fix ICE when promoted has layout size overflow

Author: RalfJung

compiler/rustc_const_eval/src/const_eval/error.rs

@@ -139,29 +139,36 @@ where
     match error {
         // Don't emit a new diagnostic for these errors, they are already reported elsewhere or
         // should remain silent.
+        err_inval!(AlreadyReported(info)) => ErrorHandled::Reported(info, span),
         err_inval!(Layout(LayoutError::Unknown(_))) | err_inval!(TooGeneric) => {
             ErrorHandled::TooGeneric(span)
         }
-        err_inval!(AlreadyReported(guar)) => ErrorHandled::Reported(guar, span),
         err_inval!(Layout(LayoutError::ReferencesError(guar))) => {
-            ErrorHandled::Reported(ReportedErrorInfo::tainted_by_errors(guar), span)
+            // This can occur in infallible promoteds e.g. when a non-existent type or field is
+            // encountered.
+            ErrorHandled::Reported(ReportedErrorInfo::allowed_in_infallible(guar), span)
         }
         // Report remaining errors.
         _ => {
             let (our_span, frames) = get_span_and_frames();
             let span = span.substitute_dummy(our_span);
             let err = mk(span, frames);
             let mut err = tcx.dcx().create_err(err);
-            let can_be_spurious = matches!(error, InterpErrorKind::ResourceExhaustion(_));
+            // We allow invalid programs in infallible promoteds since invalid layouts can occur
+            // anyway (e.g. due to size overflow). And we allow OOM as that can happy any time.
+            let allowed_in_infallible = matches!(
+                error,
+                InterpErrorKind::ResourceExhaustion(_) | InterpErrorKind::InvalidProgram(_)
+            );
 
             let msg = error.diagnostic_message();
             error.add_args(&mut err);
 
             // Use *our* span to label the interp error
             err.span_label(our_span, msg);
             let g = err.emit();
-            let reported = if can_be_spurious {
-                ReportedErrorInfo::spurious(g)
+            let reported = if allowed_in_infallible {
+                ReportedErrorInfo::allowed_in_infallible(g)
             } else {
                 ReportedErrorInfo::from(g)
             };

compiler/rustc_const_eval/src/interpret/eval_context.rs

@@ -268,7 +268,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         };
         // do not continue if typeck errors occurred (can only occur in local crate)
         if let Some(err) = body.tainted_by_errors {
-            throw_inval!(AlreadyReported(ReportedErrorInfo::tainted_by_errors(err)));
+            throw_inval!(AlreadyReported(ReportedErrorInfo::from(err)));
         }
         interp_ok(body)
     }
@@ -585,13 +585,10 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                     match err {
                         ErrorHandled::TooGeneric(..) => {},
                         ErrorHandled::Reported(reported, span) => {
-                            if reported.is_tainted_by_errors() {
-                                // const-eval will return "tainted" errors if e.g. the layout cannot
-                                // be computed as the type references non-existing names.
-                                // See <https://github.com/rust-lang/rust/issues/124348>.
-                            } else if reported.can_be_spurious() {
+                            if reported.is_allowed_in_infallible() {
                                 // These errors can just sometimes happen, even when the expression
-                                // is nominally "infallible", e.g. when running out of memory.
+                                // is nominally "infallible", e.g. when running out of memory
+                                // or when some layout could not be computed.
                             } else {
                                 // Looks like the const is not captured by `required_consts`, that's bad.
                                 span_bug!(span, "interpret const eval failure of {val:?} which is not in required_consts");

compiler/rustc_middle/src/mir/interpret/error.rs

@@ -46,7 +46,7 @@ impl ErrorHandled {
     pub fn emit_note(&self, tcx: TyCtxt<'_>) {
         match self {
             &ErrorHandled::Reported(err, span) => {
-                if !err.is_tainted_by_errors && !span.is_dummy() {
+                if !err.allowed_in_infallible && !span.is_dummy() {
                     tcx.dcx().emit_note(error::ErroneousConstant { span });
                 }
             }
@@ -58,34 +58,26 @@ impl ErrorHandled {
 #[derive(Debug, Copy, Clone, PartialEq, Eq, HashStable, TyEncodable, TyDecodable)]
 pub struct ReportedErrorInfo {
     error: ErrorGuaranteed,
-    is_tainted_by_errors: bool,
-    /// Whether this is the kind of error that can sometimes occur, and sometimes not.
-    /// Used for resource exhaustion errors.
-    can_be_spurious: bool,
+    /// Whether this error is allowed to show up even in otherwise "infallible" promoteds.
+    /// This is for things like overflows during size computation or resource exhaustion.
+    allowed_in_infallible: bool,
 }
 
 impl ReportedErrorInfo {
     #[inline]
-    pub fn tainted_by_errors(error: ErrorGuaranteed) -> ReportedErrorInfo {
-        ReportedErrorInfo { is_tainted_by_errors: true, can_be_spurious: false, error }
-    }
-    #[inline]
-    pub fn spurious(error: ErrorGuaranteed) -> ReportedErrorInfo {
-        ReportedErrorInfo { can_be_spurious: true, is_tainted_by_errors: false, error }
+    pub fn allowed_in_infallible(error: ErrorGuaranteed) -> ReportedErrorInfo {
+        ReportedErrorInfo { allowed_in_infallible: true, error }
     }
 
