• SrMordred (15/15) May 24 2018 int[] a;
• Adam D. Ruppe (3/7) May 24 2018 phobos automatically decodes utf8 into dchars. This can throw a
• SrMordred (5/13) May 24 2018 Oh its the utf8 decode thing.
• Jonathan M Davis (10/23) May 24 2018 It happens with any "narrow string" - i.e. any array of char or dchar. Y...
• Jonathan M Davis (9/24) May 24 2018 Because arrays of char and wchar are treated as ranges of dchar.
• SrMordred (1/2) May 24 2018 That part that I didnt know, thanks! :)

SrMordred <patric.dexheimer gmail.com> writes:

int[] a;
int[] b;

() nogc {
    foreach(v ; chain( a,b ) ) printf("%d\n", v);
}();

//Ok, everything fine;

char[] a;
char[] b;

() nogc {
    foreach(v ; chain( a,b ) ) printf("%c\n", v);
}();

//Error:  nogc delegate onlineapp.main.__lambda1 cannot call 
non- nogc function std.range.chain!(char[], 
char[]).chain.Result.front

Why?

Adam D. Ruppe <destructionator gmail.com> writes:

On Thursday, 24 May 2018 at 23:55:24 UTC, SrMordred wrote:
 //Error:  nogc delegate onlineapp.main.__lambda1 cannot call 
 non- nogc function std.range.chain!(char[], 
 char[]).chain.Result.front

 Why?

phobos automatically decodes utf8 into dchars. This can throw a 
new utf exception.

SrMordred <patric.dexheimer gmail.com> writes:

On Friday, 25 May 2018 at 00:04:10 UTC, Adam D. Ruppe wrote:
 On Thursday, 24 May 2018 at 23:55:24 UTC, SrMordred wrote:
 //Error:  nogc delegate onlineapp.main.__lambda1 cannot call 
 non- nogc function std.range.chain!(char[], 
 char[]).chain.Result.front

 Why?

 phobos automatically decodes utf8 into dchars. This can throw a 
 new utf exception.

Oh its the utf8 decode thing.
I forgot about it.
I thought that it only decodes when using strings and dchars.

Thanks!

Jonathan M Davis <newsgroup.d jmdavisprog.com> writes:

On Friday, May 25, 2018 00:09:28 SrMordred via Digitalmars-d-learn wrote:
 On Friday, 25 May 2018 at 00:04:10 UTC, Adam D. Ruppe wrote:
 On Thursday, 24 May 2018 at 23:55:24 UTC, SrMordred wrote:
 //Error:  nogc delegate onlineapp.main.__lambda1 cannot call
 non- nogc function std.range.chain!(char[],
 char[]).chain.Result.front

 Why?

 phobos automatically decodes utf8 into dchars. This can throw a
 new utf exception.

 Oh its the utf8 decode thing.
 I forgot about it.
 I thought that it only decodes when using strings and dchars.

It happens with any "narrow string" - i.e. any array of char or dchar. You
can test for it with std.traits.isNarrowString, whose current implementation
is:

enum bool isNarrowString(T) = isSomeString!T && !is(T : const dchar[]);

Basically, unless a range-based function goes out of its way to specialize
for narrow strings and avoids any decoding (and whether that makes any sense
depends on what the function does), it's going to treat any array of char or
wchar as a range of dchar and will throw a UTFException on invalid Unicode.

- Jonathan M Davis

Jonathan M Davis <newsgroup.d jmdavisprog.com> writes:

On Thursday, May 24, 2018 23:55:24 SrMordred via Digitalmars-d-learn wrote:
 int[] a;
 int[] b;

 () nogc {
     foreach(v ; chain( a,b ) ) printf("%d\n", v);
 }();

 //Ok, everything fine;

 char[] a;
 char[] b;

 () nogc {
     foreach(v ; chain( a,b ) ) printf("%c\n", v);
 }();

 //Error:  nogc delegate onlineapp.main.__lambda1 cannot call
 non- nogc function std.range.chain!(char[],
 char[]).chain.Result.front

 Why?

Because arrays of char and wchar are treated as ranges of dchar.
std.primitives.range.front and popFront call std.utf.decode and stride
respectively so that front returns dchar. decode (and possibly stride - I'd
have to check) throw a UTFException on invalid Unicode, and that means that
they allocate with the GC. If you want to avoid the auto-decoding, you have
to use something like std.string.representation or std.utf.byCodeUnit to
wrap the array of chars before passing them to any range-based functions.

- Jonathan M Davis

SrMordred <patric.dexheimer gmail.com> writes:

 Because arrays of char and wchar are treated as ranges of dchar.

That part that I didnt know, thanks! :)