syntaxes: avoid coloring "this\" as if it were a valid string

A backslash should not be allowed inside a quoted string unless
it is used to escape another character.

This fixes https://savannah.gnu.org/bugs/?61389.

Bug existed since each of these syntaxes was introduced.

(Awk and Fortran do not know include files with names between
angled brackets, so those regexes are dropped in the bargain.)

syntax/asm.nanorc

@@ -12,7 +12,7 @@ color brightred "^[[:blank:]]*[.0-9A-Za-z_]*:"
 color brightcyan "^[[:blank:]]*#[[:blank:]]*(define|undef|include|ifn?def|endif|elif|else|if|warning|error)"
 
 # Strings.
-color brightyellow "<[^= 	]*>" ""(\\.|[^"])*""
+color brightyellow "<[^= 	]*>|"(\\.|[^"\])*""
 
 # Comments.
 color brightblue "//.*"

syntax/awk.nanorc

@@ -29,7 +29,7 @@ color magenta "\<(and|compl|lshift|or|rshift|xor)\>"
 color magenta "\<(bindtextdomain|dcgettext|dcngettext)\>"
 
 # Strings.
-color brightyellow "<[^= 	]*>" ""(\\.|[^"])*""
+color brightyellow ""(\\.|[^"\])*""
 # Comments.
 color brightblue "(^|[[:blank:]])#.*"
 

syntax/elisp.nanorc

@@ -28,6 +28,6 @@ color brightred "\<(t|nil)\>"
 color blue ":(\w|[?-])+"
 # Strings
 color yellow start="^[[:blank:]]+"" end="[^\]""
-color yellow ""(\\.|[^"])*""
+color yellow ""(\\.|[^"\])*""
 # Comments
 color cyan "(^|[[:blank:]]);.*"

syntax/extra/fortran.nanorc

@@ -34,7 +34,7 @@ icolor yellow "\<(.or.|repeat|select case|then|where|while)\>"
 icolor magenta "\<(continue|cycle|exit|go?to|result|return)\>"
 
 # Strings.
-color yellow "<[^= 	]*>" ""(\\.|[^"])*""
+color yellow ""(\\.|[^"\])*""
 
 # Comments.
 color blue "!.*"

syntax/extra/gentoo.nanorc

@@ -41,7 +41,7 @@ color blue "\<(awk|cat|cd|chmod|chown|cp|echo|env|find|e?grep|ln|make|mkdir|mv|p
 ## Comments (doesn't work that well):
 color yellow "(^|[[:space:]])#.*"
 ## Strings (doesn't work that well):
-color brightyellow ""(\\.|[^\"])*"|'(\\.|[^'])*'"
+color brightyellow ""(\\.|[^"\])*"|'(\\.|[^'\])*'"
 ## Trailing space is bad!
 color ,green "[[:space:]]+$"
 ## Mixed whitespace is also bad.

syntax/extra/haskell.nanorc

@@ -28,9 +28,9 @@ color magenta "\<(Bounded|Data|Enum|Eq|Floating|Fractional|Functor|Integral|Mona
 color brightred "undefined"
 
 # Strings
-color yellow ""([^\"]|\\.)*""
+color yellow ""([^"\]|\\.)*""
 # Characters
-color brightyellow "'([^\']|\\.)'"
+color brightyellow "'([^'\]|\\.)'"
 
 # Comments
 color green "--.*"

syntax/go.nanorc

@@ -34,8 +34,8 @@ color red "\<[0-9]+i\>"
 
 # Strings and characters; slightly fuzzy.
 color red "\<(true|false|nil|iota|_)\>"
-color red ""(\\.|[^"])*"|'(\\.|[^'])+'"
-color red start=""(\\.|[^"])*\\[[:blank:]]*$" end="^(\\.|[^"])*""
+color red ""(\\.|[^"\])*"|'(\\.|[^'\])+'"
+color red start=""(\\.|[^"\])*\\[[:blank:]]*$" end="^(\\.|[^"\])*""
 
