Re: [fpc-devel] Why: "Can't take the address of constant expressions" here?
On 1/13/23 5:35 AM, Bart via fpc-devel wrote: On Fri, Jan 13, 2023 at 11:13 AM wkitty42--- via fpc-devel wrote: First of all, adding a 'end;" for the "with" compiles under Linux. That's because widestring=unicodestring on Linux. i'm a little surprised there is no "mismatched begin/end" error with the caret pointing to the 2nd begin... -- That's a copy/paste error.by me. The original code had about 10 more function calls and then a closing end for the "with WideStringManager do begin " oh! that would explain it :lol: -- NOTE: No off-list assistance is given without prior approval. *Please keep mailing list traffic on the list where it belongs!* ___ fpc-devel maillist - fpc-devel@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel
Re: [fpc-devel] Why: "Can't take the address of constant expressions" here?
On Fri, Jan 13, 2023 at 11:13 AM wkitty42--- via fpc-devel wrote: > > > First of all, adding a 'end;" for the "with" compiles under Linux. > > That's because widestring=unicodestring on Linux. > > i'm a little surprised there is no "mismatched begin/end" error with the caret > pointing to the 2nd begin... > > -- That's a copy/paste error.by me. The original code had about 10 more function calls and then a closing end for the "with WideStringManager do begin " -- Bart ___ fpc-devel maillist - fpc-devel@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel
Re: [fpc-devel] Why: "Can't take the address of constant expressions" here?
On 1/12/23 10:29 AM, Mattias Gaertner via fpc-devel wrote: On Wed, 11 Jan 2023 23:58:34 +0100 Bart via fpc-devel wrote: [...] begin with WideStringManager do begin writeln(1); Wide2AnsiMoveProc(pwidechar(WSource),RawByteString(ADest), CP_UTF8, Length(WSource)); writeln(2); Ansi2WideMoveProc(PChar(ASource), CP_UTF8, UDest, Length(ASource)); //<< test.lpr(24,53) Error: Can't take the address of constant expressions (caret behind UDest) end. First of all, adding a 'end;" for the "with" compiles under Linux. That's because widestring=unicodestring on Linux. i'm a little surprised there is no "mismatched begin/end" error with the caret pointing to the 2nd begin... -- NOTE: No off-list assistance is given without prior approval. *Please keep mailing list traffic on the list where it belongs!* ___ fpc-devel maillist - fpc-devel@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel
Re: [fpc-devel] Why: "Can't take the address of constant expressions" here?
Am 13.01.2023 um 01:05 schrieb Bart via fpc-devel: The issue is indeed the conversion from UnicodeString to WideString which is not allowed for a var/out parameter. That the compiler doesn't use the error “Call by var for arg no. 3 has to match exactly: Got "UnicodeString" expected "WideString"” is due to Ansi2WideMoveProc() being a function pointer. The code that determines that error is not called in that case, instead the other is caused essentially as a last resort. Thanks for explaining. You can report a bug with the following sample to hopefully improve this: Reported as issue #40106 Thank you. Regards, Sven ___ fpc-devel maillist - fpc-devel@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel
Re: [fpc-devel] Why: "Can't take the address of constant expressions" here?
> The issue is indeed the conversion from UnicodeString to WideString
> which is not allowed for a var/out parameter. That the compiler doesn't
> use the error “Call by var for arg no. 3 has to match exactly: Got
> "UnicodeString" expected "WideString"” is due to Ansi2WideMoveProc()
> being a function pointer. The code that determines that error is not
> called in that case, instead the other is caused essentially as a last
> resort.
Thanks for explaining.
>
> You can report a bug with the following sample to hopefully improve this:
>
Reported as issue #40106
On Thu, Jan 12, 2023 at 9:39 PM Sven Barth wrote:
>
> Am 11.01.2023 um 23:58 schrieb Bart via fpc-devel:
> > Given the following program (an excerpt form a test program for a
> > bugreport about the fpwidestring unit):
> >
> > ===
> > program test;
> > {$codepage utf8}
> > {$mode objfpc}
> > {$h+}
> >
> > uses
> >FpWideString;
> >
> > var
> >WSource: WideString = 'source';
> >USource: UnicodeString = 'source';
> >WDest: WideString = '' ;
> >UDest: UnicodeString = '';
> >ASource: AnsiString = 'source';
> >ADest: AnsiString = '';
> >P: array[0..99] of AnsiChar;
> >
> > begin
> >with WideStringManager do
> >begin
> > writeln(1);
> > Wide2AnsiMoveProc(pwidechar(WSource),RawByteString(ADest),
> > CP_UTF8, Length(WSource));
> > writeln(2);
> > Ansi2WideMoveProc(PChar(ASource), CP_UTF8, UDest,
> > Length(ASource)); //<< test.lpr(24,53) Error: Can't take the address
> > of constant expressions (caret behind UDest)
> > end.
