T.P.RoffChar: escape - as \-.

The groff_man (7)` man page indicates that `-` characters will be
treated as typographic hyphens and are not appropriate for cases
where the output should be copy-pasteable as an ASCII
hyphen-minus character.  (E.g. in command line options.)

However, until a recent update groff man did not actually do this;
it treated `-` and `\-` the same.  With the new update (1.23.0)
the two are distinguished (see https://lwn.net/Articles/947941/
for background), so now it is important that pandoc escape `-`.

This reverts ee60ba5.
That change was motivated by a problem with backslash-escaping
`-` in a filename for .PSPIC. That's simply a separate issue;
we shouldn't do the normal escapes in such a context. It has
been addressed in the previous commit.

src/Text/Pandoc/RoffChar.hs

@@ -34,6 +34,7 @@ standardEscapes =
   , ('`', "\\[ga]")
   , ('^', "\\[ha]")
   , ('~', "\\[ti]")
+  , ('-', "\\-")
   , ('\\', "\\[rs]")
   , ('@', "\\[at]") -- because we use @ as a table and math delimiter
   , ('\x2026', "\\&...")  -- because u2026 doesn't render on tty

test/command/5620.md

@@ -4,6 +4,6 @@
 :   Write output to *OUTFILE* instead of `stdout`(3)
 ^D
 .TP
-\f[CR]-o\f[R], \f[CR]--output=\f[R]\f[I]OUTFILE\f[R]
+\f[CR]\-o\f[R], \f[CR]\-\-output=\f[R]\f[I]OUTFILE\f[R]
 Write output to \f[I]OUTFILE\f[R] instead of \f[CR]stdout\f[R](3)
 ```

test/writer.man

@@ -23,7 +23,7 @@ Here\[cq]s a regular paragraph.
 In Markdown 1.0.0 and earlier.
 Version 8.
 This line turns into a list item.
-Because a hard-wrapped line in the middle of a paragraph looked like a list
+Because a hard\-wrapped line in the middle of a paragraph looked like a list
 item.
 .PP
 Here\[cq]s one with a bullet.
@@ -37,7 +37,7 @@ here.
 .PP
    *   *   *   *   *
 .SH Block Quotes
-E-mail style:
+E\-mail style:
 .RS
 .PP
 This is a block quote.
@@ -79,7 +79,7 @@ And a following paragraph.
 Code:
 .IP
 .EX
----- (should be four hyphens)
+\-\-\-\- (should be four hyphens)
 
 sub status {
     print \[dq]working\[dq];
@@ -430,7 +430,7 @@ Multiline:
 Code block:
 .IP
 .EX
-<!-- Comment -->
+<!\-\- Comment \-\->
 .EE
 .PP
 Just plain comment, with trailing spaces on the line:
@@ -507,11 +507,11 @@ Ellipses\&...and\&...and\&....
 .IP \[bu] 2
 223
 .IP \[bu] 2
-\f[I]p\f[R]-Tree
+\f[I]p\f[R]\-Tree
 .IP \[bu] 2
 Here\[cq]s some display math:
 .RS
-$$\[rs]frac{d}{dx}f(x)=\[rs]lim_{h\[rs]to 0}\[rs]frac{f(x+h)-f(x)}{h}$$
+$$\[rs]frac{d}{dx}f(x)=\[rs]lim_{h\[rs]to 0}\[rs]frac{f(x+h)\-f(x)}{h}$$
 .RE
 .IP \[bu] 2
 Here\[cq]s one that has a line break in it:
@@ -575,7 +575,7 @@ Left paren: (
 .PP
 Right paren: )
 .PP
-Greater-than: >
+Greater\-than: >
 .PP
 Hash: #
 .PP
@@ -585,7 +585,7 @@ Bang: !
 .PP
 Plus: +
 .PP
-Minus: -
+Minus: \-
 .PP
    *   *   *   *   *
 .SH Links
@@ -661,7 +661,7 @@ In a list?
 .IP \[bu] 2
 It should.
 .PP
-An e-mail address: \c
+An e\-mail address: \c
 .MT [email protected]
 .ME \c
 .RS
@@ -671,7 +671,7 @@ Blockquoted: \c
 .UE \c
 .RE
 .PP
-Auto-links should not occur here: \f[CR]<http://example.com/>\f[R]
+Auto\-links should not occur here: \f[CR]<http://example.com/>\f[R]
 .IP
 .EX
 or here: <http://example.com/>

test/writer.ms

@@ -134,7 +134,7 @@ Here\[cq]s a regular paragraph.
 In Markdown 1.0.0 and earlier.
 Version 8.
 This line turns into a list item.
-Because a hard-wrapped line in the middle of a paragraph looked like a list
+Because a hard\-wrapped line in the middle of a paragraph looked like a list
 item.
 .PP
 Here\[cq]s one with a bullet.
@@ -149,7 +149,7 @@ Block Quotes
 .pdfhref O 1 "Block Quotes"
 .pdfhref M "block-quotes"
 .LP
-E-mail style:
+E\-mail style:
 .QS
 .LP
 This is a block quote.
@@ -197,7 +197,7 @@ Code:
 .IP
 .nf
 \f[C]
----- (should be four hyphens)
+\-\-\-\- (should be four hyphens)
 
 sub status {
     print \[dq]working\[dq];
@@ -605,7 +605,7 @@ Code block:
 .IP
 .nf
 \f[C]
-<!-- Comment -->
+<!\-\- Comment \-\->
 \f[]
 .fi
 .LP
@@ -695,7 +695,7 @@ LaTeX
 .IP \[bu] 3
 @223@
 .IP \[bu] 3
-@p@-Tree
+@p@\-Tree
 .IP \[bu] 3
 Here\[cq]s some display math:
 .EQ
@@ -765,7 +765,7 @@ Left paren: (
 .PP
 Right paren: )
 .PP
-Greater-than: >
+Greater\-than: >
 .PP
 Hash: #
 .PP
@@ -775,7 +775,7 @@ Bang: !
 .PP
 Plus: +
 .PP
-Minus: -
+Minus: \-
 .HLINE
 .SH 1
 Links
@@ -925,7 +925,7 @@ In a list?
 .IP \[bu] 3
 It should.
 .LP
-An e-mail address: \c
+An e\-mail address: \c
 .pdfhref W -D "mailto:nobody%40nowhere.net" -A "\c" \
  -- "nobody\[at]nowhere.net"
 \&
@@ -937,7 +937,7 @@ Blockquoted: \c
 \&
 .QE
 .LP
-Auto-links should not occur here: \f[CR]<http://example.com/>\f[R]
+Auto\-links should not occur here: \f[CR]<http://example.com/>\f[R]
 .IP
 .nf
 \f[C]