The following Makefile illustrates the issue:

$ cat >Makefile <<EOF

all:

echo "abc" | grep "b"

.PHONY: all

$ make all # works as expected

$ make all > /dev/null

grep: (standard input): Invalid argument

make: *** [Makefile:2: all] Error 2

The bug was introduced by commit 4fa6f48b573267e758650e114ec158d97916411e (introducing the usage of splice), which was first released in grep version 2.27.

My environment:

$ make --version

GNU Make 4.2.1

Built for x86_64-pc-linux-gnu

License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>

This is free software: you are free to change and redistribute it.

There is NO WARRANTY, to the extent permitted by law.

$ grep --version

grep (GNU grep) 2.27

License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.

This is free software: you are free to change and redistribute it.

There is NO WARRANTY, to the extent permitted by law.

Written by Mike Haertel and others, see <http://git.sv.gnu.org/cgit/grep.git/tree/AUTHORS>.

Patch attached.

Benno Fünfstück