> >
> > C:\Users\Bart\LazarusProjecten\bugs\Console\fpwidestring>fpc test.lpr
> > Free Pascal Compiler version 3.3.1 [2022/10/11] for i386
> > Copyright (c) 1993-2022 by Florian Klaempfl and others
> > Target OS: Win32 for i386
> > Compiling test.lpr
> > test.lpr(24,53) Error: Can't take the address of constant expressions
> > ...
> > UDest is of the wrong type here, it compiles fine with WDest (WideString).
> > I just don't understand the "Can't take the address of constant expressions"
> > I would have expected something like "Call by var for arg no. 3 has to
> > match exactly: Got "UnicodeString" expected "WideString""
>
> The issue is indeed the conversion from UnicodeString to WideString
> which is not allowed for a var/out parameter. That the compiler doesn't
> use the error “Call by var for arg no. 3 has to match exactly: Got
> "UnicodeString" expected "WideString"” is due to Ansi2WideMoveProc()
> being a function pointer. The code that determines that error is not
> called in that case, instead the other is caused essentially as a last
> resort.
>
> You can report a bug with the following sample to hopefully improve this:
>
> === code begin ===
>
> program tunicode;
>
> var
>Str: UnicodeString = 'Foobar';
>
> procedure Test(var aArg: WideString);
> begin
>
> end;
>
> var
>Func: procedure(var aArg: WideString) = Nil;
> begin
>Test(Str);
>Func(Str);
> end.
>
> === code end ===
>
> Regards,
> Sven
--
Bart
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Re: [fpc-devel] Why: "Can't take the address of constant expressions" here?
Am 11.01.2023 um 23:58 schrieb Bart via fpc-devel:
Given the following program (an excerpt form a test program for a
bugreport about the fpwidestring unit):
===
program test;
{$codepage utf8}
{$mode objfpc}
{$h+}
uses
FpWideString;
var
WSource: WideString = 'source';
USource: UnicodeString = 'source';
WDest: WideString = '' ;
UDest: UnicodeString = '';
ASource: AnsiString = 'source';
ADest: AnsiString = '';
P: array[0..99] of AnsiChar;
begin
with WideStringManager do
begin
writeln(1);
Wide2AnsiMoveProc(pwidechar(WSource),RawByteString(ADest),
CP_UTF8, Length(WSource));
writeln(2);
Ansi2WideMoveProc(PChar(ASource), CP_UTF8, UDest,
Length(ASource)); //<< test.lpr(24,53) Error: Can't take the address
of constant expressions (caret behind UDest)
end.
C:\Users\Bart\LazarusProjecten\bugs\Console\fpwidestring>fpc test.lpr
Free Pascal Compiler version 3.3.1 [2022/10/11] for i386
Copyright (c) 1993-2022 by Florian Klaempfl and others
Target OS: Win32 for i386
Compiling test.lpr
test.lpr(24,53) Error: Can't take the address of constant expressions
...
UDest is of the wrong type here, it compiles fine with WDest (WideString).
I just don't understand the "Can't take the address of constant expressions"
I would have expected something like "Call by var for arg no. 3 has to
match exactly: Got "UnicodeString" expected "WideString""
The issue is indeed the conversion from UnicodeString to WideString
which is not allowed for a var/out parameter. That the compiler doesn't
use the error “Call by var for arg no. 3 has to match exactly: Got
"UnicodeString" expected "WideString"” is due to Ansi2WideMoveProc()
being a function pointer. The code that determines that error is not
called in that case, instead the other is caused essentially as a last
resort.
You can report a bug with the following sample to hopefully improve this:
=== code begin ===
program tunicode;
var
Str: UnicodeString = 'Foobar';
procedure Test(var aArg: WideString);
begin
end;
var
Func: procedure(var aArg: WideString) = Nil;
begin
Test(Str);
Func(Str);
end.
=== code end ===
Regards,
Sven
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Re: [fpc-devel] Why: "Can't take the address of constant expressions" here?
