Merge pull request sphinx-doc#8926 from jfbu/latex_maxunderfull

LaTeX: let underfull calculation in wrapped code lines ignore last line

CHANGES

@@ -75,6 +75,8 @@ Bugs fixed
   change) with late TeXLive 2019
 * #8253: LaTeX: Figures with no size defined get overscaled (compared to images
   with size explicitly set in pixels) (fixed for ``'pdflatex'/'lualatex'`` only)
+* #8925: LaTeX: 3.5.0 ``verbatimmaxunderfull`` setting does not work as
+  expected
 * #8911: C++: remove the longest matching prefix in
   :confval:`cpp_index_common_prefix` instead of the first that matches.
 * C, properly reject function declarations when a keyword is used

sphinx/texinputs/sphinxlatexliterals.sty

@@ -343,8 +343,21 @@
     \fi\fi
 }%
 % auxiliary paragraph dissector to get max and min widths
+% but minwidth must not take into account the last line
 \newbox\spx@scratchbox
 \def\spx@verb@getwidths {%
+    \unskip\unpenalty
+    \setbox\spx@scratchbox\lastbox
+    \ifvoid\spx@scratchbox
+    \else
+       \setbox\spx@scratchbox\hbox{\unhbox\spx@scratchbox}%
+       \ifdim\spx@verb@maxwidth<\wd\spx@scratchbox
+          \xdef\spx@verb@maxwidth{\number\wd\spx@scratchbox sp}%
+       \fi
+       \expandafter\spx@verb@getwidths@loop
+    \fi
+}%
+\def\spx@verb@getwidths@loop {%
     \unskip\unpenalty
     \setbox\spx@scratchbox\lastbox
     \ifvoid\spx@scratchbox
@@ -356,7 +369,7 @@
        \ifdim\spx@verb@minwidth>\wd\spx@scratchbox
           \xdef\spx@verb@minwidth{\number\wd\spx@scratchbox sp}%
        \fi
-       \expandafter\spx@verb@getwidths
+       \expandafter\spx@verb@getwidths@loop
     \fi
 }%
 % auxiliary macros to implement "cut long line even in middle of word"