From: Jean-Marc Lasgouttes <lasgouttes@lyx.org>
Date: Wed, 3 Jan 2018 17:28:55 +0000 (+0100)
Subject: Remove 'premature optimization' that proved buggy
X-Git-Tag: 2.3.0rc2~66
X-Git-Url: https://git.lyx.org/gitweb/?a=commitdiff_plain;h=894ae19224d0537c0c9ebd9ad45e547279769bd8;p=features.git

Remove 'premature optimization' that proved buggy

At some time it seemed like a good idea in breakRow() to return early
when the row was bound to be empty. It turns out that this creates two
symptoms:

* empty paragraphs will not have an end of paragraph marker

* since row width is not correctly computed in this case, caret ghosts
  can appear in master.

This commit removes the oprimization and replace the do {} while()
construct to a straightforward while() {}.

Related to bug #10952.

(cherry picked from commit 76f0a3dd4ee5c7958c6dea79628ef8c2ac2c59bd)
---

diff --git a/src/TextMetrics.cpp b/src/TextMetrics.cpp
index 6c5a322277..620514421b 100644
--- a/src/TextMetrics.cpp
+++ b/src/TextMetrics.cpp
@@ -834,11 +834,6 @@ bool TextMetrics::breakRow(Row & row, int const right_margin) const
 	// the width available for the row.
 	int const width = max_width_ - row.right_margin;
 
-	if (pos >= end || row.width() > width) {
-		row.endpos(end);
-		return need_new_row;
-	}
-
 #if 0
 	//FIXME: As long as leftMargin() is not correctly implemented for
 	// MARGIN_RIGHT_ADDRESS_BOX, we should also not do this here.
@@ -857,10 +852,7 @@ bool TextMetrics::breakRow(Row & row, int const right_margin) const
 	// or the end of the par, then build a representation of the row.
 	pos_type i = pos;
 	FontIterator fi = FontIterator(*this, par, row.pit(), pos);
-	do {
-		// this can happen for an empty row after a newline
-		if (i >= end)
-			break;
+	while (i < end && row.width() <= width) {
 		char_type c = par.getChar(i);
 		// The most special cases are handled first.
 		if (par.isInset(i)) {
@@ -942,7 +934,7 @@ bool TextMetrics::breakRow(Row & row, int const right_margin) const
 
 		++i;
 		++fi;
-	} while (i < end && row.width() <= width);
+	}
 	row.finalizeLast();
 	row.endpos(i);