Regression on main when allocating arrays of arrays

[LegNeato]

Minimal repro that fails to compile:

use spirv_std::spirv;

#[spirv(fragment)]
pub fn main() {
    let x = [[1; 2]; 1];
}

Bisects to 02cd324

It was found in #21 (comment) (assuming it is the same issue, but at least that is what I started with to get a repro)

[LegNeato]

@eddyb not sure if this will be fixed by your qptr stuff.

[eddyb]

Is this the error you're seeing?

error: cannot cast between pointer types
       from `*i32`
         to `*[i32; 2]`

With my various changes I also get:

error: error:0:0 - OpStore Pointer <id> '32[%32]' is not a logical pointer.
         OpStore %32 %33

And with a full move to qptr, something goes wrong with qptr.copy:

error: error:0:0 - Opcode CopyMemorySized requires one of these capabilities: Addresses 
         OpCopyMemorySized %29 %30 %uint_8

(and I'm not getting the kind of SPIR-T errors I would expect, either).

02cd324 shouldn't have broken anything like this, but that code is subtle and I am not exactly surprised.

My best guess is that something is being ambiguous about wanting access to the whole inner [_; 2] array, and instead it gets just the leaf field.

[LegNeato]

Yep, that's the error:

error: cannot cast between pointer types
       from `*i32`
         to `*[i32; 2]`

[LegNeato]

Also happens with arrays of vecs, which is more common: #189

[LegNeato]

Well, I am not smart enough / haven't cracked this yet. Spent a couple of hours on it.

Debug trace:

