Gpc May 2013

gpc@gnu.de

5 participants
3 discussions

Re: variable type cast
by Jay Michael 17 May '13

17 May '13

Adriaan van Os wrote: > > Jay Michael wrote: >> >> gpc version 20070904, based on gcc-3.4.5 (mingw special) >> Given >> type INT16 = INTEGER attribute( size=16 ) ; >> type WORD16 = Cardinal attribute( size=16 ) ; >> var i16 : INT16 ; >> var w16 : WORD16 ; >> why does >> WORD16(I16) := W16 ; >> produce "error: invalid lvalue in assignment"? > > A bug in the compiler. GPC is too picky when it comes to typecasts. Do you have any idea why this case is rejected? The compiler accepted type winbool = boolean attribute( size = 32 ) ; var i : integer ; var wb : winbool ; integer(wb) := 1024 ; integer(wb) := -1 ; integer(wb) := i ; I thought BOOLEAN was an enumeration type. I thought an enumeration type was a second cousin to an unsigned integer. So I thought the only real difference in my case was that I was using 16-bit integers. I was prepared for the compiler to accept the code and insist on generating range checks that I don't want. I'm just puzzled that it wouldn't even accept what looks to me to be just like examples I see posted of "variable type cast".

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variable type cast
by Jay Michael 15 May '13

15 May '13

gpc version 20070904, based on gcc-3.4.5 (mingw special) Given type INT16 = INTEGER attribute( size=16 ) ; type WORD16 = Cardinal attribute( size=16 ) ; var i16 : INT16 ; var w16 : WORD16 ; why does WORD16(I16) := W16 ; produce "error: invalid lvalue in assignment"?

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Fwd: Re: variable type cast
by Maurice Lombardi 13 May '13

13 May '13

-------- Message original -------- Sujet: Re: variable type cast Date : Mon, 13 May 2013 09:11:11 +0200 De : Maurice Lombardi <Maurice.Lombardi(a)ujf-grenoble.fr> Pour : Jay Michael <jmichael_ll(a)yahoo.com> Le 13/05/2013 01:12, Jay Michael a écrit : > gpc version 20070904, based on gcc-3.4.5 (mingw special) > Given > type INT16 = INTEGER attribute( size=16 ) ; > type WORD16 = Cardinal attribute( size=16 ) ; > var i16 : INT16 ; > var w16 : WORD16 ; > why does > WORD16(I16) := W16 ; > produce "error: invalid lvalue in assignment"? First notice tht the other way around I16 := INT16(W16) ; works. Typecasts are C style unportable "extensions" which garble the "write once, compile everywhere" philosophy behind the strong typing principles of Pascal. There is certainly nothing about it in the standards, and I do not know at which point this "lvalue error" crept in first into C, and then into Pascal. Maurice -- Maurice Lombardi Laboratoire Interdisciplinaire de Physique, (ex Spectrometrie Physique) Universite Joseph Fourier de Grenoble, BP87 38402 Saint Martin d'Heres Cedex FRANCE Tel: 33 (0)4 76 51 47 51 Fax: 33 (0)4 76 63 54 95 mailto:Maurice.Lombardi@ujf-grenoble.fr

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Gpc May 2013