Match w32 paths in grep sans --null hits (Bug#32051)

* lisp/progmodes/grep.el (grep-regexp-alist): Add an optional part to
match paths starting with C: (other drive letters).
* test/lisp/progmodes/compile-tests.el
(compile-tests--grep-regexp-testcases)
(compile-tests--grep-regexp-tricky-testcases)
(compile-test-grep-regexps): New tests.
(compile--test-error-line): Return `compilation-message'.

1 files changed, 3 insertions, 1 deletions

diff --git a/lisp/progmodes/grep.el b/lisp/progmodes/grep.el
index da09c900e58..0bfabd5f3fe 100644
--- a/lisp/progmodes/grep.el
+++ b/lisp/progmodes/grep.el
@@ -379,7 +379,9 @@ Notice that using \\[next-error] or \\[compile-goto-error] modifies
               ;; 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.
-              "\\(?1:[^\n:]+?[^\n/:]\\):[\t ]*\\(?2:[1-9][0-9]*\\)[\t ]*:"
+              "\\(?1:"
+              "\\(?:[a-zA-Z]:\\)?" ; Allow "C:..." for w32.
+              "[^\n:]+?[^\n/:]\\):[\t ]*\\(?2:[1-9][0-9]*\\)[\t ]*:"
               "\\)")
      1 2
      ;; Calculate column positions (col . end-col) of first grep match on a line