• via Digitalmars-d-bugs (32/32) Dec 29 2014 https://issues.dlang.org/show_bug.cgi?id=13909

via Digitalmars-d-bugs <digitalmars-d-bugs puremagic.com> writes:

https://issues.dlang.org/show_bug.cgi?id=13909

          Issue ID: 13909
           Summary: A problem with immutable zip + assocArray
           Product: D
           Version: D2
          Hardware: x86
                OS: Windows
            Status: NEW
          Severity: normal
          Priority: P1
         Component: Phobos
          Assignee: nobody puremagic.com
          Reporter: bearophile_hugs eml.cc

I don't understand what's going on here. The line where aa2 is initialized gets
accepted, while the initialization of aa5 gets refused, despite in both cases
they use zipped keys/values from immutable associative arrays:


import std.array: assocArray;
import std.range: zip;
immutable string[const string] aa1, aa2, aa4, aa5;
static this() pure {
    immutable aa3 = ["a":"b"];
    aa2 = aa3.byValue.zip(aa3.byKey).assocArray; // OK
    aa4 = ["a":"b"];
    aa5 = aa4.byValue.zip(aa4.byKey).assocArray; // Error
}
void main() {}


dmd 2.067alpha gives:

...\dmd2\src\phobos\std\array.d(281,11): Error: cannot modify const expression
aa[t.__expand_field_0]
test.d(8,37): Error: template instance std.array.assocArray!(Zip!(Result,
Result)) error instantiating

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