[clang-format] Don't reflow across comment pragmas.

Summary:
The comment reflower wasn't taking comment pragmas as reflow stoppers. This patch fixes that.

source:
```
// long long long long
// IWYU pragma:
```
format with column limit  = 20 before:
```
// long long long
// long IWYU pragma:
```
format with column limit  = 20 after:
```
// long long long
// long
// IWYU pragma:
```

Reviewers: djasper

Reviewed By: djasper

Subscribers: cfe-commits, klimek

Differential Revision: https://reviews.llvm.org/D29450

llvm-svn: 293898

1 files changed, 34 insertions, 13 deletions

diff --git a/clang/lib/Format/BreakableToken.cpp b/clang/lib/Format/BreakableToken.cpp
index e9dd253f3ec..14557a7e370 100644
--- a/clang/lib/Format/BreakableToken.cpp
+++ b/clang/lib/Format/BreakableToken.cpp
@@ -321,13 +321,6 @@ static bool mayReflowContent(StringRef Content) {
          (!isPunctuation(Content[0]) || !isPunctuation(Content[1]));
 }
 
-bool BreakableComment::mayReflow(unsigned LineIndex) const {
-  return LineIndex > 0 && mayReflowContent(Content[LineIndex]) &&
-         !Tok.Finalized && !switchesFormatting(tokenAt(LineIndex)) &&
-         (!Tok.is(TT_LineComment) ||
-          OriginalPrefix[LineIndex] == OriginalPrefix[LineIndex - 1]);
-}
-
 BreakableBlockComment::BreakableBlockComment(
     const FormatToken &Token, unsigned StartColumn,
     unsigned OriginalStartColumn, bool FirstInLine, bool InPPDirective,
@@ -501,8 +494,9 @@ void BreakableBlockComment::insertBreak(unsigned LineIndex, unsigned TailOffset,
 BreakableToken::Split BreakableBlockComment::getSplitBefore(
     unsigned LineIndex,
     unsigned PreviousEndColumn,
-    unsigned ColumnLimit) const {
-  if (!mayReflow(LineIndex))
+    unsigned ColumnLimit,
+    llvm::Regex &CommentPragmasRegex) const {
+  if (!mayReflow(LineIndex, CommentPragmasRegex))
     return Split(StringRef::npos, 0);
   StringRef TrimmedContent = Content[LineIndex].ltrim(Blanks);
   return getReflowSplit(TrimmedContent, ReflowPrefix, PreviousEndColumn,
@@ -622,6 +616,19 @@ void BreakableBlockComment::replaceWhitespaceBefore(
       InPPDirective, /*Newlines=*/1, ContentColumn[LineIndex] - Prefix.size());
 }
 
+bool BreakableBlockComment::mayReflow(unsigned LineIndex,
+                                      llvm::Regex &CommentPragmasRegex) const {
+  // Content[LineIndex] may exclude the indent after the '*' decoration. In that
+  // case, we compute the start of the comment pragma manually.
+  StringRef IndentContent = Content[LineIndex];
+  if (Lines[LineIndex].ltrim(Blanks).startswith("*")) {
+    IndentContent = Lines[LineIndex].ltrim(Blanks).substr(1);
+  }
+  return LineIndex > 0 && !CommentPragmasRegex.match(IndentContent) &&
+         mayReflowContent(Content[LineIndex]) && !Tok.Finalized &&
+         !switchesFormatting(tokenAt(LineIndex));
+}
+
 unsigned
 BreakableBlockComment::getContentStartColumn(unsigned LineIndex,
                                              unsigned TailOffset) const {
@@ -748,10 +755,10 @@ void BreakableLineCommentSection::insertBreak(unsigned LineIndex,
 }
 
 BreakableComment::Split BreakableLineCommentSection::getSplitBefore(
-    unsigned LineIndex,
-    unsigned PreviousEndColumn,
-    unsigned ColumnLimit) const {
-  if (!mayReflow(LineIndex)) return Split(StringRef::npos, 0);
+    unsigned LineIndex, unsigned PreviousEndColumn, unsigned ColumnLimit,
+    llvm::Regex &CommentPragmasRegex) const {
+  if (!mayReflow(LineIndex, CommentPragmasRegex))
+    return Split(StringRef::npos, 0);
   return getReflowSplit(Content[LineIndex], ReflowPrefix, PreviousEndColumn,
                         ColumnLimit);
 }
@@ -850,6 +857,20 @@ void BreakableLineCommentSection::updateNextToken(LineState& State) const {
   }
 }
 
+bool BreakableLineCommentSection::mayReflow(
+    unsigned LineIndex, llvm::Regex &CommentPragmasRegex) const {
+  // Line comments have the indent as part of the prefix, so we need to
+  // recompute the start of the line.
+  StringRef IndentContent = Content[LineIndex];
+  if (Lines[LineIndex].startswith("//")) {
+    IndentContent = Lines[LineIndex].substr(2);
+  }
+  return LineIndex > 0 && !CommentPragmasRegex.match(IndentContent) &&
+         mayReflowContent(Content[LineIndex]) && !Tok.Finalized &&
+         !switchesFormatting(tokenAt(LineIndex)) &&
+         OriginalPrefix[LineIndex] == OriginalPrefix[LineIndex - 1];
+}
+
 unsigned
 BreakableLineCommentSection::getContentStartColumn(unsigned LineIndex,
                                                    unsigned TailOffset) const {