[clang-tidy] Add a Lexer util to get the source text of a statement

[tbourvon]

Summary

This is a simple Lexer util to get the source text of a statement given as parameter. This is needed for D37014.

[aaron.ballman]

clang-tidy/utils/LexerUtils.cpp

39

You should elide the curly braces here.

44

Please don't use auto here, as the type is not spelled out in the initialization.

clang-tidy/utils/LexerUtils.h

26

Formatting (elsewhere as well).

You should run the patch under clang-format to handle this sort of thing.

unittests/clang-tidy/LexerUtilsTest.cpp

31

Don't use auto unless the type is spelled out in the init, such as with dyn_cast

34–35

Can FooLookup.front() actually be null? I think this should use cast<> and assert if given null or something other than a FunctionDecl.

37–38

I think you can use cast<> here instead of dyn_cast_or_null<>, and it will assert for you if the body isn't valid.

43

Spurious newline.

[alexfh]

clang-tidy/utils/LexerUtils.h

26

Have you seen clang::tooling::fixit::getText? It should cover this use case.

[tbourvon]

clang-tidy/utils/LexerUtils.h

26

Hadn't seen that! Seems to be making this whole patch obsolete, I'm closing it

clang-tidy/utils/LexerUtils.h

 namespace tidy {
 namespace utils {
 namespace lexer {
 
 /// Returns previous token or ``tok::unknown`` if not found.
 Token getPreviousToken(const ASTContext &Context, SourceLocation Location,
                        bool SkipComments = true);
 
+/// Get source code text for statement.
+Optional<StringRef> getStmtText(const Stmt* Statement, const SourceManager& SM);
+
 } // namespace lexer
 } // namespace utils
 } // namespace tidy
 } // namespace clang
 
 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_UTILS_LEXER_UTILS_H

clang-tidy/utils/LexerUtils.cpp

if (!Lexer::getRawToken(Location, Token, SourceManager,
         (!SkipComments || !Token.is(tok::comment))) {
       break;
     }
     Location = Location.getLocWithOffset(-1);
   }
   return Token;
 }
 
+Optional<StringRef> getStmtText(const Stmt* Statement, const SourceManager& SM) {
+  if (!Statement) {
+    return llvm::NoneType();
+  }
+
+  bool Error = false;
+  auto Ret = Lexer::getSourceText(
+    CharSourceRange::getTokenRange(Statement->getSourceRange()),
+    SM, LangOptions(),
+    &Error);
+
+  return Error ? llvm::NoneType() : Optional<StringRef>(Ret);
+}
+
 } // namespace lexer
 } // namespace utils
 } // namespace tidy
 } // namespace clang

unittests/clang-tidy/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
   support
   )
 
 get_filename_component(CLANG_LINT_SOURCE_DIR
   ${CMAKE_CURRENT_SOURCE_DIR}/../../clang-tidy REALPATH)
 include_directories(${CLANG_LINT_SOURCE_DIR})
 
 add_extra_unittest(ClangTidyTests
   ClangTidyDiagnosticConsumerTest.cpp
   ClangTidyOptionsTest.cpp
   IncludeInserterTest.cpp
   GoogleModuleTest.cpp
+  LexerUtilsTest.cpp
   LLVMModuleTest.cpp
   NamespaceAliaserTest.cpp
   ObjCModuleTest.cpp
   OverlappingReplacementsTest.cpp
   UsingInserterTest.cpp
   ReadabilityModuleTest.cpp)
 
 target_link_libraries(ClangTidyTests

unittests/clang-tidy/LexerUtilsTest.cpp

+#include "ClangTidyTest.h"
+#include "clang/Tooling/Tooling.h"
+#include "utils/LexerUtils.h"
+#include "gtest/gtest.h"
+
+namespace clang {
+namespace tidy {
+namespace test {
+
+class GetStmtTextTest : public ::testing::Test {
+protected:
+  GetStmtTextTest()
+    : Unit(CheckASTUnitNotNull(tooling::buildASTFromCode("void foo() { int bar = 0; }"))),
+      SM(Unit->getSourceManager())
+  {}
+
+  std::unique_ptr<ASTUnit> CheckASTUnitNotNull(std::unique_ptr<ASTUnit> Unit) {
+    EXPECT_TRUE(Unit);
+    return Unit;
+  }
+
+  std::unique_ptr<ASTUnit> Unit;
+  SourceManager& SM;
+};
+
+TEST_F(GetStmtTextTest, NullStatement) {
+  EXPECT_EQ(llvm::NoneType(), utils::lexer::getStmtText(nullptr, SM));
+}
+
+TEST_F(GetStmtTextTest, SimpleStatement) {
+  auto FooIdent = &Unit->getASTContext().Idents.getOwn("foo");
+  auto FooDeclName = Unit->getASTContext().DeclarationNames.getIdentifier(FooIdent);
+  auto FooLookup = Unit->getASTContext().getTranslationUnitDecl()->lookup(FooDeclName);
+  auto FooFunction = dyn_cast_or_null<FunctionDecl>(FooLookup.front());
+  EXPECT_TRUE(FooFunction);
+
+  auto FooBody = dyn_cast_or_null<CompoundStmt>(FooFunction->getBody());
+  EXPECT_TRUE(FooBody);
+  EXPECT_TRUE(FooBody->body_begin());
+
+  auto DeclStmt = *FooBody->body_begin();
+
+
+  auto Res = utils::lexer::getStmtText(DeclStmt, SM);
+  EXPECT_TRUE(Res.hasValue());
+  EXPECT_EQ("int bar = 0;", *Res);
+}
+
+} // namespace test
+} // namespace tidy
+} // namespace clang