> Without the '$\\' syntax, I get everything on one line
I didn't understand that until I'd tried it. With just \ as line ending, the
G_TRACE macro definition ends up on one line. With \\ as line ending, it ends
up with \\ as line ending. With $\\ as line ending, it ends up with \, line
you'd want.
> How can I avoid that?
This seems to work:
martind@sirius:~/tmp/vanem-2023-04-14$ cat Makefile
g_trace.h: Makefile; $(file > $@,$(trace_h))
\ = \
define trace_h
#define G_TRACE(level, fmt, ...) $\\
do { $\\
if (_g_trace_level() >= level) { $\\
_g_trace_color (TRACE_COLOUR_START); $\\
# ....
endef
martind@sirius:~/tmp/vanem-2023-04-14$ make --warn-undefined-variables; cat
g_trace.h; rm g_trace.h
make: 'g_trace.h' is up to date.
#define G_TRACE(level, fmt, ...) \
do { \
if (_g_trace_level() >= level) { \
_g_trace_color (TRACE_COLOUR_START); \
# ....
martind@sirius:~/tmp/vanem-2023-04-14$
It works with:
\ =
... too but not with:
\ = \\
... nor with:
A = \
... nor with A set to nothing or A or whatever. That's with:
martind@sirius:~/tmp/vanem-2023-04-14$ make --version
GNU Make 4.4.0.91
________________________________
From: bug-make-bounces+martin.dorey=hds....@gnu.org
<bug-make-bounces+martin.dorey=hds....@gnu.org> on behalf of Gisle Vanem
<gva...@yahoo.no>
Sent: Friday, April 14, 2023 02:38
To: bug-make <bug-make@gnu.org>
Subject: Warnings on '$\\'
***** EXTERNAL EMAIL *****
In a makefile I have the need to generate a
multi-line C-macro (for use in Glib):
g_trace.h: Makefile
$(file > $@,$(trace_h))
define trace_h
#define G_TRACE(level, fmt, ...) $\\
do { $\\
if (_g_trace_level() >= level) { $\\
_g_trace_color (TRACE_COLOUR_START); $\\
# ....
endef
Without the '$\\' syntax, I get everything on one line
which I'd rather not want. With the '$\\' endings, g_trace.h
is perfect.
But with 'MAKEFLAGS += --warn-undefined-variables', I get a
bunch of warnings:
'reference to undefined variable '\''
How can I avoid that?
I read upon '.WARNINGS', but fail to see how to use that in this case.
--
--gv
