[PATCH] D49175: [clangd] Ignore sema code complete callback with recovery context.

[Eric Liu via Phabricator via cfe-commits]

ioeric updated this revision to Diff 154979.
ioeric marked 2 inline comments as done.
ioeric added a comment.

- Addressed review comments.


Repository:
  rCTE Clang Tools Extra

https://reviews.llvm.org/D49175

Files:
  clangd/CodeComplete.cpp
  unittests/clangd/CodeCompleteTests.cpp


Index: unittests/clangd/CodeCompleteTests.cpp
===================================================================
--- unittests/clangd/CodeCompleteTests.cpp
+++ unittests/clangd/CodeCompleteTests.cpp
@@ -787,20 +787,24 @@
   EXPECT_THAT(Results.Completions, Contains(Named("X")));
 }
 
-TEST(CompletionTest, CompleteInExcludedPPBranch) {
+TEST(CompletionTest, IgnoreCompleteInExcludedPPBranchWithRecoveryContext) {
   auto Results = completions(R"cpp(
     int bar(int param_in_bar) {
     }
 
     int foo(int param_in_foo) {
 #if 0
+  // In recorvery mode, "param_in_foo" will also be suggested among many other
+  // unrelated symbols; however, this is really a special case where this works.
+  // If the #if block is outside of the function, "param_in_foo" is still
+  // suggested, but "bar" and "foo" are missing. So the recovery mode doesn't
+  // really provide useful results in excluded branches.
   par^
 #endif
     }
 )cpp");
 
-  EXPECT_THAT(Results.Completions, Contains(Labeled("param_in_foo")));
-  EXPECT_THAT(Results.Completions, Not(Contains(Labeled("param_in_bar"))));
+  EXPECT_TRUE(Results.Completions.empty());
 }
 
 SignatureHelp signatures(StringRef Text) {
@@ -1293,6 +1297,18 @@
   EXPECT_EQ(R.detail, "[2 overloads]\n\"foo.h\"");
 }
 
+TEST(CompletionTest, IgnoreRecoveryResults) {
+  auto Results = completions(
+      R"cpp(
+          namespace ns { int NotRecovered() { return 0; } }
+          void f() {
+            // Sema enters recovery mode first and then normal mode.
+            if (auto x = ns::NotRecover^)
+          }
+      )cpp");
+  EXPECT_THAT(Results.Completions, UnorderedElementsAre(Named("NotRecovered")));
+}
+
 } // namespace
 } // namespace clangd
 } // namespace clang
Index: clangd/CodeComplete.cpp
===================================================================
--- clangd/CodeComplete.cpp
+++ clangd/CodeComplete.cpp
@@ -587,6 +587,19 @@
   void ProcessCodeCompleteResults(class Sema &S, CodeCompletionContext Context,
                                   CodeCompletionResult *InResults,
                                   unsigned NumResults) override final {
+    // Results from recovery mode are generally useless, and the callback after
+    // recovery (if any) is usually more interesting. To make sure we handle the
+    // future callback from sema, we just ignore all callbacks in recovery mode,
+    // as taking only results from recovery mode results in poor completion
+    // results.
+    // FIXME: in case there is no future sema completion callback after the
+    // recovery mode, we might still want to provide some results (e.g. trivial
+    // identifier-based completion).
+    if (Context.getKind() == CodeCompletionContext::CCC_Recovery) {
+      log("Code complete: Ignoring sema code complete callback with Recovery "
+          "context.");
+      return;
+    }
     // If a callback is called without any sema result and the context does not
     // support index-based completion, we simply skip it to give way to
     // potential future callbacks with results.


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