Update CHANGES and docs relative to new verbatimforcewraps

CHANGES

@@ -131,7 +131,9 @@ Bugs fixed
 * #8780: LaTeX: long words in narrow columns may not be hyphenated
 * #8788: LaTeX: ``\titleformat`` last argument in sphinx.sty should be
   bracketed, not braced (and is anyhow not needed) 
-* #8849: LaTex: code-block printed out of margin
+* #8849: LaTex: code-block printed out of margin (see the opt-in LaTeX syntax
+  boolean :ref:`verbatimforcewraps <latexsphinxsetupforcewraps>` for use via
+  the :ref:`'sphinxsetup' <latexsphinxsetup>` key of ``latex_elements``)
 
 Testing
 --------

doc/latex.rst

@@ -646,6 +646,8 @@ macros may be significant.
 
     Default: ``true``
 
+.. _latexsphinxsetupforcewraps:
+
 ``verbatimforcewraps``
     Boolean to specify if long lines in :rst:dir:`code-block`\ 's contents
     should be forcefully wrapped to never overflow due to long strings.
@@ -692,7 +694,8 @@ macros may be significant.
       }
 
     This can be done locally for a given code-block via the use of raw latex
-    directives to insert suitable ``\sphinxsetup`` into the latex file.
+    directives to insert suitable ``\sphinxsetup`` (before and after) into the
+    latex file.
 
     Default: ``100``
 

sphinx/texinputs/sphinx.sty

@@ -1224,9 +1224,10 @@
 % box does not store in an accessible way what was the maximal
 % line-width during paragraph building.
 %
-% If the max width exceed the linewidth by at least 4 character
-% widths, then we apply the "force wrapping" with potential line
-% break at each character, else we don't.
+% If the max width exceeds the linewidth by more than verbatimmaxoverfull
+% character widths, or if the min width plus verbatimmaxunderfull character
+% widths is inferior to linewidth, then we apply the "force wrapping" with
+% potential line break at each character, else we don't.
 \long\def\spx@verb@FormatLineForceWrap#1{%
     % \spx@image@box is a scratch box register that we can use here
     \global\let\spx@verb@maxwidth\z@