Rollup merge of #88709 - BoxyUwU:thir-abstract-const, r=lcnr

generic_const_exprs: use thir for abstract consts instead of mir

Changes `AbstractConst` building to use `thir` instead of `mir` so that there's less chance of consts unifying when they shouldn't because lowering to mir dropped information (see `abstract-consts-as-cast-5.rs` test)

r? `@lcnr`

4 files changed, 5 insertions, 244 deletions

diff --git a/compiler/rustc_mir_build/src/build/mod.rs b/compiler/rustc_mir_build/src/build/mod.rs
index 0a760a740dc..0ee740a6463 100644
--- a/compiler/rustc_mir_build/src/build/mod.rs
+++ b/compiler/rustc_mir_build/src/build/mod.rs
@@ -47,10 +47,12 @@ fn mir_build(tcx: TyCtxt<'_>, def: ty::WithOptConstParam<LocalDefId>) -> Body<'_
     // Ensure unsafeck is ran before we steal the THIR.
     match def {
         ty::WithOptConstParam { did, const_param_did: Some(const_param_did) } => {
-            tcx.ensure().thir_check_unsafety_for_const_arg((did, const_param_did))
+            tcx.ensure().thir_check_unsafety_for_const_arg((did, const_param_did));
+            tcx.ensure().thir_abstract_const_of_const_arg((did, const_param_did));
         }
         ty::WithOptConstParam { did, const_param_did: None } => {
-            tcx.ensure().thir_check_unsafety(did)
+            tcx.ensure().thir_check_unsafety(did);
+            tcx.ensure().thir_abstract_const(did);
         }
     }
 
diff --git a/compiler/rustc_mir_build/src/check_unsafety.rs b/compiler/rustc_mir_build/src/check_unsafety.rs
index 05a5fcef16a..0e82b187201 100644
--- a/compiler/rustc_mir_build/src/check_unsafety.rs
+++ b/compiler/rustc_mir_build/src/check_unsafety.rs
@@ -1,5 +1,5 @@
 use crate::build::ExprCategory;
-use crate::thir::visit::{self, Visitor};
+use rustc_middle::thir::visit::{self, Visitor};
 
 use rustc_errors::struct_span_err;
 use rustc_hir as hir;
diff --git a/compiler/rustc_mir_build/src/thir/mod.rs b/compiler/rustc_mir_build/src/thir/mod.rs
index e5123d8ef0c..ddbe1b0b69c 100644
--- a/compiler/rustc_mir_build/src/thir/mod.rs
+++ b/compiler/rustc_mir_build/src/thir/mod.rs
@@ -11,4 +11,3 @@ crate mod cx;
 crate mod pattern;
 
