Add back support for a manually formatted section of the diagnostic

message. Specifically, we now only line-wrap the first line of te
diagnostic message and assume the remainder is manually formatted. While
adding it back, simplify the logic for doing this.

Finally, add a test that ensures we actually preserve this feature. =D
*Now* its not dead code. Thanks to Doug for the test case.

llvm-svn: 140538

clang/lib/Frontend/TextDiagnosticPrinter.cpp

@@ -1097,7 +1097,7 @@ static bool printWordWrapped(raw_ostream &OS, StringRef Str,
                              unsigned Columns,
                              unsigned Column = 0,
                              unsigned Indentation = WordWrapIndentation) {
-  const unsigned Length = Str.size();
+  const unsigned Length = std::min(Str.find('\n'), Str.size());
 
   // The string used to indent each line.
   llvm::SmallString<16> IndentStr;
@@ -1135,6 +1135,9 @@ static bool printWordWrapped(raw_ostream &OS, StringRef Str,
     Wrapped = true;
   }
 
+  // Append any remaning text from the message with its existing formatting.
+  OS << Str.substr(Length);
+
   return Wrapped;
 }
 

clang/test/Misc/diag-line-wrapping.cpp

@@ -0,0 +1,13 @@
+// RUN: %clang_cc1 -fsyntax-only -fmessage-length 60 %s 2>&1 | FileCheck %s
+
+struct B { void f(); };
+struct D1 : B {};
+struct D2 : B {};
+struct DD : D1, D2 {
+  void g() { f(); }
+  // Ensure that after line-wrapping takes place, we preserve artificial
+  // newlines introduced to manually format a section of the diagnostic text.
+  // CHECK: {{.*}}: error:
+  // CHECK: struct DD -> struct D1 -> struct B
+  // CHECK: struct DD -> struct D2 -> struct B
+}