ca65: Include Guard generates "Error: Identifier expected"

Question

Trying to learn how to use the ca65 assembler, I've been battling with making include guards work. Googling and reading the ca65 Users Guide didn't help. Here's a minimal example that produces the error.

$ ls -l
total 16
-rw-r--r--  1 me  staff  60 Oct 22 19:40 65.inc
-rw-r--r--  1 me  staff  55 Oct 22 20:01 test.s
$
$ cat 65.inc
.ifndef _65_INC_
.define _65_INC_

.define NUMBER 1

.endif
$
$ cat test.s
.include "65.inc"
.include "65.inc"

    lda #NUMBER
    rts
$
$ ca65 test.s
65.inc(1): Error: Identifier expected
65.inc(2): Error: Identifier expected
65.inc(4): Error: Identifier expected
65.inc(4): Note: Macro was defined here
$
$ ls -l
total 16
-rw-r--r--  1 me  staff  60 Oct 22 19:40 65.inc
-rw-r--r--  1 me  staff  55 Oct 22 20:01 test.s
$

If I only include 65.inc once in test.s it assembles without problem, as seen here:

$ ls -l
total 16
-rw-r--r--  1 me  staff  60 Oct 22 19:40 65.inc
-rw-r--r--  1 me  staff  37 Oct 22 20:07 test.s
$
$ cat 65.inc
.ifndef _65_INC_
.define _65_INC_

.define NUMBER 1

.endif
$
$ cat test.s
.include "65.inc"

    lda #NUMBER
    rts
$
$ ca65 test.s
$
$ ls -l
total 24
-rw-r--r--  1 me  staff   60 Oct 22 19:40 65.inc
-rw-r--r--  1 me  staff  295 Oct 22 20:07 test.o
-rw-r--r--  1 me  staff   37 Oct 22 20:07 test.s
$
$ ca65 --version
ca65 V2.17 - Git 153bb29

What am I missing?

Answer 1

Somewhat confusingly .ifndef and friends apply to symbols which macros are not (.define defines a macro). Thus a possible workaround is to use a symbol, e.g.

.ifndef _65_INC_
_65_INC_ = 1

.define NUMBER 1

.endif