Remove unnecessary escaping for # and ~ inside key name tokens

While at it, don't escape "?", I don't know why 68e167d576 (f-k-r should
use the user's locale, 2016-06-29) did that. Question mark is only special
in combination with redirections.

src/builtins/bind.rs

@@ -127,17 +127,20 @@ fn list_one(
                 }
             }
             KeyNameStyle::RawEscapeSequence => {
-                for key in seq {
+                for (i, key) in seq.iter().enumerate() {
                     if key.modifiers == Modifiers::ALT {
-                        out.push_utfstr(&char_to_symbol('\x1b'));
-                        out.push_utfstr(&char_to_symbol(if key.codepoint == key::Escape {
-                            '\x1b'
-                        } else {
-                            key.codepoint
-                        }));
+                        out.push_utfstr(&char_to_symbol('\x1b', i == 0));
+                        out.push_utfstr(&char_to_symbol(
+                            if key.codepoint == key::Escape {
+                                '\x1b'
+                            } else {
+                                key.codepoint
+                            },
+                            false,
+                        ));
                     } else {
                         assert!(key.modifiers.is_none());
-                        out.push_utfstr(&char_to_symbol(key.codepoint));
+                        out.push_utfstr(&char_to_symbol(key.codepoint, i == 0));
                     }
                 }
             }

src/builtins/fish_key_reader.rs

@@ -92,8 +92,8 @@ fn process_input(streams: &mut IoStreams, continuous_mode: bool, verbose: bool)
         };
         if verbose {
             streams.out.append(L!("# decoded from: "));
-            for byte in kevt.seq.chars() {
-                streams.out.append(char_to_symbol(byte));
+            for (i, byte) in kevt.seq.chars().enumerate() {
+                streams.out.append(char_to_symbol(byte, i == 0));
             }
             streams.out.append(L!("\n"));
         }

src/input_common.rs

@@ -377,7 +377,7 @@ fn readb(in_fd: RawFd, blocking: bool) -> ReadbResult {
                 return ReadbResult::Eof;
             }
             let c = arr[0];
-            FLOG!(reader, "Read byte", char_to_symbol(char::from(c)));
+            FLOG!(reader, "Read byte", char_to_symbol(char::from(c), true));
             // The common path is to return a u8.
             return ReadbResult::Byte(c);
         }
@@ -1646,7 +1646,7 @@ fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
             if i != 0 {
                 write!(f, " ")?;
             }
-            write!(f, "{}", char_to_symbol(char::from(c)))?;
+            write!(f, "{}", char_to_symbol(char::from(c), i == 0))?;
         }
         Ok(())
     }

src/key.rs

@@ -416,7 +416,8 @@ fn from(key: Key) -> Self {
                         )
                     })
             });
-        let mut res = name.unwrap_or_else(|| char_to_symbol(key.codepoint));
+        let mut res =
+            name.unwrap_or_else(|| char_to_symbol(key.codepoint, key.modifiers.is_none()));
 
         if key.modifiers.shift {
             res.insert_utfstr(0, L!("shift-"));
@@ -453,12 +454,12 @@ fn ctrl_to_symbol(buf: &mut WString, c: char) {
 
 /// Return true if the character must be escaped when used in the sequence of chars to be bound in
 /// a `bind` command.
-fn must_escape(c: char) -> bool {
-    "~[]()<>{}*\\?$#;&|'\"".contains(c)
+fn must_escape(is_first_in_token: bool, c: char) -> bool {
+    "[]()<>{}*\\$;&|'\"".contains(c) || (is_first_in_token && "~#".contains(c))
 }
 
-fn ascii_printable_to_symbol(buf: &mut WString, c: char) {
-    if must_escape(c) {
+fn ascii_printable_to_symbol(buf: &mut WString, is_first_in_token: bool, c: char) {
+    if must_escape(is_first_in_token, c) {
         sprintf!(=> buf, "\\%c", c);
     } else {
         sprintf!(=> buf, "%c", c);
@@ -466,14 +467,14 @@ fn ascii_printable_to_symbol(buf: &mut WString, c: char) {
 }
 
 /// Convert a wide-char to a symbol that can be used in our output.
-pub fn char_to_symbol(c: char) -> WString {
+pub fn char_to_symbol(c: char, is_first_in_token: bool) -> WString {
     let mut buff = WString::new();
     let buf = &mut buff;
     if c <= ' ' || c == '\x7F' {
         ctrl_to_symbol(buf, c);
     } else if c < '\u{80}' {
         // ASCII characters that are not control characters
-        ascii_printable_to_symbol(buf, c);
+        ascii_printable_to_symbol(buf, is_first_in_token, c);
     } else if let Some(byte) = decode_byte_from_char(c) {
         sprintf!(=> buf, "\\x%02x", byte);
     } else if ('\u{e000}'..='\u{f8ff}').contains(&c) {

tests/checks/bind.fish

@@ -120,6 +120,15 @@ bind | string match -v '*\e\\[*'
 # CHECK: bind -M bind_mode ctrl-x true
 # CHECK: bind tab 'echo banana'
 
+bind ctrl-#
+bind alt-\#
+bind super-ctrl-~
+bind super-alt-\~
+# CHECKERR: bind: No binding found for key 'ctrl-#'
+# CHECKERR: bind: No binding found for key 'alt-#'
+# CHECKERR: bind: No binding found for key 'super-ctrl-~'
+# CHECKERR: bind: No binding found for key 'super-alt-~'
+
 # Legacy
 bind \cx\cax 'echo foo'
 bind \cx\cax