[fpc-pascal]trouble with {$IF ...}

[David Emerson]

I would like to do some very basic boolean operations within compiler directives. $IF does not seem to work reliably. See below:

C:\fpc\test>fpc directive_test -Sm
Free Pascal Compiler version 1.0.10 [2003/06/27] for i386
[...]
User defined: =========================
User defined: $define x:=17
User defined: !!! (x=5) = TRUE even though i set x:=17
User defined: .   (x>50) = false   (good, x=17)
User defined: !!! (x<50) = FALSE even though i set x:=17
User defined: !!! ($if 1 AND 0) = TRUE
User defined: =========================
User defined: $define zero:=0
User defined: !!! ($if zero) = TRUE
User defined: !!! ($if 0) = TRUE
User defined: and now the exact same test again...
User defined: .   ($if 0) = false
User defined: =========================
User defined: $define apples
User defined: !!! ($ifdef oranges or apples) = FALSE   :-(
User defined: =========================
Linking directive_test.exe
68 Lines compiled, 1.2 sec

I know boolean operators are not supported for $ifdef, but it would sure be nice.

The most baffling part is where {$IF 0} = true and then the same {$IF 0} = false. It seems to be related to the test done just prior to it -- If I follow the 'zero' test with the {$IF 0} test, the latter doesn't work.


Here is the source:

begin

{$info =========================}

{$define x:=17}
{$info $define x:=17}
{$if x=5}
   {$info !!! (x=5) = TRUE even though i set x:=17}
{$else}
   {$info .   (x=5) = false   (good, x=17)}
{$endif}

{$if x>50}
   {$info !!! (x>50) = TRUE even though i set x:=17}
{$else}
   {$info .   (x>50) = false   (good, x=17)}
{$endif}

{$if x<50}
   {$info .   (x<50) = true   (good, x=17)}
{$else}
   {$info !!! (x<50) = FALSE even though i set x:=17}
{$endif}

{$if 1 AND 0}
   {$info !!! ($if 1 AND 0) = TRUE}
{$else}
   {$info .   ($if 1 AND 0) = false}
{$endif}

{$info =========================}

{$define zero:=0}
{$info $define zero:=0}

{$if zero}
   {$info !!! ($if zero) = TRUE}
{$else}
   {$info .   zero returned false}
{$endif}

{$if 0}
   {$info !!! ($if 0) = TRUE}
{$else}
   {$info .   ($if 0) = false}
{$endif}

{$info and now the exact same test again...}

{$if 0}
   {$info !!! ($if 0) = TRUE}
{$else}
   {$info .   ($if 0) = false}
{$endif}

{$info =========================}

{$define apples}
{$info $define apples}

{$ifdef oranges or apples}
   {$info .   ($ifdef oranges or apples) = true}
{$else}
   {$info !!! ($ifdef oranges or apples) = FALSE   :-( }
{$endif}

{$info =========================}

end.