bug#27873: 26.0.50; M-x grep broken

[npostavs]

tags 27873 + patch
quit

Eric Hanchrow <eric.hanchrow@gmail.com> writes:

> This displayed a *grep* buffer that looked something like I expected,
> but:
>
> * instead of there being exactly one line with some underlining
> (indicating a "hit"), there were a bunch: the one I expected, as well
> as a few before it like this:
>
> grep: git-repositories: Is a directory
> grep: guix: Is a directory
> grep: homedir: Is a directory
> grep: homework: Is a directory
> grep: iTunesDSM: Is a directory
> grep: jessie64: Is a directory
> grep: local: Is a directory
> grep: log: Is a directory
> grep: mygo: Is a directory
> grep: node_modules: Is a directory
> grep: perl5: Is a directory
> phonetic-alphabet.txt1:Stolen from 
> http://www.fourmilab.ch/documents/phoneticalphabet/
> grep: pprof: Is a directory
>
> You can't tell from what I've pasted above, but the 9 "Is a directory"
> lines before the actual hit were red and underlined, just like the
> match was.
>
> * Hitting C-x `, instead of visiting the file with the hit, put a
> nine-line-high prompt in the minibuffer, as if it was asking me which
> directory to find the file in a directory with a really weird name.
> (You can see some evedince of this in the "Recent messages" stuff below).

> https://debbugs.gnu.org/cgi/bugreport.cgi?bug=27840 is a similar report from 
> a few days ago.

It's not a duplicate though, this bug is because I thought using --null
would make it possible to get filenames containing newlines
unambiguously, but I was wrong.  Here's a patch, also covers a couple of
minor issues that came up later in Bug#6843.

>From a6fae71f7f1ea5774a85f4b4238c9d7e4ed4e132 Mon Sep 17 00:00:00 2001
From: Noam Postavsky <npostavs@gmail.com>
Date: Sun, 30 Jul 2017 11:07:01 -0400
Subject: [PATCH v1] Don't take multiples lines of grep output as a single
 filename (Bug#27873)

* lisp/progmodes/grep.el (grep-with-null-regexp-alist): Exclude
newlines from the filename part of the regexp.  We must assume
filenames don't have newlines to avoid ambiguity with "foo is a
directory" messages.  Use 'face nil' instead of 'face unspecified',
the latter causes errors (albeit demoted to messsages).  Also renumber
FILE and LINE regexp groups to match the without-null regexp.
(grep-without-null-regexp-alist): Rename from
`grep-fallback-regexp-alist'.
---
 lisp/progmodes/grep.el | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/lisp/progmodes/grep.el b/lisp/progmodes/grep.el
index 4723290fbe..483a1c49ff 100644
--- a/lisp/progmodes/grep.el
+++ b/lisp/progmodes/grep.el
@@ -384,16 +384,22 @@ (defconst grep--regexp-alist-column
               (mend (and mbeg (next-single-property-change mbeg 
'font-lock-face nil end))))
          (when mend
            (- mend beg)))))))
+
 (defconst grep--regexp-alist-bin-matcher
   '("^Binary file \\(.+\\) matches$" 1 nil nil 0 1))
+
 (defconst grep-with-null-regexp-alist
-  `(("^\\([^\0]+\\)\\(\0\\)\\([0-9]+\\)\\([\0:]\\)" 1 3 
,grep--regexp-alist-column nil nil
-     (2 '(face unspecified display ":"))
-     (4 '(face unspecified display ":")))
+  `(;; Use explicit numbering to keep FILE and LINE groups the same
+    ;; for both regexp alists.
+    ("^\\(?1:[^\0\n]+\\)\\(?3:\0\\)\\(?2:[0-9]+\\)\\(?4:[\0:]\\)"
+     1 2 ,grep--regexp-alist-column nil nil
+     (3 '(face nil display ":"))
+     (4 '(face nil display ":")))
     ,grep--regexp-alist-bin-matcher)
   "Regexp used to match grep hits.
 See `compilation-error-regexp-alist'.")
-(defconst grep-fallback-regexp-alist
+
+(defconst grep-without-null-regexp-alist
   `(;; Use a tight regexp to handle weird file names (with colons
     ;; in them) as well as possible.  E.g., use [1-9][0-9]* rather
     ;; than [0-9]+ so as to accept ":034:" in file names.
@@ -401,7 +407,8 @@ (defconst grep-fallback-regexp-alist
      1 2 ,grep--regexp-alist-column)
     ,grep--regexp-alist-bin-matcher)
   "Regexp used to match grep hits when `--null' is not supported.
-See `compilation-error-regexp-alist'.")
+See `compilation-error-regexp-alist' and
+`grep-use-null-filename-separator'.")
 
 (defvaralias 'grep-regex-alist 'grep-with-null-regexp-alist)
 (make-obsolete-variable
-- 
2.11.1