 mod util;
-pub mod visit;
diff --git a/compiler/rustc_mir_build/src/thir/visit.rs b/compiler/rustc_mir_build/src/thir/visit.rs
deleted file mode 100644
index 51c371b8720..00000000000
--- a/compiler/rustc_mir_build/src/thir/visit.rs
+++ /dev/null
@@ -1,240 +0,0 @@
-use rustc_middle::thir::{self, *};
-use rustc_middle::ty::Const;
-
-pub trait Visitor<'a, 'tcx: 'a>: Sized {
-    fn thir(&self) -> &'a Thir<'tcx>;
-
-    fn visit_expr(&mut self, expr: &Expr<'tcx>) {
-        walk_expr(self, expr);
-    }
-
-    fn visit_stmt(&mut self, stmt: &Stmt<'tcx>) {
-        walk_stmt(self, stmt);
-    }
-
-    fn visit_block(&mut self, block: &Block) {
-        walk_block(self, block);
-    }
-
-    fn visit_arm(&mut self, arm: &Arm<'tcx>) {
-        walk_arm(self, arm);
-    }
-
-    fn visit_pat(&mut self, pat: &Pat<'tcx>) {
-        walk_pat(self, pat);
-    }
-
-    fn visit_const(&mut self, _cnst: &'tcx Const<'tcx>) {}
-}
-
-pub fn walk_expr<'a, 'tcx: 'a, V: Visitor<'a, 'tcx>>(visitor: &mut V, expr: &Expr<'tcx>) {
-    use ExprKind::*;
-    match expr.kind {
-        Scope { value, region_scope: _, lint_level: _ } => {
-            visitor.visit_expr(&visitor.thir()[value])
-        }
-        Box { value } => visitor.visit_expr(&visitor.thir()[value]),
-        If { cond, then, else_opt, if_then_scope: _ } => {
-            visitor.visit_expr(&visitor.thir()[cond]);
-            visitor.visit_expr(&visitor.thir()[then]);
-            if let Some(else_expr) = else_opt {
-                visitor.visit_expr(&visitor.thir()[else_expr]);
-            }
-        }
-        Call { fun, ref args, ty: _, from_hir_call: _, fn_span: _ } => {
-            visitor.visit_expr(&visitor.thir()[fun]);
-            for &arg in &**args {
-                visitor.visit_expr(&visitor.thir()[arg]);
-            }
-        }
-        Deref { arg } => visitor.visit_expr(&visitor.thir()[arg]),
-        Binary { lhs, rhs, op: _ } | LogicalOp { lhs, rhs, op: _ } => {
-            visitor.visit_expr(&visitor.thir()[lhs]);
-            visitor.visit_expr(&visitor.thir()[rhs]);
-        }
-        Unary { arg, op: _ } => visitor.visit_expr(&visitor.thir()[arg]),
-        Cast { source } => visitor.visit_expr(&visitor.thir()[source]),
-        Use { source } => visitor.visit_expr(&visitor.thir()[source]),
-        NeverToAny { source } => visitor.visit_expr(&visitor.thir()[source]),
-        Pointer { source, cast: _ } => visitor.visit_expr(&visitor.thir()[source]),
-        Let { expr, .. } => {
-            visitor.visit_expr(&visitor.thir()[expr]);
-        }
-        Loop { body } => visitor.visit_expr(&visitor.thir()[body]),
-        Match { scrutinee, ref arms } => {
-            visitor.visit_expr(&visitor.thir()[scrutinee]);
-            for &arm in &**arms {
-                visitor.visit_arm(&visitor.thir()[arm]);
-            }
-        }
-        Block { ref body } => visitor.visit_block(body),
-        Assign { lhs, rhs } | AssignOp { lhs, rhs, op: _ } => {
-            visitor.visit_expr(&visitor.thir()[lhs]);
-            visitor.visit_expr(&visitor.thir()[rhs]);
-        }
-        Field { lhs, name: _ } => visitor.visit_expr(&visitor.thir()[lhs]),
-        Index { lhs, index } => {
-            visitor.visit_expr(&visitor.thir()[lhs]);
-            visitor.visit_expr(&visitor.thir()[index]);
-        }
-        VarRef { id: _ } | UpvarRef { closure_def_id: _, var_hir_id: _ } => {}
-        Borrow { arg, borrow_kind: _ } => visitor.visit_expr(&visitor.thir()[arg]),
-        AddressOf { arg, mutability: _ } => visitor.visit_expr(&visitor.thir()[arg]),
-        Break { value, label: _ } => {
-            if let Some(value) = value {
-                visitor.visit_expr(&visitor.thir()[value])
-            }
-        }
-        Continue { label: _ } => {}
-        Return { value } => {
-            if let Some(value) = value {
-                visitor.visit_expr(&visitor.thir()[value])
-            }
-        }
-        ConstBlock { value } => visitor.visit_const(value),
-        Repeat { value, count } => {
-            visitor.visit_expr(&visitor.thir()[value]);
-            visitor.visit_const(count);
-        }
-        Array { ref fields } | Tuple { ref fields } => {
-            for &field in &**fields {
-                visitor.visit_expr(&visitor.thir()[field]);
-            }
-        }
-        Adt(box thir::Adt {
-            ref fields,
-            ref base,
-            adt_def: _,
-            variant_index: _,
-            substs: _,
-            user_ty: _,
-        }) => {
-            for field in &**fields {
-                visitor.visit_expr(&visitor.thir()[field.expr]);
-            }
-            if let Some(base) = base {
