Fix decoding of ASCII strings with embedded CR characters

* src/coding.c (string_ascii_p): Return a negative value if an
all-ASCII string STR includes the CR character, otherwise a
positive value.
(code_convert_string): If the string is ASCII, but includes CR
characters, use the fast path only if EOL doesn't need to be
decoded.  (Bug#40519)

* test/src/coding-tests.el (coding-nocopy-ascii): Add more tests
for bug#40519.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/coding.c b/src/coding.c
index 24a832ff3ee..c24c70c0899 100644
--- a/src/coding.c
+++ b/src/coding.c
@@ -9471,7 +9471,7 @@ not fully specified.)  */)
   return code_convert_region (start, end, coding_system, destination, 1, 0);
 }
 
-/* Non-zero if STR contains only characterss in the 0..127 range.
+/* Non-zero if STR contains only characters in the 0..127 range.
    Positive if STR includes characters that don't need EOL conversion
    on decoding, negative otherwise.  */
 static int
@@ -9523,7 +9523,7 @@ code_convert_string (Lisp_Object string, Lisp_Object coding_system,
   if (EQ (dst_object, Qt))
     {
       /* Fast path for ASCII-only input and an ASCII-compatible coding:
-         act as identity.  */
+         act as identity if no EOL conversion is neede.  */
       int ascii_p;
       Lisp_Object attrs = CODING_ID_ATTRS (coding.id);
       if (! NILP (CODING_ATTR_ASCII_COMPAT (attrs))