Out of bound idx for struct

[zjp-CN]

We got idx=2 for core::fmt::Arguments, but the struct only has two fields, and thus out of bounds:

                    if let Some(idx) = idx.as_field_idx()
                        && adt.def.kind().is_struct()
                    {
                        if let Some(field) = self.fields.get_mut(idx) {
                            field.read = v_fn.iter().map(|f| f.fn_def).collect();
                        } else {
                            panic!("adt={adt:#?} self={self:#?}")
                        }
                    }

thread 'rustc' (4100844) panicked at src/info_adt.rs:94:29:
adt=Adt {
    def: AdtDef(
        DefId {
            id: 22841,
            name: "fmt::Arguments",
        },
    ),
    args: GenericArgs(
        [
            Lifetime(
                Region {
                    kind: ReErased,
                },
            ),
        ],
    ),
    variant_fields: [
        VaraintField {
            idx: VariantIdx(None)-FieldIdx(Some(0)),
            name: "template",
        },
        VaraintField {
            idx: VariantIdx(None)-FieldIdx(Some(1)),
            name: "args",
        },
    ],
}

For simplicity, we choose to mute the case.

[zjp-CN]

Out of bounds: fields_len=2 idx=2 adt=Adt { def: AdtDef(DefId { id: 22841, name: "fmt::Arguments" }), args: GenericArgs([Lifetime(Region { kin
d: ReErased })]), variant_fields: [VaraintField { idx: VariantIdx(None)-FieldIdx(Some(0)), name: "template" }, VaraintField { idx: VariantIdx(
None)-FieldIdx(Some(1)), name: "args" }] }
Out of bounds: fields_len=2 idx=3 adt=Adt { def: AdtDef(DefId { id: 22841, name: "fmt::Arguments" }), args: GenericArgs([Lifetime(Region { kin
d: ReErased })]), variant_fields: [VaraintField { idx: VariantIdx(None)-FieldIdx(Some(0)), name: "template" }, VaraintField { idx: VariantIdx(
None)-FieldIdx(Some(1)), name: "args" }] }
Out of bounds: fields_len=2 idx=2 adt=Adt { def: AdtDef(DefId { id: 22926, name: "ops::range::Range" }), args: GenericArgs([Type(Ty { id: 47, 
kind: RigidTy(Uint(Usize)) })]), variant_fields: [VaraintField { idx: VariantIdx(None)-FieldIdx(Some(0)), name: "start" }, VaraintField { idx:
 VariantIdx(None)-FieldIdx(Some(1)), name: "end" }] }
Out of bounds: fields_len=2 idx=3 adt=Adt { def: AdtDef(DefId { id: 22926, name: "ops::range::Range" }), args: GenericArgs([Type(Ty { id: 47, 
kind: RigidTy(Uint(Usize)) })]), variant_fields: [VaraintField { idx: VariantIdx(None)-FieldIdx(Some(0)), name: "start" }, VaraintField { idx:
 VariantIdx(None)-FieldIdx(Some(1)), name: "end" }] }
Out of bounds: fields_len=2 idx=4 adt=Adt { def: AdtDef(DefId { id: 22926, name: "ops::range::Range" }), args: GenericArgs([Type(Ty { id: 47, 
kind: RigidTy(Uint(Usize)) })]), variant_fields: [VaraintField { idx: VariantIdx(None)-FieldIdx(Some(0)), name: "start" }, VaraintField { idx:
 VariantIdx(None)-FieldIdx(Some(1)), name: "end" }] }
Out of bounds: fields_len=1 idx=1 adt=Adt { def: AdtDef(DefId { id: 23322, name: "any::TypeId" }), args: GenericArgs([]), variant_fields: [Var
aintField { idx: VariantIdx(None)-FieldIdx(Some(0)), name: "data" }] }
Out of bounds: fields_len=1 idx=1 adt=Adt { def: AdtDef(DefId { id: 23194, name: "num::nonzero::NonZero" }), args: GenericArgs([Type(Ty { id: 
47, kind: RigidTy(Uint(Usize)) })]), variant_fields: [VaraintField { idx: VariantIdx(None)-FieldIdx(Some(0)), name: "0" }] }
Out of bounds: fields_len=0 idx=0 adt=Adt { def: AdtDef(DefId { id: 24434, name: "cell::BorrowError" }), args: GenericArgs([]), variant_fields
: [VaraintField { idx: VariantIdx(None)-FieldIdx(None), name: "" }] }
Out of bounds: fields_len=0 idx=0 adt=Adt { def: AdtDef(DefId { id: 24438, name: "cell::BorrowMutError" }), args: GenericArgs([]), variant_fie
lds: [VaraintField { idx: VariantIdx(None)-FieldIdx(None), name: "" }] }