Add a fix-it for -Wunguarded-availability

This patch adds a fix-it for the -Wunguarded-availability warning. This fix-it
is similar to the Swift one: it suggests that you wrap the statement in an
`if (@available)` check. The produced fixits are indented (just like the Swift
ones) to make them look nice in Xcode's fix-it preview.

rdar://31680358

Differential Revision: https://reviews.llvm.org/D32424


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@302253 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 49 insertions, 17 deletions

diff --git a/lib/Lex/Lexer.cpp b/lib/Lex/Lexer.cpp
index 003c9b5eed..3d6fe91115 100644
--- a/lib/Lex/Lexer.cpp
+++ b/lib/Lex/Lexer.cpp
@@ -452,6 +452,29 @@ bool Lexer::getRawToken(SourceLocation Loc, Token &Result,
   return false;
 }
 
+/// Returns the pointer that points to the beginning of line that contains
+/// the given offset, or null if the offset if invalid.
+static const char *findBeginningOfLine(StringRef Buffer, unsigned Offset) {
+  const char *BufStart = Buffer.data();
+  if (Offset >= Buffer.size())
+    return nullptr;
+  const char *StrData = BufStart + Offset;
+
+  if (StrData[0] == '\n' || StrData[0] == '\r')
+    return StrData;
+
+  const char *LexStart = StrData;
+  while (LexStart != BufStart) {
+    if (LexStart[0] == '\n' || LexStart[0] == '\r') {
+      ++LexStart;
+      break;
+    }
+
+    --LexStart;
+  }
+  return LexStart;
+}
+
 static SourceLocation getBeginningOfFileToken(SourceLocation Loc,
                                               const SourceManager &SM,
                                               const LangOptions &LangOpts) {
@@ -467,27 +490,15 @@ static SourceLocation getBeginningOfFileToken(SourceLocation Loc,
 
   // Back up from the current location until we hit the beginning of a line
   // (or the buffer). We'll relex from that point.
-  const char *BufStart = Buffer.data();
-  if (LocInfo.second >= Buffer.size())
-    return Loc;
-  
-  const char *StrData = BufStart+LocInfo.second;
-  if (StrData[0] == '\n' || StrData[0] == '\r')
+  const char *StrData = Buffer.data() + LocInfo.second;
+  const char *LexStart = findBeginningOfLine(Buffer, LocInfo.second);
+  if (!LexStart || LexStart == StrData)
     return Loc;
-
-  const char *LexStart = StrData;
-  while (LexStart != BufStart) {
-    if (LexStart[0] == '\n' || LexStart[0] == '\r') {
-      ++LexStart;
-      break;
-    }
-
-    --LexStart;
-  }
   
   // Create a lexer starting at the beginning of this token.
   SourceLocation LexerStartLoc = Loc.getLocWithOffset(-LocInfo.second);
-  Lexer TheLexer(LexerStartLoc, LangOpts, BufStart, LexStart, Buffer.end());
+  Lexer TheLexer(LexerStartLoc, LangOpts, Buffer.data(), LexStart,
+                 Buffer.end());
   TheLexer.SetCommentRetentionState(true);
   
   // Lex tokens until we find the token that contains the source location.
@@ -1038,6 +1049,27 @@ bool Lexer::isIdentifierBodyChar(char c, const LangOptions &LangOpts) {
   return isIdentifierBody(c, LangOpts.DollarIdents);
 }
 
+StringRef Lexer::getIndentationForLine(SourceLocation Loc,
+                                       const SourceManager &SM) {
+  if (Loc.isInvalid() || Loc.isMacroID())
+    return "";
+  std::pair<FileID, unsigned> LocInfo = SM.getDecomposedLoc(Loc);
+  if (LocInfo.first.isInvalid())
+    return "";
+  bool Invalid = false;
+  StringRef Buffer = SM.getBufferData(LocInfo.first, &Invalid);
+  if (Invalid)
+    return "";
+  const char *Line = findBeginningOfLine(Buffer, LocInfo.second);
+  if (!Line)
+    return "";
+  StringRef Rest = Buffer.substr(Line - Buffer.data());
+  size_t NumWhitespaceChars = Rest.find_first_not_of(" \t");
+  return NumWhitespaceChars == StringRef::npos
+             ? ""
+             : Rest.take_front(NumWhitespaceChars);
+}
+
 //===----------------------------------------------------------------------===//
 // Diagnostics forwarding code.
 //===----------------------------------------------------------------------===//