Fix qx, `` and <<`` overrides

This resolves two RT tickets:
• #115330 is that qx and `` overrides do not support interpolation.
• #119827 is that <<`` does not support readpipe overrides at all.

The obvious fix for #115330 fixes #119827 at the same time.

When quote-like operators are parsed, after the string has been
scanned S_sublex_push is called, which decides which of two paths
to follow:
1) For things not requiring interpolation, the string is passed to
   tokeq (originally called q, it handles double backslashes and back-
   slashed delimiters) and returned to the parser immediately.
2) For anything that interpolates, the lexer enters a special inter-
   polation mode (LEX_INTERPPUSH) and goes through a more complex
   sequence over the next few calls (e.g., qq"a.$b.c" is turned into
  ‘stringify ( "a." . $ b . ".c" )’).

When commit e3f73d4ed (Oct 2006, perl 5.10) added support for overrid-
ing `` and qx with a readpipe sub, it did so by creating an entersub
op in toke.c and making S_sublex_push follow path no. 1, taking the
result if tokeq and inserting it into the already-constructed op tree
for the sub call.

That approach caused interpolation to be skipped when qx or `` is
overridden.  Furthermore it didn’t touch <<`` at all.

The easiest solution is to let toke.c follow its normal path and
create a backtick op (instead of trying to half-intercept it), and
to deal with override lookup afterwards in ck_backtick, the same way
require overrides are handled.  Since <<`` also turns into a backtick
op, it gets handled too that way.

1 files changed, 0 insertions, 1 deletions

diff --git a/embed.fnc b/embed.fnc
index 9fed8b4113..14a920542a 100644
--- a/embed.fnc
+++ b/embed.fnc
@@ -2258,7 +2258,6 @@ s	|char*	|force_strict_version	|NN char *s
 s	|char*	|force_word	|NN char *start|int token|int check_keyword \
 				|int allow_pack
 s	|SV*	|tokeq		|NN SV *sv
-s	|void	|readpipe_override|
 sR	|char*	|scan_const	|NN char *start
 iR	|SV*	|get_and_check_backslash_N_name|NN const char* s \
 				|NN const char* const e