pure nothrow text(BigInt) too

[dlangBugzillaToGithub]

bearophile_hugs reported this on 2014-05-28T22:45:49Z

Transfered from https://issues.dlang.org/show_bug.cgi?id=12817

CC List

• safety0ff.bugz

Description

In dmd 2.066alpha this compiles and runs:


void main() pure nothrow {
    import std.conv: text;
    int x = 10;
    assert(text(x) == "10");
}


While thios:

void main() pure nothrow {
    import std.bigint: BigInt;
    import std.conv: text;
    BigInt x = 10;
    assert(text(x) == "10");
}


temp.d(5,16): Error: pure function 'D main' cannot call impure function 'std.conv.text!(BigInt).text'
temp.d(5,16): Error: 'std.conv.text!(BigInt).text' is not nothrow
temp.d(1,6): Error: function 'D main' is nothrow yet may throw

[dlangBugzillaToGithub]

safety0ff.bugz commented on 2014-05-28T22:56:33Z

Fixing #6007 may involve a solution which isn't strictly pure (global cache of powers of the base we're converting to.)
This is the solution OpenJDK's biginteger class uses, whether or not we use a global cache or recompute the powers each time is a design issue for the person who decides to fix #6007.

Anyways, I think we should not be so eager in adding pure to the conversion to string unless we have a "trusted pure" available.