linkonce-templates bugs about ldc HOT 2 OPEN

1.37.0-beta1

ldmd2 -betterC test1.d -I. -linkonce-templates 

test1.d

import test2;

@nogc nothrow:

enum ARR = idupArray!();

extern(C) int main(int argc, char** argv){
	return 0;
}

test2.d

module test2;

struct Column {
    @nogc nothrow:
	int id;
}

auto idupArray()(){
	if (!__ctfe)
			return null;
	Column[2] _arr;
	return _arr[0..1].idup;
}

import/core/internal/array/duplication.d(39): Error: appending to array in `res ~= cast(immutable(Column))e` requires the GC which is not available with -betterC

remove linkonce-templates fix the problem.

from ldc.

Thx for the nice test case. This ultimately boils down to __ctfe being a runtime-constant, so the .idup call still ends up being codegen'd at the IR level, and then drags in further templates, most notably

-linkonce-templates per definition emits all instantiated symbols referenced at the IR level, so a _dupCtfe instantiation too, which is only forward-declared without -linkonce-templates. In fact, without linker culling getting rid of unreferenced symbols:

ldc2 test1.d -betterC -disable-linker-strip-dead
ld: error: undefined symbol: _D4core8internal5array11duplication__T8_dupCtfeTS5test26ColumnTySQqQmZQBgFNaNbNiNfMAQBkZAyQBa
>>> referenced by test1.d
>>>               test1.o:(_D4core8internal5array11duplication__T4_dupTS5test26ColumnTySQqQmZQBcFNaNbNiNeMAQBkZAyQBa)
collect2: error: ld returned 1 exit status

from ldc.