[llvm-branch-commits] [clang-tools-extra] db68723 - [clangd] Return earlier when snippet is empty

[Tobias Hieta via llvm-branch-commits]

Author: Tom Praschan
Date: 2022-10-25T09:37:35+02:00
New Revision: db68723804fd30d5e7da1fb2ad2aab409ef58d29

URL: https://github.com/llvm/llvm-project/commit/db68723804fd30d5e7da1fb2ad2aab409ef58d29
DIFF: https://github.com/llvm/llvm-project/commit/db68723804fd30d5e7da1fb2ad2aab409ef58d29.diff

LOG: [clangd] Return earlier when snippet is empty

Fixes github.com/clangd/clangd/issues/1216

If the Snippet string is empty, Snippet.front() would trigger a crash.
Move the Snippet->empty() check up a few lines to avoid this. Should not
break any existing behavior.

Differential Revision: https://reviews.llvm.org/D134137

(cherry picked from commit 60528c690a4c334d2a3a2c22eb97af9e67d7a91d)

Added: 
    

Modified: 
    clang-tools-extra/clangd/CodeComplete.cpp
    clang-tools-extra/clangd/unittests/CodeCompleteTests.cpp

Removed: 
    


################################################################################
diff  --git a/clang-tools-extra/clangd/CodeComplete.cpp b/clang-tools-extra/clangd/CodeComplete.cpp
index edbb1722ae38e..55982f41250f5 100644
--- a/clang-tools-extra/clangd/CodeComplete.cpp
+++ b/clang-tools-extra/clangd/CodeComplete.cpp
@@ -486,6 +486,9 @@ struct CodeCompletionBuilder {
       // we need to complete 'forward<$1>($0)'.
       return "($0)";
 
+    if (Snippet->empty())
+      return "";
+
     bool MayHaveArgList = Completion.Kind == CompletionItemKind::Function ||
                           Completion.Kind == CompletionItemKind::Method ||
                           Completion.Kind == CompletionItemKind::Constructor ||
@@ -524,8 +527,6 @@ struct CodeCompletionBuilder {
       return *Snippet;
 
     // Replace argument snippets with a simplified pattern.
-    if (Snippet->empty())
-      return "";
     if (MayHaveArgList) {
       // Functions snippets can be of 2 types:
       // - containing only function arguments, e.g.

diff  --git a/clang-tools-extra/clangd/unittests/CodeCompleteTests.cpp b/clang-tools-extra/clangd/unittests/CodeCompleteTests.cpp
index 5050ab203b8db..079a4ec70623c 100644
--- a/clang-tools-extra/clangd/unittests/CodeCompleteTests.cpp
+++ b/clang-tools-extra/clangd/unittests/CodeCompleteTests.cpp
@@ -1014,6 +1014,23 @@ TEST(CodeCompleteTest, NoColonColonAtTheEnd) {
   EXPECT_THAT(Results.Completions, Not(Contains(labeled("clang::"))));
 }
 
+TEST(CompletionTests, EmptySnippetDoesNotCrash) {
+    // See https://github.com/clangd/clangd/issues/1216
+    auto Results = completions(R"cpp(
+        int main() {
+          auto w = [&](auto &&f) { return f(f); };
+          auto f = w([&](auto &&f) {
+            return [&](auto &&n) {
+              if (n == 0) {
+                return 1;
+              }
+              return n * ^(f)(n - 1);
+            };
+          })(10);
+        }
+    )cpp");
+}
+
 TEST(CompletionTest, BacktrackCrashes) {
   // Sema calls code completion callbacks twice in these cases.
   auto Results = completions(R"cpp(