use TypingEnv when no infcx is available

the behavior of the type system not only depends on the current
assumptions, but also the currentnphase of the compiler. This is
mostly necessary as we need to decide whether and how to reveal
opaque types. We track this via the `TypingMode`.

Author: lcnr

src/borrow_tracker/stacked_borrows/mod.rs

@@ -12,7 +12,7 @@ use std::{cmp, mem};
 use rustc_abi::{BackendRepr, Size};
 use rustc_data_structures::fx::FxHashSet;
 use rustc_middle::mir::{Mutability, RetagKind};
-use rustc_middle::ty::layout::HasParamEnv;
+use rustc_middle::ty::layout::HasTypingEnv;
 use rustc_middle::ty::{self, Ty};
 
 use self::diagnostics::{RetagCause, RetagInfo};

src/borrow_tracker/tree_borrows/mod.rs

@@ -1,6 +1,6 @@
 use rustc_abi::{BackendRepr, Size};
 use rustc_middle::mir::{Mutability, RetagKind};
-use rustc_middle::ty::layout::HasParamEnv;
+use rustc_middle::ty::layout::HasTypingEnv;
 use rustc_middle::ty::{self, Ty};
 use rustc_span::def_id::DefId;
 

src/eval.rs

@@ -268,10 +268,14 @@ pub fn create_ecx<'tcx>(
     entry_type: EntryFnType,
     config: &MiriConfig,
 ) -> InterpResult<'tcx, InterpCx<'tcx, MiriMachine<'tcx>>> {
-    let param_env = ty::ParamEnv::reveal_all();
-    let layout_cx = LayoutCx::new(tcx, param_env);
-    let mut ecx =
-        InterpCx::new(tcx, rustc_span::DUMMY_SP, param_env, MiriMachine::new(config, layout_cx));
+    let typing_env = ty::TypingEnv::fully_monomorphized();
+    let layout_cx = LayoutCx::new(tcx, typing_env);
+    let mut ecx = InterpCx::new(
+        tcx,
+        rustc_span::DUMMY_SP,
+        typing_env.param_env,
+        MiriMachine::new(config, layout_cx)
+    );
 
     // Some parts of initialization require a full `InterpCx`.
     MiriMachine::late_init(&mut ecx, config, {
@@ -376,7 +380,7 @@ pub fn create_ecx<'tcx>(
             let main_ret_ty = main_ret_ty.no_bound_vars().unwrap();
             let start_instance = ty::Instance::try_resolve(
                 tcx,
-                ty::ParamEnv::reveal_all(),
+                typing_env,
                 start_id,
                 tcx.mk_args(&[ty::GenericArg::from(main_ret_ty)]),
             )

src/helpers.rs

@@ -116,8 +116,8 @@ pub fn resolve_path<'tcx>(
 /// Gets the layout of a type at a path.
 #[track_caller]
 pub fn path_ty_layout<'tcx>(cx: &impl LayoutOf<'tcx>, path: &[&str]) -> TyAndLayout<'tcx> {
-    let ty =
-        resolve_path(cx.tcx(), path, Namespace::TypeNS).ty(cx.tcx(), ty::ParamEnv::reveal_all());
+    let ty = resolve_path(cx.tcx(), path, Namespace::TypeNS)
+        .ty(cx.tcx(), cx.typing_env());
     cx.layout_of(ty).to_result().ok().unwrap()
 }
 

src/machine.rs

@@ -1127,7 +1127,9 @@ impl<'tcx> Machine<'tcx> for MiriMachine<'tcx> {
             };
             let info = ecx.get_alloc_info(alloc_id);
             let def_ty = ecx.tcx.type_of(def_id).instantiate_identity();
-            let extern_decl_layout = ecx.tcx.layout_of(ty::ParamEnv::empty().and(def_ty)).unwrap();
+            let extern_decl_layout = ecx.tcx.layout_of(
+                ecx.typing_env().as_query_input(def_ty)
+            ).unwrap();
             if extern_decl_layout.size != info.size || extern_decl_layout.align.abi != info.align {
                 throw_unsup_format!(
                     "extern static `{link_name}` has been declared as `{krate}::{name}` \