-                visitor.visit_expr(&visitor.thir()[base.base]);
-            }
-        }
-        PlaceTypeAscription { source, user_ty: _ } | ValueTypeAscription { source, user_ty: _ } => {
-            visitor.visit_expr(&visitor.thir()[source])
-        }
-        Closure { closure_id: _, substs: _, upvars: _, movability: _, fake_reads: _ } => {}
-        Literal { literal, user_ty: _, const_id: _ } => visitor.visit_const(literal),
-        StaticRef { literal, def_id: _ } => visitor.visit_const(literal),
-        InlineAsm { ref operands, template: _, options: _, line_spans: _ } => {
-            for op in &**operands {
-                use InlineAsmOperand::*;
-                match op {
-                    In { expr, reg: _ }
-                    | Out { expr: Some(expr), reg: _, late: _ }
-                    | InOut { expr, reg: _, late: _ }
-                    | SymFn { expr } => visitor.visit_expr(&visitor.thir()[*expr]),
-                    SplitInOut { in_expr, out_expr, reg: _, late: _ } => {
-                        visitor.visit_expr(&visitor.thir()[*in_expr]);
-                        if let Some(out_expr) = out_expr {
-                            visitor.visit_expr(&visitor.thir()[*out_expr]);
-                        }
-                    }
-                    Out { expr: None, reg: _, late: _ }
-                    | Const { value: _, span: _ }
-                    | SymStatic { def_id: _ } => {}
-                }
-            }
-        }
-        ThreadLocalRef(_) => {}
-        LlvmInlineAsm { ref outputs, ref inputs, asm: _ } => {
-            for &out_expr in &**outputs {
-                visitor.visit_expr(&visitor.thir()[out_expr]);
-            }
-            for &in_expr in &**inputs {
-                visitor.visit_expr(&visitor.thir()[in_expr]);
-            }
-        }
-        Yield { value } => visitor.visit_expr(&visitor.thir()[value]),
-    }
-}
-
-pub fn walk_stmt<'a, 'tcx: 'a, V: Visitor<'a, 'tcx>>(visitor: &mut V, stmt: &Stmt<'tcx>) {
-    match &stmt.kind {
-        StmtKind::Expr { expr, scope: _ } => visitor.visit_expr(&visitor.thir()[*expr]),
-        StmtKind::Let {
-            initializer,
-            remainder_scope: _,
-            init_scope: _,
-            ref pattern,
-            lint_level: _,
-        } => {
-            if let Some(init) = initializer {
-                visitor.visit_expr(&visitor.thir()[*init]);
-            }
-            visitor.visit_pat(pattern);
-        }
-    }
-}
-
-pub fn walk_block<'a, 'tcx: 'a, V: Visitor<'a, 'tcx>>(visitor: &mut V, block: &Block) {
-    for &stmt in &*block.stmts {
-        visitor.visit_stmt(&visitor.thir()[stmt]);
-    }
-    if let Some(expr) = block.expr {
-        visitor.visit_expr(&visitor.thir()[expr]);
-    }
-}
-
-pub fn walk_arm<'a, 'tcx: 'a, V: Visitor<'a, 'tcx>>(visitor: &mut V, arm: &Arm<'tcx>) {
-    match arm.guard {
-        Some(Guard::If(expr)) => visitor.visit_expr(&visitor.thir()[expr]),
-        Some(Guard::IfLet(ref pat, expr)) => {
-            visitor.visit_pat(pat);
-            visitor.visit_expr(&visitor.thir()[expr]);
-        }
-        None => {}
-    }
-    visitor.visit_pat(&arm.pattern);
-    visitor.visit_expr(&visitor.thir()[arm.body]);
-}
-
-pub fn walk_pat<'a, 'tcx: 'a, V: Visitor<'a, 'tcx>>(visitor: &mut V, pat: &Pat<'tcx>) {
-    use PatKind::*;
-    match pat.kind.as_ref() {
-        AscribeUserType { subpattern, ascription: _ }
-        | Deref { subpattern }
-        | Binding {
-            subpattern: Some(subpattern),
-            mutability: _,
-            mode: _,
-            var: _,
-            ty: _,
-            is_primary: _,
-            name: _,
-        } => visitor.visit_pat(&subpattern),
-        Binding { .. } | Wild => {}
-        Variant { subpatterns, adt_def: _, substs: _, variant_index: _ } | Leaf { subpatterns } => {
-            for subpattern in subpatterns {
-                visitor.visit_pat(&subpattern.pattern);
-            }
-        }
-        Constant { value } => visitor.visit_const(value),
-        Range(range) => {
-            visitor.visit_const(range.lo);
-            visitor.visit_const(range.hi);
-        }
-        Slice { prefix, slice, suffix } | Array { prefix, slice, suffix } => {
-            for subpattern in prefix {
-                visitor.visit_pat(&subpattern);
-            }
-            if let Some(pat) = slice {
-                visitor.visit_pat(pat);
-            }
-            for subpattern in suffix {
-                visitor.visit_pat(&subpattern);
-            }
-        }
-        Or { pats } => {
-            for pat in pats {
-                visitor.visit_pat(&pat);
-            }
-        }
-    };
-}