[clangd] Implement textDocument/hover

Summary: Implemention of textDocument/hover as described in LSP definition.

This patch adds a basic Hover implementation.  When hovering a variable,
function, method or namespace, clangd will return a text containing the
declaration's scope, as well as the declaration of the hovered entity.
For example, for a variable:

  Declared in class Foo::Bar

  int hello = 2

For macros, the macro definition is returned.

This patch doesn't include:

- markdown support (the client I use doesn't support it yet)
- range support (optional in the Hover response)
- comments associated to variables/functions/classes

They are kept as future work to keep this patch simpler.

I added tests in XRefsTests.cpp.  hover.test contains one simple
smoketest to make sure the feature works from a black box perspective.

Reviewers: malaperle, krasimir, bkramer, ilya-biryukov

Subscribers: sammccall, mgrang, klimek, rwols, ilya-biryukov, arphaman, cfe-commits

Differential Revision: https://reviews.llvm.org/D35894

Signed-off-by: Simon Marchi <simon.marchi@ericsson.com>
Signed-off-by: William Enright <william.enright@polymtl.ca>
llvm-svn: 325395

3 files changed, 21 insertions, 0 deletions

diff --git a/clang-tools-extra/test/clangd/hover.test b/clang-tools-extra/test/clangd/hover.test
new file mode 100644
index 00000000000..8ac7a9c2798
--- /dev/null
+++ b/clang-tools-extra/test/clangd/hover.test
@@ -0,0 +1,19 @@
+# RUN: clangd -lit-test < %s | FileCheck %s

+{"jsonrpc":"2.0","id":0,"method":"initialize","params":{"processId":123,"rootPath":"clangd","capabilities":{},"trace":"off"}}

+---

+{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"file:///main.cpp","languageId":"cpp","version":1,"text":"void foo(); int main() { foo(); }\n"}}}

+---

+{"jsonrpc":"2.0","id":1,"method":"textDocument/hover","params":{"textDocument":{"uri":"file:///main.cpp"},"position":{"line":0,"character":27}}}

+#      CHECK:  "id": 1,

+# CHECK-NEXT:  "jsonrpc": "2.0",

+# CHECK-NEXT:  "result": {

+# CHECK-NEXT:    "contents": {

+# CHECK-NEXT:      "kind": "plaintext",

+# CHECK-NEXT:      "value": "Declared in global namespace\n\nvoid foo()"

+# CHECK-NEXT:    }

+# CHECK-NEXT:  }

+# CHECK-NEXT:}

+---

+{"jsonrpc":"2.0","id":3,"method":"shutdown"}

+---

+{"jsonrpc":"2.0","method":"exit"}

diff --git a/clang-tools-extra/test/clangd/initialize-params-invalid.test b/clang-tools-extra/test/clangd/initialize-params-invalid.test
index 1c8d4f0a015..069f3efbd98 100644
--- a/clang-tools-extra/test/clangd/initialize-params-invalid.test
+++ b/clang-tools-extra/test/clangd/initialize-params-invalid.test
@@ -28,6 +28,7 @@
 # CHECK-NEXT:          "clangd.insertInclude"
 # CHECK-NEXT:        ]
 # CHECK-NEXT:      },
+# CHECK-NEXT:      "hoverProvider": true,
 # CHECK-NEXT:      "renameProvider": true,
 # CHECK-NEXT:      "signatureHelpProvider": {
 # CHECK-NEXT:        "triggerCharacters": [
diff --git a/clang-tools-extra/test/clangd/initialize-params.test b/clang-tools-extra/test/clangd/initialize-params.test
index 03eadae871a..cce00ac52ad 100644
--- a/clang-tools-extra/test/clangd/initialize-params.test
+++ b/clang-tools-extra/test/clangd/initialize-params.test
@@ -28,6 +28,7 @@
 # CHECK-NEXT:          "clangd.insertInclude"
 # CHECK-NEXT:        ]
 # CHECK-NEXT:      },
+# CHECK-NEXT:      "hoverProvider": true,
 # CHECK-NEXT:      "renameProvider": true,
 # CHECK-NEXT:      "signatureHelpProvider": {
 # CHECK-NEXT:        "triggerCharacters": [