1 files changed, 33 insertions, 22 deletions

diff --git a/lib/Format/FormatToken.cpp b/lib/Format/FormatToken.cpp
index badb3a3..88678ca 100644
--- a/lib/Format/FormatToken.cpp
+++ b/lib/Format/FormatToken.cpp
@@ -18,6 +18,7 @@
 #include "clang/Format/Format.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/Debug.h"
+#include <climits>
 
 namespace clang {
 namespace format {
@@ -59,12 +60,13 @@ void TokenRole::precomputeFormattingInfos(const FormatToken *Token) {}
 unsigned CommaSeparatedList::formatAfterToken(LineState &State,
                                               ContinuationIndenter *Indenter,
                                               bool DryRun) {
-  if (!State.NextToken->Previous || !State.NextToken->Previous->Previous)
+  if (State.NextToken == nullptr || !State.NextToken->Previous)
     return 0;
 
   // Ensure that we start on the opening brace.
-  const FormatToken *LBrace = State.NextToken->Previous->Previous;
-  if (LBrace->isNot(tok::l_brace) || LBrace->BlockKind == BK_Block ||
+  const FormatToken *LBrace =
+      State.NextToken->Previous->getPreviousNonComment();
+  if (!LBrace || LBrace->isNot(tok::l_brace) || LBrace->BlockKind == BK_Block ||
       LBrace->Type == TT_DictLiteral ||
       LBrace->Next->Type == TT_DesignatedInitializerPeriod)
     return 0;
@@ -132,9 +134,9 @@ void CommaSeparatedList::precomputeFormattingInfos(const FormatToken *Token) {
     return;
 
   // In C++11 braced list style, we should not format in columns unless they
-  // have many items (20 or more) or we allow bin-packing of function
-  // parameters.
-  if (Style.Cpp11BracedListStyle && !Style.BinPackParameters &&
+  // have many items (20 or more) or we allow bin-packing of function call
+  // arguments.
+  if (Style.Cpp11BracedListStyle && !Style.BinPackArguments &&
       Commas.size() < 19)
     return;
 
@@ -143,19 +145,21 @@ void CommaSeparatedList::precomputeFormattingInfos(const FormatToken *Token) {
     return;
 
   FormatToken *ItemBegin = Token->Next;
+  while (ItemBegin->isTrailingComment())
+    ItemBegin = ItemBegin->Next;
   SmallVector<bool, 8> MustBreakBeforeItem;
 
   // The lengths of an item if it is put at the end of the line. This includes
   // trailing comments which are otherwise ignored for column alignment.
   SmallVector<unsigned, 8> EndOfLineItemLength;
 
-  unsigned MinItemLength = Style.ColumnLimit;
-  unsigned MaxItemLength = 0;
-
+  bool HasSeparatingComment = false;
   for (unsigned i = 0, e = Commas.size() + 1; i != e; ++i) {
     // Skip comments on their own line.
-    while (ItemBegin->HasUnescapedNewline && ItemBegin->isTrailingComment())
+    while (ItemBegin->HasUnescapedNewline && ItemBegin->isTrailingComment()) {
       ItemBegin = ItemBegin->Next;
+      HasSeparatingComment = i > 0;
+    }
 
     MustBreakBeforeItem.push_back(ItemBegin->MustBreakBefore);
     if (ItemBegin->is(tok::l_brace))
@@ -178,8 +182,6 @@ void CommaSeparatedList::precomputeFormattingInfos(const FormatToken *Token) {
       ItemEnd = Commas[i];
       // The comma is counted as part of the item when calculating the length.
       ItemLengths.push_back(CodePointsBetween(ItemBegin, ItemEnd));
-      MinItemLength = std::min(MinItemLength, ItemLengths.back());
-      MaxItemLength = std::max(MaxItemLength, ItemLengths.back());
 
       // Consume trailing comments so the are included in EndOfLineItemLength.
       if (ItemEnd->Next && !ItemEnd->Next->HasUnescapedNewline &&
@@ -194,12 +196,9 @@ void CommaSeparatedList::precomputeFormattingInfos(const FormatToken *Token) {
     ItemBegin = ItemEnd->Next;
   }
 
-  // If this doesn't have a nested list, we require at least 6 elements in order
-  // create a column layout. If it has a nested list, column layout ensures one
-  // list element per line. If the difference between the shortest and longest
-  // element is too large, column layout would create too much whitespace.
-  if (HasNestedBracedList || Commas.size() < 5 || Token->NestingLevel != 0 ||
-      MaxItemLength - MinItemLength > 10)
+  // Don't use column layout for nested lists, lists with few elements and in
+  // presence of separating comments.
+  if (Token->NestingLevel != 0 || Commas.size() < 5 || HasSeparatingComment)
     return;
 
   // We can never place more than ColumnLimit / 3 items in a row (because of the
@@ -208,6 +207,7 @@ void CommaSeparatedList::precomputeFormattingInfos(const FormatToken *Token) {
     ColumnFormat Format;
     Format.Columns = Columns;
     Format.ColumnSizes.resize(Columns);
+    std::vector<unsigned> MinSizeInColumn(Columns, UINT_MAX);
     Format.LineCount = 1;
     bool HasRowWithSufficientColumns = false;
     unsigned Column = 0;
@@ -219,9 +219,10 @@ void CommaSeparatedList::precomputeFormattingInfos(const FormatToken *Token) {
       }
       if (Column == Columns - 1)
         HasRowWithSufficientColumns = true;
-      unsigned length =
+      unsigned Length =
           (Column == Columns - 1) ? EndOfLineItemLength[i] : ItemLengths[i];
-      Format.ColumnSizes[Column] = std::max(Format.ColumnSizes[Column], length);
+      Format.ColumnSizes[Column] = std::max(Format.ColumnSizes[Column], Length);
+      MinSizeInColumn[Column] = std::min(MinSizeInColumn[Column], Length);
       ++Column;
     }
     // If all rows are terminated early (e.g. by trailing comments), we don't
@@ -229,9 +230,19 @@ void CommaSeparatedList::precomputeFormattingInfos(const FormatToken *Token) {
     if (!HasRowWithSufficientColumns)
       break;
     Format.TotalWidth = Columns - 1; // Width of the N-1 spaces.
-    for (unsigned i = 0; i < Columns; ++i) {
+
+    for (unsigned i = 0; i < Columns; ++i)
       Format.TotalWidth += Format.ColumnSizes[i];
-    }
+
+    // Don't use this Format, if the difference between the longest and shortest
+    // element in a column exceeds a threshold to avoid excessive spaces.
+    if ([&] {
+          for (unsigned i = 0; i < Columns - 1; ++i)
+            if (Format.ColumnSizes[i] - MinSizeInColumn[i] > 10)
+              return true;
+          return false;
+        }())
+      continue;
 
     // Ignore layouts that are bound to violate the column limit.
     if (Format.TotalWidth > Style.ColumnLimit)