Avoid multi-line emph in LaTeX backend

`markupWarning` often processes inputs which span across paragraphs.
Unfortunately, LaTeX's `emph` is not made to handle this (and will
crash).

Fixes #936.

Author: harpocrates

haddock-api/src/Haddock/Backends/LaTeX.hs

@@ -1191,7 +1191,7 @@ parLatexMarkup ppId = Markup {
   markupIdentifier           = markupId ppId,
   markupIdentifierUnchecked  = markupId (ppVerbOccName . fmap snd),
   markupModule               = \m _ -> let (mdl,_ref) = break (=='#') m in tt (text mdl),
-  markupWarning              = \p v -> emph (p v),
+  markupWarning              = \p v -> p v,
   markupEmphasis             = \p v -> emph (p v),
   markupBold                 = \p v -> bold (p v),
   markupMonospaced           = \p _ -> tt (p Mono),

latex-test/ref/Deprecated/Deprecated.tex

@@ -0,0 +1,17 @@
+\haddockmoduleheading{Deprecated}
+\label{module:Deprecated}
+\haddockbeginheader
+{\haddockverb\begin{verbatim}
+module Deprecated (
+    deprecated
+  ) where\end{verbatim}}
+\haddockendheader
+
+\begin{haddockdesc}
+\item[\begin{tabular}{@{}l}
+deprecated\ ::\ Int
+\end{tabular}]\haddockbegindoc
+Deprecated: Don't use this\par
+Docs for something deprecated\par
+
+\end{haddockdesc}

latex-test/ref/Deprecated/haddock.sty

@@ -0,0 +1,57 @@
+% Default Haddock style definitions.  To use your own style, invoke
+% Haddock with the option --latex-style=mystyle.
+
+\usepackage{tabulary} % see below
+
+% make hyperlinks in the PDF, and add an expandabale index
+\usepackage[pdftex,bookmarks=true]{hyperref}
+
+\newenvironment{haddocktitle}
+  {\begin{center}\bgroup\large\bfseries}
+  {\egroup\end{center}}
+\newenvironment{haddockprologue}{\vspace{1in}}{}
+
+\newcommand{\haddockmoduleheading}[1]{\chapter{\texttt{#1}}}
+
+\newcommand{\haddockbeginheader}{\hrulefill}
+\newcommand{\haddockendheader}{\noindent\hrulefill}
+
+% a little gap before the ``Methods'' header
+\newcommand{\haddockpremethods}{\vspace{2ex}}
+
+% inserted before \\begin{verbatim}
+\newcommand{\haddockverb}{\small}
+
+% an identifier: add an index entry
+\newcommand{\haddockid}[1]{\haddocktt{#1}\index{#1@\texttt{#1}}}
+
+% The tabulary environment lets us have a column that takes up ``the
+% rest of the space''.  Unfortunately it doesn't allow
+% the \end{tabulary} to be in the expansion of a macro, it must appear
+% literally in the document text, so Haddock inserts
+% the \end{tabulary} itself.
+\newcommand{\haddockbeginconstrs}{\begin{tabulary}{\linewidth}{@{}llJ@{}}}
+\newcommand{\haddockbeginargs}{\begin{tabulary}{\linewidth}{@{}llJ@{}}}
+
+\newcommand{\haddocktt}[1]{{\small \texttt{#1}}}
+\newcommand{\haddockdecltt}[1]{{\small\bfseries \texttt{#1}}}
+
+\makeatletter
+\newenvironment{haddockdesc}
+               {\list{}{\labelwidth\z@ \itemindent-\leftmargin
+                        \let\makelabel\haddocklabel}}
+               {\endlist}
+\newcommand*\haddocklabel[1]{\hspace\labelsep\haddockdecltt{#1}}
+\makeatother
+
+% after a declaration, start a new line for the documentation.
+% Otherwise, the documentation starts right after the declaration,
+% because we're using the list environment and the declaration is the
+% ``label''.  I tried making this newline part of the label, but
+% couldn't get that to work reliably (the space seemed to stretch
+% sometimes).
+\newcommand{\haddockbegindoc}{\hfill\\[1ex]}
+
+% spacing between paragraphs and no \parindent looks better
+\parskip=10pt plus2pt minus2pt
+\setlength{\parindent}{0cm}

latex-test/ref/Deprecated/main.tex

@@ -0,0 +1,11 @@
+\documentclass{book}
+\usepackage{haddock}
+\begin{document}
+\begin{titlepage}
+\begin{haddocktitle}
+
+\end{haddocktitle}
+\end{titlepage}
+\tableofcontents
+\input{Deprecated}
+\end{document}

latex-test/src/Deprecated/Deprecated.hs

@@ -0,0 +1,7 @@
+module Deprecated where
+
+-- | Docs for something deprecated
+deprecated :: Int
+deprecated = 1
+
+{-# DEPRECATED deprecated "Don't use this" #-}