DEBUG rustc_codegen_spirv::builder::builder_methods recovering access chain: ty: Array { id: 17, element: Integer { id: 15, width: 32, signedness: true }, count: 2 }
 DEBUG rustc_codegen_spirv::builder::builder_methods recovering access chain: leaf_ty: None
 DEBUG rustc_codegen_spirv::builder::builder_methods NOT AN ADT
 DEBUG rustc_codegen_spirv::builder::builder_methods returning type: Integer { id: 15, width: 32, signedness: true }
 DEBUG rustc_codegen_spirv::builder::builder_methods maybe_original_access_chain
 DEBUG rustc_codegen_spirv::builder::builder_methods no original access chain
 DEBUG rustc_codegen_spirv::builder::builder_methods maybe_inbounds_gep calling pointercast
 DEBUG rustc_codegen_spirv::builder::builder_methods ptr.ty == dest_ty
 rustc_codegen_spirv::builder::builder_methods::emit_access_chain result_type=Pointer { id: 31, pointee: Integer { id: 15, width: 32, signedness: true } }
 rustc_codegen_spirv::builder::builder_methods::emit_access_chain result_type=Pointer { id: 31, pointee: Integer { id: 15, width: 32, signedness: true } }
 DEBUG rustc_codegen_spirv::builder::builder_methods recovering access chain: ty: Integer { id: 15, width: 32, signedness: true }
 DEBUG rustc_codegen_spirv::builder::builder_methods recovering access chain: leaf_ty: None
 DEBUG rustc_codegen_spirv::builder::builder_methods maybe_original_access_chain
 DEBUG rustc_codegen_spirv::builder::builder_methods has original access chain
 rustc_codegen_spirv::builder::builder_methods::emit_access_chain result_type=Pointer { id: 31, pointee: Integer { id: 15, width: 32, signedness: true } }
 rustc_codegen_spirv::builder::builder_methods::emit_access_chain result_type=Pointer { id: 31, pointee: Integer { id: 15, width: 32, signedness: true } }
 DEBUG rustc_codegen_spirv::builder::builder_methods adjust_pointer_for_typed_access
 DEBUG rustc_codegen_spirv::builder::builder_methods before adjust_pointer_for_sized_access i32
 DEBUG rustc_codegen_spirv::builder::builder_methods recovering access chain: ty: Integer { id: 15, width: 32, signedness: true }
 DEBUG rustc_codegen_spirv::builder::builder_methods recovering access chain: leaf_ty: None
 DEBUG rustc_codegen_spirv::builder::builder_methods after adjust_pointer_for_sized_access i32
 DEBUG rustc_codegen_spirv::builder::builder_methods adjust_pointer_for_sized_access returning *i32 i32
 DEBUG rustc_codegen_spirv::builder::builder_methods val: i32 -> dest: i32
 DEBUG rustc_codegen_spirv::builder::builder_methods recovering access chain: ty: Integer { id: 15, width: 32, signedness: true }
 DEBUG rustc_codegen_spirv::builder::builder_methods recovering access chain: leaf_ty: None
 DEBUG rustc_codegen_spirv::builder::builder_methods maybe_original_access_chain
 DEBUG rustc_codegen_spirv::builder::builder_methods has original access chain
 rustc_codegen_spirv::builder::builder_methods::emit_access_chain result_type=Pointer { id: 31, pointee: Integer { id: 15, width: 32, signedness: true } }
 rustc_codegen_spirv::builder::builder_methods::emit_access_chain result_type=Pointer { id: 31, pointee: Integer { id: 15, width: 32, signedness: true } }
 DEBUG rustc_codegen_spirv::builder::builder_methods adjust_pointer_for_typed_access
 DEBUG rustc_codegen_spirv::builder::builder_methods before adjust_pointer_for_sized_access i32
 DEBUG rustc_codegen_spirv::builder::builder_methods recovering access chain: ty: Integer { id: 15, width: 32, signedness: true }
 DEBUG rustc_codegen_spirv::builder::builder_methods recovering access chain: leaf_ty: None
 DEBUG rustc_codegen_spirv::builder::builder_methods after adjust_pointer_for_sized_access i32
 DEBUG rustc_codegen_spirv::builder::builder_methods adjust_pointer_for_sized_access returning *i32 i32
 DEBUG rustc_codegen_spirv::builder::builder_methods val: i32 -> dest: i32
 DEBUG rustc_codegen_spirv::builder::builder_methods recovering access chain: ty: Array { id: 19, element: Array { id: 17, element: Integer { id: 15, width: 32, signedness: true }, count: 2 }, count: 1 }
 DEBUG rustc_codegen_spirv::builder::builder_methods recovering access chain: leaf_ty: None
 DEBUG rustc_codegen_spirv::builder::builder_methods NOT AN ADT
 DEBUG rustc_codegen_spirv::builder::builder_methods returning type: Array { id: 17, element: Integer { id: 15, width: 32, signedness: true }, count: 2 }
 DEBUG rustc_codegen_spirv::builder::builder_methods maybe_original_access_chain
 DEBUG rustc_codegen_spirv::builder::builder_methods no original access chain
 DEBUG rustc_codegen_spirv::builder::builder_methods maybe_inbounds_gep calling pointercast
 DEBUG rustc_codegen_spirv::builder::builder_methods ptr.ty == dest_ty
 rustc_codegen_spirv::builder::builder_methods::emit_access_chain result_type=Pointer { id: 22, pointee: Array { id: 17, element: Integer { id: 15, width: 32, signedness: true }, count: 2 } }
 rustc_codegen_spirv::builder::builder_methods::emit_access_chain result_type=Pointer { id: 22, pointee: Array { id: 17, element: Integer { id: 15, width: 32, signedness: true }, count: 2 } }
 DEBUG rustc_codegen_spirv::builder::builder_methods recovering access chain: ty: Array { id: 17, element: Integer { id: 15, width: 32, signedness: true }, count: 2 }
 DEBUG rustc_codegen_spirv::builder::builder_methods recovering access chain: leaf_ty: None
 DEBUG rustc_codegen_spirv::builder::builder_methods NOT AN ADT
 DEBUG rustc_codegen_spirv::builder::builder_methods returning type: Integer { id: 15, width: 32, signedness: true }
 DEBUG rustc_codegen_spirv::builder::builder_methods RESULT base_pointee: i32
 DEBUG rustc_codegen_spirv::builder::builder_methods RESULT result_pointee: [i32; 2]
 rustc_codegen_spirv::builder::builder_methods::emit_access_chain result_type=Pointer { id: 31, pointee: Integer { id: 15, width: 32, signedness: true } }
 rustc_codegen_spirv::builder::builder_methods::emit_access_chain result_type=Pointer { id: 31, pointee: Integer { id: 15, width: 32, signedness: true } }
 DEBUG rustc_codegen_spirv::builder::builder_methods adjusting_pointers: *[i32; 2] -> *i32
 DEBUG rustc_codegen_spirv::builder::builder_methods before adjust_pointer_for_sized_access i32
 DEBUG rustc_codegen_spirv::builder::builder_methods recovering access chain: ty: Integer { id: 15, width: 32, signedness: true }
 DEBUG rustc_codegen_spirv::builder::builder_methods recovering access chain: leaf_ty: None
 DEBUG rustc_codegen_spirv::builder::builder_methods after adjust_pointer_for_sized_access i32
 DEBUG rustc_codegen_spirv::builder::builder_methods before adjust_pointer_for_sized_access [i32; 2]
 DEBUG rustc_codegen_spirv::builder::builder_methods recovering access chain: ty: Array { id: 17, element: Integer { id: 15, width: 32, signedness: true }, count: 2 }
 DEBUG rustc_codegen_spirv::builder::builder_methods recovering access chain: leaf_ty: None
 DEBUG rustc_codegen_spirv::builder::builder_methods NOT AN ADT
 DEBUG rustc_codegen_spirv::builder::builder_methods avoiding digging beyond the point the leaf could actually fit
 DEBUG rustc_codegen_spirv::builder::builder_methods after adjust_pointer_for_sized_access [i32; 2]
 DEBUG rustc_codegen_spirv::builder::builder_methods adjust_pointer_for_sized_access returning *[i32; 2] [i32; 2]
 DEBUG rustc_codegen_spirv::builder::builder_methods src adjusted memcpy calling pointercast: *i32 -> [i32; 2], src: *[i32; 2]
 DEBUG rustc_codegen_spirv::builder::builder_methods ptr type after strippint pointer cases: *i32
 DEBUG rustc_codegen_spirv::builder::builder_methods recovering access chain: ty: Integer { id: 15, width: 32, signedness: true }
 DEBUG rustc_codegen_spirv::builder::builder_methods recovering access chain: leaf_ty: Array { id: 17, element: Integer { id: 15, width: 32, signedness: true }, count: 2 }
 DEBUG rustc_codegen_spirv::builder::builder_methods ptr.type: *i32 dest_ty: *[i32; 2]
 DEBUG rustc_codegen_spirv::builder::builder_methods copying memory