Re-apply r160319 "Don't crash when emitting fixits following Unicode chars"

This time, make sure we don't try to print fixits with newline characters,
since they don't have a valid column width, and they don't look good anyway.

PR13417 (and originally <rdar://problem/11877454>)

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@160561 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 29 insertions, 29 deletions

diff --git a/lib/Frontend/TextDiagnostic.cpp b/lib/Frontend/TextDiagnostic.cpp
index 306306d3ac..1f2e2c05c5 100644
--- a/lib/Frontend/TextDiagnostic.cpp
+++ b/lib/Frontend/TextDiagnostic.cpp
@@ -1124,23 +1124,28 @@ std::string TextDiagnostic::buildFixItInsertionLine(
   std::string FixItInsertionLine;
   if (Hints.empty() || !DiagOpts.ShowFixits)
     return FixItInsertionLine;
-  unsigned PrevHintEnd = 0;
+  unsigned PrevHintEndCol = 0;
 
   for (ArrayRef<FixItHint>::iterator I = Hints.begin(), E = Hints.end();
        I != E; ++I) {
     if (!I->CodeToInsert.empty()) {
       // We have an insertion hint. Determine whether the inserted
-      // code is on the same line as the caret.
+      // code contains no newlines and is on the same line as the caret.
       std::pair<FileID, unsigned> HintLocInfo
         = SM.getDecomposedExpansionLoc(I->RemoveRange.getBegin());
-      if (LineNo == SM.getLineNumber(HintLocInfo.first, HintLocInfo.second)) {
+      if (LineNo == SM.getLineNumber(HintLocInfo.first, HintLocInfo.second) &&
+          StringRef(I->CodeToInsert).find_first_of("\n\r") == StringRef::npos) {
         // Insert the new code into the line just below the code
         // that the user wrote.
-        unsigned HintColNo
+        // Note: When modifying this function, be very careful about what is a
+        // "column" (printed width, platform-dependent) and what is a
+        // "byte offset" (SourceManager "column").
+        unsigned HintByteOffset
           = SM.getColumnNumber(HintLocInfo.first, HintLocInfo.second) - 1;
-        // hint must start inside the source or right at the end
-        assert(HintColNo<static_cast<unsigned>(map.bytes())+1);
-        HintColNo = map.byteToColumn(HintColNo);
+
+        // The hint must start inside the source or right at the end
+        assert(HintByteOffset < static_cast<unsigned>(map.bytes())+1);
+        unsigned HintCol = map.byteToColumn(HintByteOffset);
 
         // If we inserted a long previous hint, push this one forwards, and add
         // an extra space to show that this is not part of the previous
@@ -1149,32 +1154,27 @@ std::string TextDiagnostic::buildFixItInsertionLine(
         //
         // Note that if this hint is located immediately after the previous
         // hint, no space will be added, since the location is more important.
-        if (HintColNo < PrevHintEnd)
-          HintColNo = PrevHintEnd + 1;
-
-        // FIXME: if the fixit includes tabs or other characters that do not
-        //  take up a single column per byte when displayed then
-        //  I->CodeToInsert.size() is not a column number and we're mixing
-        //  units (columns + bytes). We should get printable versions
-        //  of each fixit before using them.
-        unsigned LastColumnModified
-          = HintColNo + I->CodeToInsert.size();
-
-        if (LastColumnModified <= static_cast<unsigned>(map.bytes())) {
-          // If we're right in the middle of a multibyte character skip to
-          // the end of it.
-          while (map.byteToColumn(LastColumnModified) == -1)
-            ++LastColumnModified;
-          LastColumnModified = map.byteToColumn(LastColumnModified);
-        }
-
+        if (HintCol < PrevHintEndCol)
+          HintCol = PrevHintEndCol + 1;
+
+        // FIXME: This function handles multibyte characters in the source, but
+        // not in the fixits. This assertion is intended to catch unintended
+        // use of multibyte characters in fixits. If we decide to do this, we'll
+        // have to track separate byte widths for the source and fixit lines.
+        assert((size_t)llvm::sys::locale::columnWidth(I->CodeToInsert) ==
+               I->CodeToInsert.size());
+
+        // This relies on one byte per column in our fixit hints.
+        // This should NOT use HintByteOffset, because the source might have
+        // Unicode characters in earlier columns.
+        unsigned LastColumnModified = HintCol + I->CodeToInsert.size();
         if (LastColumnModified > FixItInsertionLine.size())
           FixItInsertionLine.resize(LastColumnModified, ' ');
-        assert(HintColNo+I->CodeToInsert.size() <= FixItInsertionLine.size());
+
         std::copy(I->CodeToInsert.begin(), I->CodeToInsert.end(),
-                  FixItInsertionLine.begin() + HintColNo);
+                  FixItInsertionLine.begin() + HintCol);
 
-        PrevHintEnd = LastColumnModified;
+        PrevHintEndCol = LastColumnModified;
       } else {
         FixItInsertionLine.clear();
         break;