typeMerge should take modifiers into account when searching for common base class

[quickfur]

Fixes issue 15638.

The problem appears to be that typeMerge does not copy modifiers over when searching for a common base class, so it tries to test implicit convertibility from const(derivedClass) to (non-const) BaseClass, which fails, thus it fails to find the common base class as const(BaseClass).

[dlang-bot]

Fix	Bugzilla	Description
✓	15638	no common type for const classes

[PetarKirov]

Looks good. Maybe it's also a good idea to test:

B mb;
C mc;
const B cb
const C cc;
immutable B ib;
immutable C ic;

auto a1 = true? mb : mc; // const A
auto a2 = true? cb : ic;  // const A
auto a3 = true? mb : ic; // const A
// ...

const(A)[] arr1 = new B[10];
const(A)[] arr2 = new const(B)[10];
const(A)[] arr3 = new immutable(B)[10];
// ...

// I'm not sure if this should work:
const(A)[] concat1 = new const(A)[] ~ new immutable(C)[];
//...

[quickfur]

Good point, the case of x ? const(B) : immutable(C) still does not work. Will look into it more.
Edit: Actually, it does work; I just botched the test code. Will add a few more test cases and push.

[quickfur]

Found that:

const(A)[] concat1 = new const(A)[] ~ new immutable(C)[];

does not work, but this does:

const(A)[] concat1 = new const(A)[1] ~ new immutable(C)[1];

I think I'll leave it out of the testcase, though, I'm not sure either whether or not it should be allowed.

[quickfur]

Rebased and updated with more tests.

[yebblies]

Needs the array tests too. And the test cases should all be crammed into xtest46 or one of the other existing megatests.

[PetarKirov]

@quickfur of course this:

const(A)[] concat1 = new const(A)[] ~ new immutable(C)[];

doesnt't work! I forgot to specifying the size :D

[9rnsr]

LGTM.

[9rnsr]

Auto-merge toggled on

[yebblies]

Auto-merge toggled off

[yebblies]

@9rnsr This still needs the test case from the forum added (array literal type deduction) and the test should be moved out of its own file.

[quickfur]

@yebblies Which forum thread was that? I must have missed it. Or are you referring to the array append test case posted above?

[quickfur]

Anyway, cooked up a few examples of my own. Would this do?

[yebblies]

I meant this thread

I think this is covered now.

[yebblies]

Auto-merge toggled on

[quickfur]

Thanks!