support code snippet completion

Author: FantasqueX

clang/lib/Sema/SemaCodeComplete.cpp

@@ -6753,12 +6753,39 @@ void SemaCodeCompletion::CodeCompleteIfConst(Scope *S) const {
   ResultBuilder Results(SemaRef, CodeCompleter->getAllocator(),
                         CodeCompleter->getCodeCompletionTUInfo(),
                         CodeCompletionContext::CCC_Other);
+  CodeCompletionBuilder Builder(Results.getAllocator(), Results.getCodeCompletionTUInfo());
   Results.EnterNewScope();
   if (getLangOpts().CPlusPlus17) {
-    Results.AddResult(CodeCompletionResult("constexpr"));
+    if (Results.includeCodePatterns()) {
+      Builder.AddTypedTextChunk("constexpr");
+      Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
+      Builder.AddChunk(CodeCompletionString::CK_LeftParen);
+      Builder.AddPlaceholderChunk("condition");
+      Builder.AddChunk(CodeCompletionString::CK_RightParen);
+      Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
+      Builder.AddChunk(CodeCompletionString::CK_LeftBrace);
+      Builder.AddChunk(CodeCompletionString::CK_VerticalSpace);
+      Builder.AddPlaceholderChunk("statements");
+      Builder.AddChunk(CodeCompletionString::CK_VerticalSpace);
+      Builder.AddChunk(CodeCompletionString::CK_RightBrace);
+      Results.AddResult({Builder.TakeString()});
+    } else {
+      Results.AddResult({"constexpr"});
+    }
   }
   if (getLangOpts().CPlusPlus23) {
-    Results.AddResult(CodeCompletionResult("consteval"));
+    if (Results.includeCodePatterns()) {
+      Builder.AddTypedTextChunk("consteval");
+      Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
+      Builder.AddChunk(CodeCompletionString::CK_LeftBrace);
+      Builder.AddChunk(CodeCompletionString::CK_VerticalSpace);
+      Builder.AddPlaceholderChunk("statements");
+      Builder.AddChunk(CodeCompletionString::CK_VerticalSpace);
+      Builder.AddChunk(CodeCompletionString::CK_RightBrace);
+      Results.AddResult({Builder.TakeString()});
+    } else {
+      Results.AddResult({"consteval"});
+    }
   }
   Results.ExitScope();