Make tooling::applyAllReplacements return llvm::Expected<string> instead of empty string to indicate potential error.

Summary:
return llvm::Expected<> to carry error status and error information.
This is the first step towards introducing "Error" into tooling::Replacements.

Reviewers: djasper, klimek

Subscribers: ioeric, klimek, cfe-commits

Differential Revision: http://reviews.llvm.org/D21601

llvm-svn: 275062

2 files changed, 13 insertions, 5 deletions

diff --git a/clang/lib/Tooling/Core/Replacement.cpp b/clang/lib/Tooling/Core/Replacement.cpp
index d52d0b08985..4f130709ac1 100644
--- a/clang/lib/Tooling/Core/Replacement.cpp
+++ b/clang/lib/Tooling/Core/Replacement.cpp
@@ -249,8 +249,10 @@ bool applyAllReplacements(const std::vector<Replacement> &Replaces,
   return Result;
 }
 
-std::string applyAllReplacements(StringRef Code, const Replacements &Replaces) {
-  if (Replaces.empty()) return Code;
+llvm::Expected<std::string> applyAllReplacements(StringRef Code,
+                                                const Replacements &Replaces) {
+  if (Replaces.empty())
+    return Code.str();
 
   IntrusiveRefCntPtr<vfs::InMemoryFileSystem> InMemoryFileSystem(
       new vfs::InMemoryFileSystem);
@@ -269,7 +271,9 @@ std::string applyAllReplacements(StringRef Code, const Replacements &Replaces) {
     Replacement Replace("<stdin>", I->getOffset(), I->getLength(),
                         I->getReplacementText());
     if (!Replace.apply(Rewrite))
-      return "";
+      return llvm::make_error<llvm::StringError>(
+          "Failed to apply replacement: " + Replace.toString(),
+          llvm::inconvertibleErrorCode());
   }
   std::string Result;
   llvm::raw_string_ostream OS(Result);
diff --git a/clang/lib/Tooling/Refactoring.cpp b/clang/lib/Tooling/Refactoring.cpp
index 51f0635c1ec..28d535aeb45 100644
--- a/clang/lib/Tooling/Refactoring.cpp
+++ b/clang/lib/Tooling/Refactoring.cpp
@@ -79,9 +79,13 @@ bool formatAndApplyAllReplacements(const Replacements &Replaces,
     StringRef Code = SM.getBufferData(ID);
 
     format::FormatStyle CurStyle = format::getStyle(Style, FilePath, "LLVM");
-    Replacements NewReplacements =
+    auto NewReplacements =
         format::formatReplacements(Code, CurReplaces, CurStyle);
-    Result = applyAllReplacements(NewReplacements, Rewrite) && Result;
+    if (!NewReplacements) {
+      llvm::errs() << llvm::toString(NewReplacements.takeError()) << "\n";
+      return false;
+    }
+    Result = applyAllReplacements(*NewReplacements, Rewrite) && Result;
   }
   return Result;
 }