[clang][CodeComplete] Add completion for #embed directive in C23 mode (llvm#165550)

Fixes clangd/clangd#2535

Author: quanzhuo

clang/lib/Sema/SemaCodeComplete.cpp

@@ -10208,6 +10208,24 @@ void SemaCodeCompletion::CodeCompletePreprocessorDirective(bool InConditional) {
   Builder.AddPlaceholderChunk("message");
   Results.AddResult(Builder.TakeString());
 
+  if (getLangOpts().C23) {
+    // #embed "file"
+    Builder.AddTypedTextChunk("embed");
+    Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
+    Builder.AddTextChunk("\"");
+    Builder.AddPlaceholderChunk("file");
+    Builder.AddTextChunk("\"");
+    Results.AddResult(Builder.TakeString());
+
+    // #embed <file>
+    Builder.AddTypedTextChunk("embed");
+    Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
+    Builder.AddTextChunk("<");
+    Builder.AddPlaceholderChunk("file");
+    Builder.AddTextChunk(">");
+    Results.AddResult(Builder.TakeString());
+  }
+
   // Note: #ident and #sccs are such crazy anachronisms that we don't provide
   // completions for them. And __include_macros is a Clang-internal extension
   // that we don't want to encourage anyone to use.

clang/test/Index/complete-preprocessor.m

@@ -80,3 +80,8 @@
 // RUN: env CINDEXTEST_EDITING=1 CINDEXTEST_COMPLETION_CACHING=1 c-index-test -code-completion-at=%s:9:8 %s | FileCheck -check-prefix=CHECK-CC3 %s
 // RUN: env CINDEXTEST_EDITING=1 CINDEXTEST_COMPLETION_CACHING=1 c-index-test -code-completion-at=%s:11:5 %s | FileCheck -check-prefix=CHECK-CC4 %s
 // RUN: env CINDEXTEST_EDITING=1 CINDEXTEST_COMPLETION_CACHING=1 c-index-test -code-completion-at=%s:14:5 %s | FileCheck -check-prefix=CHECK-CC5 %s
+
+// Test #embed completion in C23 mode
+// RUN: c-index-test -code-completion-at=%s:4:2 %s -std=c23 | FileCheck -check-prefix=CHECK-EMBED %s
+// CHECK-EMBED: NotImplemented:{TypedText embed}{HorizontalSpace  }{Text "}{Placeholder file}{Text "} (40)
+// CHECK-EMBED: NotImplemented:{TypedText embed}{HorizontalSpace  }{Text <}{Placeholder file}{Text >} (40)