• via Digitalmars-d-bugs (49/49) Aug 29 2016 https://issues.dlang.org/show_bug.cgi?id=16444

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

https://issues.dlang.org/show_bug.cgi?id=16444

          Issue ID: 16444
           Summary: Less noisy error messages if built-in method is
                     disable (e.g. opAssign)
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: dmd
          Assignee: nobody puremagic.com
          Reporter: greensunny12 gmail.com

When a builtin-in method like opAssign is disabled, the error messages are
quite noisy:

struct A
{
     disable void opAssign(Other)(Other other);
}

pure nothrow  safe  nogc unittest
{
    A a;
    a = A();
}

foo.d(16): Error: function foo.A.opAssign!(A).opAssign is not callable because
it is annotated with  disable
foo.d(16): Error: pure function 'foo.__unittestL13_1' cannot call impure
function 'foo.A.opAssign!(A).opAssign'
foo.d(16): Error: safe function 'foo.__unittestL13_1' cannot call system
function 'foo.A.opAssign!(A).opAssign'
foo.d(16): Error:  nogc function 'foo.__unittestL13_1' cannot call non- nogc
function 'foo.A.opAssign!(A).opAssign'
foo.d(16): Error: function 'foo.A.opAssign!(A).opAssign' is not nothrow
foo.d(13): Error: function 'foo.__unittestL13_1' is nothrow yet may throw


There is a trick that is used in https://github.com/dlang/phobos/pull/4755, one
can simply annotate the disabled function with all attributes:

struct B
{
    pure nothrow  safe  nogc  disable void opAssign(Other)(Other other);
}

pure nothrow  safe  nogc unittest
{
    B b;
    b = B();
}

foo.d(16): Error: function foo.B.opAssign!(B).opAssign is not callable because
it is annotated with  disable

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