[CMake] how to set 2 additional compile flags on target (VS2005)

[Bram de Greve]

Hi,

I'm trying to use precompiled headers with VS2005.  Therefore, I need to
set on the target two additional compile flags: /Yu with the header to
be precompiled, and /Fp with the path of the resulting PCH.
But whatever I try, cmake will only set one of them.

The following will only set the second compile flag.  in this case /Fp. 
If I reverse the lines, it will set /Yu. 

set_target_properties(
    ${target}
    PROPERTIES
    COMPILE_FLAGS /Yu"${hdrfile}"
    COMPILE_FLAGS /Fp"${pchpath}"
)

If I put both compile flags on one line as following, it is not accepted
by CMake as there's an incorrect number of arguments:

set_target_properties(
    ${target}
    PROPERTIES
    COMPILE_FLAGS /Yu"${hdrfile}" /Fp"${pchpath}"
)

Splitting it into two statements as following, has the same effect (only
setting the second one)

set_target_properties(
    ${target}
    PROPERTIES
    COMPILE_FLAGS /Yu"${hdrfile}"
)
set_target_properties(
    ${target}
    PROPERTIES
    COMPILE_FLAGS /Fp"${pchpath}"
)

Using set_property with APPEND, has the effect that it concatenates both
flags with a semicolon, something like /Yufoobar.h;/Fpfoobar.pch, so
that VS thinks the header to be precompiled is called
"foobar.h;/Fpfoobar.pch".  Err, wrong =)

set_property(
    TARGET ${target}
    APPEND PROPERTY
    COMPILE_FLAGS /Yu"${hdrfile}" /Fp"${pchpath}")

It even has this same concatenation effect when I split it into two
statements:

set_property(
    TARGET ${target}
    APPEND PROPERTY
    COMPILE_FLAGS /Fp"${pchpath}")
set_property(
    TARGET ${target}
    APPEND PROPERTY
    COMPILE_FLAGS /Yu"${hdrfile}")

And when I leave out the APPEND, we're back to square one where it only
sets the second compiler flag:

set_property(
    TARGET ${target}
    PROPERTY
    COMPILE_FLAGS /Fp"${pchpath}")
set_property(
    TARGET ${target}
    PROPERTY
    COMPILE_FLAGS /Yu"${hdrfile}")

So, my question obviously is: what's the proper way to set TWO (or more)
additional compiler flags on na target.

Thanks in advance,
Bram

PS: Technically, it's not really necessary to set /Fp, as the default is
fine, but it still strikes me as cumbersome.