Auto merge of #129970 - lukas-code:LayoutCalculator, r=compiler-errors

layout computation: gracefully handle unsized types in unexpected locations

This PR reworks the layout computation to eagerly return an error when encountering an unsized field where a sized field was expected, rather than delaying a bug and attempting to recover a layout. This is required, because with trivially false where clauses like `[T]: Sized`, any field can possible be an unsized type, without causing a compile error.

Since this PR removes the `delayed_bug` method from the `LayoutCalculator` trait, it essentially becomes the same as the `HasDataLayout` trait, so I've also refactored the `LayoutCalculator` to be a simple wrapper struct around a type that implements `HasDataLayout`.

The majority of the diff is whitespace changes, so viewing with whitespace ignored is advised.

implements rust-lang/rust#123169 (comment)

r? `@compiler-errors` or compiler

fixes rust-lang/rust#123134
fixes rust-lang/rust#124182
fixes rust-lang/rust#126939
fixes rust-lang/rust#127737

Author: bors

src/eval.rs

@@ -277,7 +277,7 @@ pub fn create_ecx<'tcx>(
     config: &MiriConfig,
 ) -> InterpResult<'tcx, InterpCx<'tcx, MiriMachine<'tcx>>> {
     let param_env = ty::ParamEnv::reveal_all();
-    let layout_cx = LayoutCx { tcx, param_env };
+    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));
 

src/machine.rs

@@ -21,7 +21,7 @@ use rustc_middle::{
     query::TyCtxtAt,
     ty::{
         self,
-        layout::{LayoutCx, LayoutError, LayoutOf, TyAndLayout},
+        layout::{HasTyCtxt, LayoutCx, LayoutError, LayoutOf, TyAndLayout},
         Instance, Ty, TyCtxt,
     },
 };
@@ -381,8 +381,8 @@ pub struct PrimitiveLayouts<'tcx> {
 }
 
 impl<'tcx> PrimitiveLayouts<'tcx> {
-    fn new(layout_cx: LayoutCx<'tcx, TyCtxt<'tcx>>) -> Result<Self, &'tcx LayoutError<'tcx>> {
-        let tcx = layout_cx.tcx;
+    fn new(layout_cx: LayoutCx<'tcx>) -> Result<Self, &'tcx LayoutError<'tcx>> {
+        let tcx = layout_cx.tcx();
         let mut_raw_ptr = Ty::new_mut_ptr(tcx, tcx.types.unit);
         let const_raw_ptr = Ty::new_imm_ptr(tcx, tcx.types.unit);
         Ok(Self {
@@ -596,14 +596,13 @@ pub struct MiriMachine<'tcx> {
 }
 
 impl<'tcx> MiriMachine<'tcx> {
-    pub(crate) fn new(config: &MiriConfig, layout_cx: LayoutCx<'tcx, TyCtxt<'tcx>>) -> Self {
-        let tcx = layout_cx.tcx;
+    pub(crate) fn new(config: &MiriConfig, layout_cx: LayoutCx<'tcx>) -> Self {
+        let tcx = layout_cx.tcx();
         let local_crates = helpers::get_local_crates(tcx);
         let layouts =
             PrimitiveLayouts::new(layout_cx).expect("Couldn't get layouts of primitive types");
         let profiler = config.measureme_out.as_ref().map(|out| {
-            let crate_name = layout_cx
-                .tcx
+            let crate_name = tcx
                 .sess
                 .opts
                 .crate_name
@@ -701,7 +700,7 @@ impl<'tcx> MiriMachine<'tcx> {
             clock: Clock::new(config.isolated_op == IsolatedOp::Allow),
             #[cfg(unix)]
             native_lib: config.native_lib.as_ref().map(|lib_file_path| {
-                let target_triple = layout_cx.tcx.sess.opts.target_triple.triple();
+                let target_triple = tcx.sess.opts.target_triple.triple();
                 // Check if host target == the session target.
                 if env!("TARGET") != target_triple {
                     panic!(