Use dotted format of version tuple for availability diagnostics

E. g. use "10.11" instead of "10_11".

We are maintaining backward compatibility by parsing underscore-delimited version tuples but no longer keep track of the separator and using dot format for output.

Differential Revision: https://reviews.llvm.org/D46747

rdar://problem/39845032

llvm-svn: 332598
diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index 385d0fb..456214f 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -762,8 +762,10 @@
 ///
 /// version:
 ///   simple-integer
-///   simple-integer ',' simple-integer
-///   simple-integer ',' simple-integer ',' simple-integer
+///   simple-integer '.' simple-integer
+///   simple-integer '_' simple-integer
+///   simple-integer '.' simple-integer '.' simple-integer
+///   simple-integer '_' simple-integer '_' simple-integer
 VersionTuple Parser::ParseVersionTuple(SourceRange &Range) {
   Range = SourceRange(Tok.getLocation(), Tok.getEndLoc());
 
@@ -841,7 +843,7 @@
       return VersionTuple();
     }
 
-    return VersionTuple(Major, Minor, (AfterMajorSeparator == '_'));
+    return VersionTuple(Major, Minor);
   }
 
   const char AfterMinorSeparator = ThisTokBegin[AfterMinor];
@@ -872,7 +874,7 @@
     return VersionTuple();
   }
   ConsumeToken();
-  return VersionTuple(Major, Minor, Subminor, (AfterMajorSeparator == '_'));
+  return VersionTuple(Major, Minor, Subminor);
 }
 
 /// Parse the contents of the "availability" attribute.