On Wed, 11 Jan 2023 23:58:34 +0100
Bart via fpc-devel wrote:
> Given the following program (an excerpt form a test program for a
> bugreport about the fpwidestring unit):
>
> ===
> program test;
> {$codepage utf8}
> {$mode objfpc}
> {$h+}
>
> uses
> FpWideString;
>
> var
> WSource: WideString = 'source';
> USource: UnicodeString = 'source';
> WDest: WideString = '' ;
> UDest: UnicodeString = '';
> ASource: AnsiString = 'source';
> ADest: AnsiString = '';
> P: array[0..99] of AnsiChar;
>
> begin
> with WideStringManager do
> begin
> writeln(1);
> Wide2AnsiMoveProc(pwidechar(WSource),RawByteString(ADest),
> CP_UTF8, Length(WSource));
> writeln(2);
> Ansi2WideMoveProc(PChar(ASource), CP_UTF8, UDest,
> Length(ASource)); //<< test.lpr(24,53) Error: Can't take the address
> of constant expressions (caret behind UDest)
> end.
First of all, adding a 'end;" for the "with" compiles under Linux.
That's because widestring=unicodestring on Linux.
On Windows widestring is not a unicodestring and thus it can't be
passed to a var parameter.
https://wiki.freepascal.org/Widestrings
Mattias
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Re: [fpc-devel] Why: "Can't take the address of constant expressions" here?
On Wed, 11 Jan 2023, Bart via fpc-devel wrote:
Given the following program (an excerpt form a test program for a
bugreport about the fpwidestring unit):
===
program test;
{$codepage utf8}
{$mode objfpc}
{$h+}
uses
FpWideString;
var
WSource: WideString = 'source';
USource: UnicodeString = 'source';
WDest: WideString = '' ;
UDest: UnicodeString = '';
ASource: AnsiString = 'source';
ADest: AnsiString = '';
P: array[0..99] of AnsiChar;
begin
with WideStringManager do
begin
writeln(1);
Wide2AnsiMoveProc(pwidechar(WSource),RawByteString(ADest),
CP_UTF8, Length(WSource));
writeln(2);
Ansi2WideMoveProc(PChar(ASource), CP_UTF8, UDest,
Length(ASource)); //<< test.lpr(24,53) Error: Can't take the address
of constant expressions (caret behind UDest)
end.
C:\Users\Bart\LazarusProjecten\bugs\Console\fpwidestring>fpc test.lpr
Free Pascal Compiler version 3.3.1 [2022/10/11] for i386
Copyright (c) 1993-2022 by Florian Klaempfl and others
Target OS: Win32 for i386
Compiling test.lpr
test.lpr(24,53) Error: Can't take the address of constant expressions
...
UDest is of the wrong type here, it compiles fine with WDest (WideString).
I just don't understand the "Can't take the address of constant expressions"
I would have expected something like "Call by var for arg no. 3 has to
match exactly: Got "UnicodeString" expected "WideString""
I think that what happens is that the compiler sees that it can convert
widestring to unicodestring and allows a conversion, so it inserts a
conversion node, but the result of the conversion is a constant expresson
so it generates an error in a later stage of compilation.
But my knowledge is limited, someone else will need to confirm this.
Michael.
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[fpc-devel] Why: "Can't take the address of constant expressions" here?
Given the following program (an excerpt form a test program for a
bugreport about the fpwidestring unit):
===
program test;
{$codepage utf8}
{$mode objfpc}
{$h+}
uses
FpWideString;
var
WSource: WideString = 'source';
USource: UnicodeString = 'source';
WDest: WideString = '' ;
UDest: UnicodeString = '';
ASource: AnsiString = 'source';
ADest: AnsiString = '';
P: array[0..99] of AnsiChar;
begin
with WideStringManager do
begin
writeln(1);
Wide2AnsiMoveProc(pwidechar(WSource),RawByteString(ADest),
CP_UTF8, Length(WSource));
writeln(2);
Ansi2WideMoveProc(PChar(ASource), CP_UTF8, UDest,
Length(ASource)); //<< test.lpr(24,53) Error: Can't take the address
of constant expressions (caret behind UDest)
end.
C:\Users\Bart\LazarusProjecten\bugs\Console\fpwidestring>fpc test.lpr
Free Pascal Compiler version 3.3.1 [2022/10/11] for i386
Copyright (c) 1993-2022 by Florian Klaempfl and others
Target OS: Win32 for i386
Compiling test.lpr
test.lpr(24,53) Error: Can't take the address of constant expressions
...
UDest is of the wrong type here, it compiles fine with WDest (WideString).
I just don't understand the "Can't take the address of constant expressions"
I would have expected something like "Call by var for arg no. 3 has to
match exactly: Got "UnicodeString" expected "WideString""
--
Bart
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