added support for -fdiagnostics-format option to SourceMgr class (PR36117)

[kbelochapka]

Summary

in order to facilitate uniform diagnostic message format between clang and llvm,
support was added for -fdiagnostics-format, -fshow-column, -fms-compatibility-version option to SourceMgr class.

this fix consists of two parts, first one for llvm and the second part for clang.
this code review takes care of llvm part, i will create a separate code review for clang.

include/llvm/Support/SourceMgr.h

 public:
   enum DiagKind {
     DK_Error,
     DK_Warning,
     DK_Remark,
     DK_Note,
   };
 
+  enum TextDiagnosticFormat { Clang, MSVC, Vi };
+  TextDiagnosticFormat DiagnosticFormat = TextDiagnosticFormat::Clang;
+  enum MSVCVersion {
+    MSVC40 = 1000,
+    MSVC97 = 1100,
+    MSVC60 = 1200,
+    MSVC2002 = 1300,
+    MSVC2003 = 1310,
+    MSVC2005 = 1400,
+    MSVC2008 = 1500,
+    MSVC2010 = 1600,
+    MSVC2012 = 1700,
+    MSVC2013 = 1800,
+    MSVC2015 = 1900,
+    MSVC2017 = 1910
+  };
+  MSVCVersion MsvcVersion = MSVCVersion::MSVC2017;
+  bool ShowColumn = true;
+
   /// Clients that want to handle their own diagnostics in a custom way can
   /// register a function pointer+context as a diagnostic handler.
   /// It gets called each time PrintMessage is invoked.
   using DiagHandlerTy = void (*)(const SMDiagnostic &, void *Context);
 
 private:
   struct SrcBuffer {
     /// The memory buffer for the file.
class SMDiagnostic {
   std::string Filename;
   int LineNo = 0;
   int ColumnNo = 0;
   SourceMgr::DiagKind Kind = SourceMgr::DK_Error;
   std::string Message, LineContents;
   std::vector<std::pair<unsigned, unsigned>> Ranges;
   SmallVector<SMFixIt, 4> FixIts;
 
+  SourceMgr::TextDiagnosticFormat DiagnosticFormat =
+      SourceMgr::TextDiagnosticFormat::Clang;
+  SourceMgr::MSVCVersion MsvcVersion = SourceMgr::MSVCVersion::MSVC2017;
+  bool ShowColumn = true;
+
 public:
   // Null diagnostic.
   SMDiagnostic() = default;
   // Diagnostic with no location (e.g. file not found, command line arg error).
   SMDiagnostic(StringRef filename, SourceMgr::DiagKind Knd, StringRef Msg)
     : Filename(filename), LineNo(-1), ColumnNo(-1), Kind(Knd), Message(Msg) {}
 
   // Diagnostic with a location.

lib/Support/SourceMgr.cpp

void SourceMgr::PrintMessage(SMLoc Loc, SourceMgr::DiagKind Kind,
                              ArrayRef<SMFixIt> FixIts, bool ShowColors) const {
   PrintMessage(errs(), Loc, Kind, Msg, Ranges, FixIts, ShowColors);
 }
 
 //===----------------------------------------------------------------------===//
 // SMDiagnostic Implementation
 //===----------------------------------------------------------------------===//
 
-SMDiagnostic::SMDiagnostic(const SourceMgr &sm, SMLoc L, StringRef FN,
-                           int Line, int Col, SourceMgr::DiagKind Kind,
-                           StringRef Msg, StringRef LineStr,
-                           ArrayRef<std::pair<unsigned,unsigned>> Ranges,
+SMDiagnostic::SMDiagnostic(const SourceMgr &sm, SMLoc L, StringRef FN, int Line,
+                           int Col, SourceMgr::DiagKind Kind, StringRef Msg,
+                           StringRef LineStr,
+                           ArrayRef<std::pair<unsigned, unsigned>> Ranges,
                            ArrayRef<SMFixIt> Hints)
     : SM(&sm), Loc(L), Filename(FN), LineNo(Line), ColumnNo(Col), Kind(Kind),
       Message(Msg), LineContents(LineStr), Ranges(Ranges.vec()),
-    FixIts(Hints.begin(), Hints.end()) {
+      FixIts(Hints.begin(), Hints.end()), DiagnosticFormat(sm.DiagnosticFormat),
+      MsvcVersion(sm.MsvcVersion), ShowColumn(sm.ShowColumn) {
   std::sort(FixIts.begin(), FixIts.end());
 }
 
 static void buildFixItLine(std::string &CaretLine, std::string &FixItLine,
                            ArrayRef<SMFixIt> FixIts, ArrayRef<char> SourceLine){
   if (FixIts.empty())
     return;
 
if (ProgName && ProgName[0])
     S << ProgName << ": ";
 
   if (!Filename.empty()) {
     if (Filename == "-")
       S << "<stdin>";
     else
       S << Filename;
 
+    if (!SM) {
       if (LineNo != -1) {
         S << ':' << LineNo;
         if (ColumnNo != -1)
-        S << ':' << (ColumnNo+1);
+          S << ':' << (ColumnNo + 1);
       }
+    } else if (LineNo != -1) {
+      switch (DiagnosticFormat) {
+      default:
+      case SourceMgr::TextDiagnosticFormat::Clang:
+        S << ':' << LineNo;
+        break;
+      case SourceMgr::TextDiagnosticFormat::MSVC:
+        S << '(' << LineNo;
+        break;
+      case SourceMgr::TextDiagnosticFormat::Vi:
+        S << " +" << LineNo;
+        break;
+      }
+      if (ShowColumn && (ColumnNo != -1)) {
+        int ColumnNoOffs = 0;
+        if (DiagnosticFormat == SourceMgr::TextDiagnosticFormat::MSVC) {
+          S << ',';
+          // Visual Studio 2010 or earlier expects column number to be off by
+          // one
+          if (MsvcVersion <= SourceMgr::MSVCVersion::MSVC2010)
+            ColumnNoOffs = 1;
+        } else
+          S << ':';
+        S << ((ColumnNo + 1) - ColumnNoOffs);
+      }
+      switch (DiagnosticFormat) {
+      default:
+      case SourceMgr::TextDiagnosticFormat::Clang:
+      case SourceMgr::TextDiagnosticFormat::Vi:
         S << ": ";
+        break;
+      case SourceMgr::TextDiagnosticFormat::MSVC:
+        // MSVC2013 and before print 'file(4) : error'. MSVC2015 gets rid of the
+        // space and prints 'file(4): error'.
+        if (MsvcVersion < SourceMgr::MSVCVersion::MSVC2015)
+          S << ") : ";
+        else
+          S << "): ";
+        break;
+      }
+    } else {
+      S << ": ";
+    }
   }
 
   if (ShowKindLabel) {
     switch (Kind) {
     case SourceMgr::DK_Error:
       if (ShowColors)
         S.changeColor(raw_ostream::RED, true);
       S << "error: ";