Rollup merge of #100984 - ChrisDenton:reinstate-init, r=Mark-Simulacrum

[rust.git] / compiler / rustc_mir_transform / src / const_prop_lint.rs

diff --git a/compiler/rustc_mir_transform/src/const_prop_lint.rs b/compiler/rustc_mir_transform/src/const_prop_lint.rs
index 74b146833d03f27ecdfe7778ff083cca442adccd..082d6c9f07e535c38175a741687ee8b144b85ea7 100644 (file)
--- a/compiler/rustc_mir_transform/src/const_prop_lint.rs
+++ b/compiler/rustc_mir_transform/src/const_prop_lint.rs
@@ -6,6 +6,7 @@
 use crate::const_prop::ConstPropMode;
 use crate::MirLint;
 use rustc_const_eval::const_eval::ConstEvalErr;
+use rustc_const_eval::interpret::Immediate;
 use rustc_const_eval::interpret::{
     self, InterpCx, InterpResult, LocalState, LocalValue, MemoryKind, OpTy, Scalar, StackPopCleanup,
 };
@@ -229,7 +230,13 @@ fn new(
 
     fn get_const(&self, place: Place<'tcx>) -> Option<OpTy<'tcx>> {
         let op = match self.ecx.eval_place_to_op(place, None) {
-            Ok(op) => op,
+            Ok(op) => {
+                if matches!(*op, interpret::Operand::Immediate(Immediate::Uninit)) {
+                    // Make sure nobody accidentally uses this value.
+                    return None;
+                }
+                op
+            }
             Err(e) => {
                 trace!("get_const failed: {}", e);
                 return None;
@@ -515,6 +522,14 @@ fn const_prop(
         if rvalue.needs_subst() {
             return None;
         }
+        if !rvalue
+            .ty(&self.ecx.frame().body.local_decls, *self.ecx.tcx)
+            .is_sized(self.ecx.tcx, self.param_env)
+        {
+            // the interpreter doesn't support unsized locals (only unsized arguments),
+            // but rustc does (in a kinda broken way), so we have to skip them here
+            return None;
+        }
 
         self.use_ecx(source_info, |this| this.ecx.eval_rvalue_into_place(rvalue, place))
     }
@@ -624,7 +639,11 @@ fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, location: Location
                 if let Some(ref value) = self.eval_operand(&cond, source_info) {
                     trace!("assertion on {:?} should be {:?}", value, expected);
                     let expected = Scalar::from_bool(*expected);
-                    let value_const = self.ecx.read_scalar(&value).unwrap();
+                    let Ok(value_const) = self.ecx.read_scalar(&value) else {
+                        // FIXME should be used use_ecx rather than a local match... but we have
+                        // quite a few of these read_scalar/read_immediate that need fixing.
+                        return
+                    };
                     if expected != value_const {
                         enum DbgVal<T> {
                             Val(T),
@@ -641,9 +660,9 @@ fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
                         let mut eval_to_int = |op| {
                             // This can be `None` if the lhs wasn't const propagated and we just
                             // triggered the assert on the value of the rhs.
-                            self.eval_operand(op, source_info).map_or(DbgVal::Underscore, |op| {
-                                DbgVal::Val(self.ecx.read_immediate(&op).unwrap().to_const_int())
-                            })
+                            self.eval_operand(op, source_info)
+                                .and_then(|op| self.ecx.read_immediate(&op).ok())
+                                .map_or(DbgVal::Underscore, |op| DbgVal::Val(op.to_const_int()))
                         };
                         let msg = match msg {
                             AssertKind::DivisionByZero(op) => {