[LyX/master] On export, mark the start of the first paragraph

[Enrico Forestieri]

commit 9ba76e6c40738f9bd0d45d4cdb00a9842d47feec
Author: Enrico Forestieri <for...@lyx.org>
Date:   Sun Oct 23 18:04:13 2016 +0200

    On export, mark the start of the first paragraph
    
    No newline is written after \begin{document}, such that
    the afterParbreak method would return false. This misleads
    the code that outputs a display math in an ulem command
    to emit a newline command instead of \noindent, causing
    latex errors. This occurs only if the math is at the very
    start of a document, without anything before it.
---
 src/Buffer.cpp |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/src/Buffer.cpp b/src/Buffer.cpp
index 67d4b3d..df3ae9f 100644
--- a/src/Buffer.cpp
+++ b/src/Buffer.cpp
@@ -1891,6 +1891,10 @@ void Buffer::writeLaTeXSource(otexstream & os,
                os.texrow().start(TexRow::beginDocument());
                os << "\\begin{document}\n";
 
+               // mark the start of a new paragraph by simulating a newline,
+               // so that os.afterParbreak() returns true at document start
+               os.lastChar('\n');
+
                // output the parent macros
                MacroSet::iterator it = parentMacros.begin();
                MacroSet::iterator end = parentMacros.end();