[CMake] Macro's all and string expansion

[Tristan Carel]

Hi,

While passing a regular expression to macro as parameter, I
experimented strange behaviour:

$ cat bar.cmake
MACRO(FOO regexp)
  IF("foo.bar" MATCHES "${regexp}")
    MESSAGE(STATUS "FOO: match")
  ENDIF("foo.bar" MATCHES "${regexp}")
ENDMACRO(FOO)

IF("foo.bar" MATCHES "foo\\.bar")
  MESSAGE(STATUS "REFERENCE: OK")
ENDIF("foo.bar" MATCHES "foo\\.bar")

FOO("foo\\.bar")
$
$ /usr/bin/cmake --version
cmake version 2.4-patch 6
$
$ cmake -P bar.cmake
-- REFERENCE: OK
CMake Error: Invalid escape sequence \.
CMake Error: Syntax error in cmake code at
/tmp/bar.cmake:11:
syntax error, unexpected cal_ERROR, expecting $end (5), when parsing
string "foo\.bar"

I must increase the escape level to make the macro's call working:
  FOO("foo\\\\.bar")

To figure out what is going on, I tried another test: a macro which
call another one, passing its input argument.

$ cat foobar.cmake
MACRO(BAR regexp)
  IF("foo.bar" MATCHES ${regexp})
    MESSAGE(STATUS "BAR: match")
  ENDIF("foo.bar" MATCHES ${regexp})
ENDMACRO(BAR)

MACRO(FOO regexp)
  BAR(${regexp})
ENDMACRO(FOO)

IF("foo.bar" MATCHES "foo\\.bar")
  MESSAGE(STATUS "REFERENCE: OK")
ENDIF("foo.bar" MATCHES "foo\\.bar")

FOO("foo\\\\\\\\.bar")
$

As you can see, I have to escaped one more time to make it works,
otherwise I have the same error as above. So I guess escaped
characters are expanded at each macro's call but I don't understand
why it should be the case.

I tried to surround ${regexp} with quotes, without success.

The behaviour is exactly the same with CMake cvs built this morning.

I want to be able to pass non-tricky regular expressions to macros,
firstly because escaping stuff is very annoying and secondly because a
user shouldn't need to know macro's internal mechanisms to use it.

If it is not a bug, can something clarify this to me?
Thx by advance.
-- 
Tristan Carel
Music with dinner is an insult both to the cook and the violinist.
http://www.tristancarel.com