 # Comments.
 color brightblue "//.*"

syntax/guile.nanorc

@@ -19,6 +19,6 @@ color brightred "(#t|#f)\>"
 color blue "#?:(\w|[?-])+"
 # Strings
 color yellow start="^[[:blank:]]+"" end="[^\]""
-color yellow ""(\\.|[^"])*""
+color yellow ""(\\.|[^"\])*""
 # Comments
 color cyan "(^|[[:blank:]]);.*"

syntax/html.nanorc

@@ -25,7 +25,7 @@ color red "\<(rows(pan)?|rules|scheme|scope|scrolling|selected|shape|size|span|s
 color red "\<(tabindex|target|text|title|type|usemap|valign|value(type)?|vlink|vspace|width|xmlns|xml:space)="
 
 # Strings:
-color green ""(\\.|[^"])*""
+color green ""(\\.|[^"\])*""
 
 # Comments:
 color yellow start="<!--" end="-->"

syntax/javascript.nanorc

@@ -17,7 +17,7 @@ color cyan "\<([0-9]+|0x[0-9A-Fa-f]+)\>"
 color cyan "\<(true|false|null|undefined)\>"
 
 # Strings.
-color brightmagenta ""(\\.|[^"])*"|'(\\.|[^'])*'|`(\\.|[^`])*`"
+color brightmagenta ""(\\.|[^"\])*"|'(\\.|[^'\])*'|`(\\.|[^`\])*`"
 # Comments.
 color brightblue "(^|[[:blank:]])//.*"
 color brightblue start="/\*" end="\*/"

syntax/nftables.nanorc

@@ -26,7 +26,7 @@ color cyan "(^|[[:blank:]])#.*"
 color ,green "[[:space:]]+$"
 
 # Strings and others
-color yellow ""(\\.|[^"])*"|'(\\.|[^'])*'"
+color yellow ""(\\.|[^"\])*"|'(\\.|[^'\])*'"
 color green "[][{}():;|`$<>!=&\]"
 
 # Basic variable names

syntax/objc.nanorc

@@ -25,8 +25,8 @@ color white "\[[^][:blank:]]*\]"
 
 # Strings.
 color brightblack "'([^'\]|(\\["'abfnrtv\]))'" "'\\(([0-3]?[0-7]{1,2}))'" "'\\x[0-9A-Fa-f]{1,2}'"
-color brightblack "<[^= 	]*>" ""(\\.|[^"])*""
-color brightblue "@"(\\.|[^"])*""
+color brightblack "<[^= 	]*>|"(\\.|[^"\])*""
+color brightblue "@"(\\.|[^"\])*""
 
 # Preprocessor commands.
 color brightblue "^[[:blank:]]*#[[:blank:]]*(define|include|import|(un|ifn?)def|endif|el(if|se)|if|warning|error)"

syntax/php.nanorc

@@ -25,7 +25,7 @@ color brightcyan "\<(and|or|xor)\>"
 color magenta "\<(break|continue|goto|return)\>"
 
 # Strings.
-color brightyellow ""(\\.|[^"])*"|'(\\.|[^'])*'"
+color brightyellow ""(\\.|[^"\])*"|'(\\.|[^'\])*'"
 
 # Comments.
 color brightblue "(^|[[:blank:]]+)//.*"

syntax/sh.nanorc

@@ -33,7 +33,7 @@ color brightred "\$\{[#!]?([-@*#?$!]|[0-9]+|[[:alpha:]_][[:alnum:]_]*)(\[([[:bla
 color cyan "(^|[[:blank:]])#.*"
 
 # Strings.
-color brightyellow ""(\\.|[^"])*"|'(\\.|[^'])*'"
+color brightyellow ""(\\.|[^"\])*"|'(\\.|[^'\])*'"
 
 # Trailing whitespace.
 color ,green "[[:space:]]+$"

syntax/tcl.nanorc

@@ -17,7 +17,7 @@ color green "\<(alarm|auto_load_pkg|bsearch|catclose|catgets|catopen|ccollate|cc
 # Syntax:
 color brightblue "\<proc[[:blank:]]|\{|\}"
 color green "\(|\)|\;|`|\\|\$|<|>|!|=|&|\|"
-color brightyellow ""(\\.|[^"])*"|'(\\.|[^'])*'"
+color brightyellow ""(\\.|[^"\])*"|'(\\.|[^'\])*'"
 color brightred "\$\{?[0-9A-Za-z_!@#$*?-]+\}?"
 
 # Trailing whitespace: