[clangd] Implement "textDocument/documentLink" protocol support

Summary:
This adds an implementation for the "textDocument/documentLink" LSP request.

It returns links for all `#include` directives to the resolved target files.

Fixes https://github.com/clangd/clangd/issues/217.

Reviewers: sammccall

Reviewed By: sammccall

Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, kadircet, usaxena95, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D70872

1 files changed, 21 insertions, 0 deletions

diff --git a/clang-tools-extra/clangd/unittests/XRefsTests.cpp b/clang-tools-extra/clangd/unittests/XRefsTests.cpp
index e009c1c3ab2..058f205bb3a 100644
--- a/clang-tools-extra/clangd/unittests/XRefsTests.cpp
+++ b/clang-tools-extra/clangd/unittests/XRefsTests.cpp
@@ -1048,6 +1048,27 @@ TEST(GetNonLocalDeclRefs, All) {
   }
 }
 
+TEST(DocumentLinks, All) {
+  Annotations MainCpp(R"cpp(
+      #include $foo[["foo.h"]]
+      int end_of_preamble = 0;
+      #include $bar[["bar.h"]]
+    )cpp");
+
+  TestTU TU;
+  TU.Code = MainCpp.code();
+  TU.AdditionalFiles = {{"foo.h", ""}, {"bar.h", ""}};
+  auto AST = TU.build();
+
+  EXPECT_THAT(
+      clangd::getDocumentLinks(AST),
+      ElementsAre(
+          DocumentLink({MainCpp.range("foo"),
+                        URIForFile::canonicalize(testPath("foo.h"), "")}),
+          DocumentLink({MainCpp.range("bar"),
+                        URIForFile::canonicalize(testPath("bar.h"), "")})));
+}
+
 } // namespace
 } // namespace clangd
 } // namespace clang