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| author | Ralf Jung <post@ralfj.de> | 2022-08-06 17:18:59 -0400 |
|---|---|---|
| committer | Ralf Jung <post@ralfj.de> | 2022-08-06 18:31:59 -0400 |
| commit | 3c8563abcf91eda340aa77d238954dd00fa0cb34 (patch) | |
| tree | d7e3ee5ab863b63b9379a90e3542c4940a54cb47 /compiler | |
| parent | affe0d3a00e92fa7885e3f5d2c5073fde432d154 (diff) | |
| download | rust-3c8563abcf91eda340aa77d238954dd00fa0cb34.tar.gz rust-3c8563abcf91eda340aa77d238954dd00fa0cb34.zip | |
make NOP dyn casts not require anything about the vtable
Diffstat (limited to 'compiler')
| -rw-r--r-- | compiler/rustc_codegen_cranelift/src/unsize.rs | 1 | ||||
| -rw-r--r-- | compiler/rustc_codegen_ssa/src/base.rs | 1 | ||||
| -rw-r--r-- | compiler/rustc_const_eval/src/interpret/cast.rs | 7 |
3 files changed, 8 insertions, 1 deletions
diff --git a/compiler/rustc_codegen_cranelift/src/unsize.rs b/compiler/rustc_codegen_cranelift/src/unsize.rs index 052ca0a082b..dd9d891ddbd 100644 --- a/compiler/rustc_codegen_cranelift/src/unsize.rs +++ b/compiler/rustc_codegen_cranelift/src/unsize.rs @@ -29,6 +29,7 @@ pub(crate) fn unsized_info<'tcx>( let old_info = old_info.expect("unsized_info: missing old info for trait upcasting coercion"); if data_a.principal_def_id() == data_b.principal_def_id() { + // A NOP cast that doesn't actually change anything, should be allowed even with invalid vtables. return old_info; } diff --git a/compiler/rustc_codegen_ssa/src/base.rs b/compiler/rustc_codegen_ssa/src/base.rs index a840b270974..4c6be3f9108 100644 --- a/compiler/rustc_codegen_ssa/src/base.rs +++ b/compiler/rustc_codegen_ssa/src/base.rs @@ -151,6 +151,7 @@ pub fn unsized_info<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( let old_info = old_info.expect("unsized_info: missing old info for trait upcasting coercion"); if data_a.principal_def_id() == data_b.principal_def_id() { + // A NOP cast that doesn't actually change anything, should be allowed even with invalid vtables. return old_info; } diff --git a/compiler/rustc_const_eval/src/interpret/cast.rs b/compiler/rustc_const_eval/src/interpret/cast.rs index c97c31eb9da..14eb2a1537b 100644 --- a/compiler/rustc_const_eval/src/interpret/cast.rs +++ b/compiler/rustc_const_eval/src/interpret/cast.rs @@ -298,7 +298,12 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { self.write_immediate(val, dest) } (&ty::Dynamic(ref data_a, ..), &ty::Dynamic(ref data_b, ..)) => { - let (old_data, old_vptr) = self.read_immediate(src)?.to_scalar_pair()?; + let val = self.read_immediate(src)?; + if data_a.principal() == data_b.principal() { + // A NOP cast that doesn't actually change anything, should be allowed even with mismatching vtables. + return self.write_immediate(*val, dest); + } + let (old_data, old_vptr) = val.to_scalar_pair()?; let old_vptr = old_vptr.to_pointer(self)?; let (ty, old_trait) = self.get_ptr_vtable(old_vptr)?; if old_trait != data_a.principal() { |