1. Syntax plugin forgets function and adds __builtin_unreachable(); 2. Test modifed to suit updates

Author: Tobi Popoola

clang/examples/PrintTokensSyntax/PrintTokensSyntax.cpp

@@ -30,8 +30,8 @@ class PrintTokensHandler : public SyntaxHandler {
       OS.write_escaped(PP.getSpelling(Tok));
     }
     OS << "\";\n";
-    //write some functions
-    OS << "void doStuff () {\n";
+    // Rewrite syntax original function.
+    OS << getDeclText(PP,D) << "{\n";
     OS << "printf(\"%s\",tokens);\n";
     OS <<"}\n";
   }

clang/include/clang/Parse/Parser.h

@@ -3117,7 +3117,6 @@ class SyntaxHandler {
   std::string Name;
 
   virtual void anchor();
-
 public:
   SyntaxHandler() = default;
   explicit SyntaxHandler(StringRef name) : Name(name) {}
@@ -3128,6 +3127,8 @@ class SyntaxHandler {
                               CachedTokens &Toks,
                               llvm::raw_string_ostream &OS) = 0;
   virtual void AddToPredefines(llvm::raw_string_ostream &OS) = 0;
+  /// Utility function returns actual text of a declarator.
+  StringRef getDeclText(Preprocessor &PP,Declarator &D);
 };
 
 /// Registry of syntax handlers added by plugins

clang/lib/Parse/Parser.cpp

@@ -25,7 +25,14 @@ using namespace clang;
 LLVM_INSTANTIATE_REGISTRY(SyntaxHandlerRegistry)
 
 void SyntaxHandler::anchor() {}
-
+// Utility function returning actual text for a declarrator.
+llvm::StringRef SyntaxHandler::getDeclText(Preprocessor &PP,Declarator &D){
+  auto DeclCharRange = Lexer::getAsCharRange (D.getSourceRange(), 
+		  PP.getSourceManager(), PP.getLangOpts());
+  auto DeclText= Lexer::getSourceText (DeclCharRange,
+		  PP.getSourceManager(), PP.getLangOpts());
+  return DeclText;
+}
 namespace {
 /// A comment handler that passes comments found by the preprocessor
 /// to the parser action.
@@ -1193,9 +1200,10 @@ void Parser::ProcessPluginSyntax(ParsingDeclarator &D) {
 
   std::string Replacement;
   llvm::raw_string_ostream ReplacementOS(Replacement);
-  // Function to be forgotten left empty. Could result to warnings,
-  // possible solution is to user __builtin_unreachable();. 
   ReplacementOS << "\n{\n";
+  // Place __builtin_unreachable(); in the forgotten function. This 
+  // is done to avoid warnings from the compiler.
+  ReplacementOS << "__builtin_unreachable();\n";
   ReplacementOS << "\n}\n";
 
   // Provide the token stream to the plugin and get back the replacement text.

clang/test/Frontend/plugin-syntax-print-tokens.cpp

@@ -13,16 +13,19 @@
 
 //CHECK: define dso_local void @_Z5__fn1v() #0 {
 //CHECK-NEXT: entry:
-//CHECK-NEXT:  ret void
+//CHECK-NEXT:  unreachable
 //CHECK-NEXT: }
 
 
-//CHECK: define dso_local void @_Z7doStuffv() #1 {
+
+//CHECK: define dso_local void @_Z3fn1v() #1 {
 //CHECK-NEXT: entry:
-//CHECK-NEXT:  %0 = load i8*, i8** @_ZL6tokens, align 8
-//CHECK-NEXT:  %call = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str, i64 0, i64 0), i8* %0)
-//CHECK-NEXT:  ret void
+//CHECK-NEXT:   %0 = load i8*, i8** @_ZL6tokens, align 8
+//CHECK-NEXT:   %call = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str, i64 0, i64 0), i8* %0)
+//CHECK-NEXT:   ret void
 //CHECK-NEXT: }
 
 
 
+
+