Change SMRange to be half-open (exclusive end) instead of closed (inclusive)

This is necessary not only for representing empty ranges, but for handling
multibyte characters in the input. (If the end pointer in a range refers to
a multibyte character, should it point to the beginning or the end of the
character in a char array?) Some of the code in the asm parsers was already
assuming this anyway.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171765 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 7 insertions, 5 deletions

diff --git a/include/llvm/Support/SMLoc.h b/include/llvm/Support/SMLoc.h
index 1bf810b4aa..2b0e9dfff7 100644
--- a/include/llvm/Support/SMLoc.h
+++ b/include/llvm/Support/SMLoc.h
@@ -19,7 +19,7 @@
 
 namespace llvm {
 
-/// SMLoc - Represents a location in source code.
+/// Represents a location in source code.
 class SMLoc {
   const char *Ptr;
 public:
@@ -39,9 +39,11 @@ public:
   }
 };
 
-/// SMRange - Represents a range in source code.  Note that unlike standard STL
-/// ranges, the locations specified are considered to be *inclusive*.  For
-/// example, [X,X] *does* include X, it isn't an empty range.
+/// Represents a range in source code.
+///
+/// SMRange is implemented using a half-open range, as is the convention in C++.
+/// In the string "abc", the range (1,3] represents the substring "bc", and the
+/// range (2,2] represents an empty range between the characters "b" and "c".
 class SMRange {
 public:
   SMLoc Start, End;
diff --git a/include/llvm/Support/YAMLParser.h b/include/llvm/Support/YAMLParser.h
index 03cbe33882..5b728bc2b8 100644
--- a/include/llvm/Support/YAMLParser.h
+++ b/include/llvm/Support/YAMLParser.h
@@ -184,7 +184,7 @@ public:
     : Node(NK_Scalar, D, Anchor)
     , Value(Val) {
     SMLoc Start = SMLoc::getFromPointer(Val.begin());
-    SMLoc End = SMLoc::getFromPointer(Val.end() - 1);
+    SMLoc End = SMLoc::getFromPointer(Val.end());
     SourceRange = SMRange(Start, End);
   }