // TODO: offsetEncoding capability is a deprecated clangd extension and should
+ // be deleted.
if (Opts.Encoding)
Result["offsetEncoding"] = *Opts.Encoding;
Reply(std::move(Result));
diff --git a/clang-tools-extra/clangd/Protocol.cpp b/clang-tools-extra/clangd/Protocol.cpp
index c9e8a175b5d76..2c858e28fa243 100644
--- a/clang-tools-extra/clangd/Protocol.cpp
+++ b/clang-tools-extra/clangd/Protocol.cpp
@@ -497,10 +497,19 @@ bool fromJSON(const llvm::json::Value &Params, ClientCapabilities &R,
if (auto Cancel = StaleRequestSupport->getBoolean("cancel"))
R.CancelsStaleRequests = *Cancel;
}
+ if (auto *PositionEncodings = General->get("positionEncodings")) {
+ R.PositionEncodings.emplace();
+ if (!fromJSON(*PositionEncodings, *R.PositionEncodings,
+ P.field("general").field("positionEncodings")))
+ return false;
+ }
}
if (auto *OffsetEncoding = O->get("offsetEncoding")) {
- R.offsetEncoding.emplace();
- if (!fromJSON(*OffsetEncoding, *R.offsetEncoding,
+ R.PositionEncodings.emplace();
+ elog("offsetEncoding capability is a deprecated clangd extension that'll "
+ "go away with clangd 23. Migrate to standard positionEncodings "
+ "capability introduced by LSP 3.17");
+ if (!fromJSON(*OffsetEncoding, *R.PositionEncodings,
P.field("offsetEncoding")))
return false;
}
@@ -536,8 +545,11 @@ bool fromJSON(const llvm::json::Value &Params, ClientCapabilities &R,
}
}
if (auto *OffsetEncoding = Experimental->get("offsetEncoding")) {
- R.offsetEncoding.emplace();
- if (!fromJSON(*OffsetEncoding, *R.offsetEncoding,
+ R.PositionEncodings.emplace();
+ elog("offsetEncoding capability is a deprecated clangd extension that'll "
+ "go away with clangd 23. Migrate to standard positionEncodings "
+ "capability introduced by LSP 3.17");
+ if (!fromJSON(*OffsetEncoding, *R.PositionEncodings,
P.field("offsetEncoding")))
return false;
}
diff --git a/clang-tools-extra/clangd/Protocol.h b/clang-tools-extra/clangd/Protocol.h
index 8a7809d6677ee..3a6bf155ee153 100644
--- a/clang-tools-extra/clangd/Protocol.h
+++ b/clang-tools-extra/clangd/Protocol.h
@@ -528,8 +528,9 @@ struct ClientCapabilities {
/// textDocument.semanticHighlightingCapabilities.semanticHighlighting
bool TheiaSemanticHighlighting = false;
- /// Supported encodings for LSP character offsets. (clangd extension).
- std::optional<std::vector<OffsetEncoding>> offsetEncoding;
+ /// Supported encodings for LSP character offsets.
+ /// general.positionEncodings
+ std::optional<std::vector<OffsetEncoding>> PositionEncodings;
/// The content format that should be used for Hover requests.
/// textDocument.hover.contentEncoding
diff --git a/clang-tools-extra/clangd/test/positionencoding.test b/clang-tools-extra/clangd/test/positionencoding.test
new file mode 100644
index 0000000000000..eea7a1a596e9a
--- /dev/null
+++ b/clang-tools-extra/clangd/test/positionencoding.test
@@ -0,0 +1,32 @@
+# RUN: clangd -lit-test < %s | FileCheck -strict-whitespace %s
+# This test verifies that we can negotiate UTF-8 offsets via the positionEncodings capability introduced in LSP 3.17.
+{"jsonrpc":"2.0","id":0,"method":"initialize","params":{"processId":123,"rootPath":"clangd","capabilities":{"general":{"positionEncodings":["utf-8","utf-16"]}},"trace":"off"}}
+# CHECK: "positionEncoding": "utf-8"
+---
+{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///main.cpp","languageId":"cpp","version":1,"text":"/*ö*/int x;\nint y=x;"}}}
+---
+{"jsonrpc":"2.0","id":1,"method":"textDocument/definition","params":{"textDocument":{"uri":"test:///main.cpp"},"position":{"line":1,"character":6}}}
+# /*ö*/int x;
+# 01234567890
+# x is character (and utf-16) range [9,10) but byte range [10,11).
+# CHECK: "id": 1,
+# CHECK-NEXT: "jsonrpc": "2.0",
+# CHECK-NEXT: "result": [
+# CHECK-NEXT: {
+# CHECK-NEXT: "range": {
+# CHECK-NEXT: "end": {
+# CHECK-NEXT: "character": 11,
+# CHECK-NEXT: "line": 0
+# CHECK-NEXT: },
+# CHECK-NEXT: "start": {
+# CHECK-NEXT: "character": 10,
+# CHECK-NEXT: "line": 0
+# CHECK-NEXT: }
+# CHECK-NEXT: },
+# CHECK-NEXT: "uri": "file://{{.*}}/main.cpp"
+# CHECK-NEXT: }
+# CHECK-NEXT: ]
+---
+{"jsonrpc":"2.0","id":10000,"method":"shutdown"}
+---
+{"jsonrpc":"2.0","method":"exit"}
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