[PATCH 09/13] gdb: remove backslash-newline handling from cp_parse_escape

[Simon Marchi <simon.marchi@efficios.com>]

From: Simon Marchi <simon.marchi@polymtl.ca>

cp_parse_escape returns -2 when the backslash is followed by a newline.
In source code, a backslash-newline is a line splice, which can appear
anywhere, including in string literals.  But cp_parse_escape does not
need to handle that.

This comes from GDB's old generic parse_escape function, where a negative
value told the caller to treat the sequence as nothing at all, emulating a
line splice.  lex_char_literal doesn't even handle that: it uses the
returned -2 as the value of the character, so C<'\<newline>'> canonicalizes
to "C<(char)-2>".

Remove the special case.  A backslash followed by a newline is now
handled like any other unknown escape sequence, giving the character
following the backslash.  So now, C<'\<newline>'> canonicalizes to
"C<(char)10>".  cp_parse_escape doesn't reject unknown escape sequences
in general, which is acceptable, and we don't expect to see this one in
practice anyway.

Update the comment of cp_parse_escape, which mentioned the negative
value for backslash-newline.

Change-Id: I25a4587309f201ac8da2ae87361ad4f3e89d7327
---
 gdb/cp-name-parser.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/gdb/cp-name-parser.c b/gdb/cp-name-parser.c
index 4c5f18c9851f..931f74e8ed51 100644
--- a/gdb/cp-name-parser.c
+++ b/gdb/cp-name-parser.c
@@ -470,9 +470,6 @@ c_parse_backslash (int host_char, int *target_char)
    is updated past the characters we use.  The value of the
    escape sequence is returned.
 
-   A negative value means the sequence \ newline was seen,
-   which is supposed to be equivalent to nothing at all.
-
    If \ is followed by a null character, we return a negative
    value and leave the string pointer pointing at the null character.
 
@@ -489,8 +486,6 @@ cp_parse_escape (const char **string_ptr)
   else
     switch (c)
       {
-      case '\n':
-	return -2;
       case 0:
 	(*string_ptr)--;
 	return 0;
-- 
2.56.0