-    pub fn is_tainted_by_errors(&self) -> bool {
-        self.is_tainted_by_errors
-    }
-    pub fn can_be_spurious(&self) -> bool {
-        self.can_be_spurious
+    pub fn is_allowed_in_infallible(&self) -> bool {
+        self.allowed_in_infallible
     }
 }
 
 impl From<ErrorGuaranteed> for ReportedErrorInfo {
     #[inline]
     fn from(error: ErrorGuaranteed) -> ReportedErrorInfo {
-        ReportedErrorInfo { is_tainted_by_errors: false, can_be_spurious: false, error }
+        ReportedErrorInfo { allowed_in_infallible: false, error }
     }
 }
 

tests/crashes/125476.rs

@@ -72,6 +72,20 @@ help: add `#![feature(adt_const_params)]` to the crate attributes to enable more
 LL + #![feature(adt_const_params)]
    |
 
+note: erroneous constant encountered
+  --> $DIR/unevaluated-const-ice-119731.rs:22:19
+   |
+LL |     impl v17<512, v0> {
+   |                   ^^
+
+note: erroneous constant encountered
+  --> $DIR/unevaluated-const-ice-119731.rs:22:19
+   |
+LL |     impl v17<512, v0> {
+   |                   ^^
+   |
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
 error: maximum number of nodes exceeded in constant v20::v17::<v10, v2>::{constant#0}
   --> $DIR/unevaluated-const-ice-119731.rs:28:37
    |

tests/ui/const-generics/generic_const_exprs/unevaluated-const-ice-119731.stderr

@@ -16,6 +16,12 @@ error[E0308]: mismatched types
 LL | const X: usize = 42 && 39;
    |                  ^^^^^^^^ expected `usize`, found `bool`
 
+note: erroneous constant encountered
+  --> $DIR/const-integer-bool-ops.rs:8:18
+   |
+LL | const ARR: [i32; X] = [99; 34];
+   |                  ^
+
 error[E0308]: mismatched types
   --> $DIR/const-integer-bool-ops.rs:10:19
    |
@@ -34,6 +40,12 @@ error[E0308]: mismatched types
 LL | const X1: usize = 42 || 39;
    |                   ^^^^^^^^ expected `usize`, found `bool`
 
+note: erroneous constant encountered
+  --> $DIR/const-integer-bool-ops.rs:17:19
+   |
+LL | const ARR1: [i32; X1] = [99; 47];
+   |                   ^^
+
 error[E0308]: mismatched types
   --> $DIR/const-integer-bool-ops.rs:19:19
    |
@@ -52,6 +64,12 @@ error[E0308]: mismatched types
 LL | const X2: usize = -42 || -39;
    |                   ^^^^^^^^^^ expected `usize`, found `bool`
 
+note: erroneous constant encountered
+  --> $DIR/const-integer-bool-ops.rs:26:19
+   |
+LL | const ARR2: [i32; X2] = [99; 18446744073709551607];
+   |                   ^^
+
 error[E0308]: mismatched types
   --> $DIR/const-integer-bool-ops.rs:28:19
    |
@@ -70,42 +88,84 @@ error[E0308]: mismatched types
 LL | const X3: usize = -42 && -39;
    |                   ^^^^^^^^^^ expected `usize`, found `bool`
 
+note: erroneous constant encountered
+  --> $DIR/const-integer-bool-ops.rs:35:19
+   |
+LL | const ARR3: [i32; X3] = [99; 6];
+   |                   ^^
+
 error[E0308]: mismatched types
   --> $DIR/const-integer-bool-ops.rs:37:18
    |
 LL | const Y: usize = 42.0 == 42.0;
    |                  ^^^^^^^^^^^^ expected `usize`, found `bool`
 
+note: erroneous constant encountered
+  --> $DIR/const-integer-bool-ops.rs:40:19
+   |
+LL | const ARRR: [i32; Y] = [99; 1];
+   |                   ^
+
 error[E0308]: mismatched types
   --> $DIR/const-integer-bool-ops.rs:42:19
    |
 LL | const Y1: usize = 42.0 >= 42.0;
    |                   ^^^^^^^^^^^^ expected `usize`, found `bool`
 
+note: erroneous constant encountered
+  --> $DIR/const-integer-bool-ops.rs:45:20
+   |
+LL | const ARRR1: [i32; Y1] = [99; 1];
+   |                    ^^
+
 error[E0308]: mismatched types
   --> $DIR/const-integer-bool-ops.rs:47:19
    |
 LL | const Y2: usize = 42.0 <= 42.0;
    |                   ^^^^^^^^^^^^ expected `usize`, found `bool`
 
+note: erroneous constant encountered
+  --> $DIR/const-integer-bool-ops.rs:50:20
+   |
+LL | const ARRR2: [i32; Y2] = [99; 1];
+   |                    ^^
+
 error[E0308]: mismatched types
   --> $DIR/const-integer-bool-ops.rs:52:19
    |
 LL | const Y3: usize = 42.0 > 42.0;
    |                   ^^^^^^^^^^^ expected `usize`, found `bool`
 
+note: erroneous constant encountered
+  --> $DIR/const-integer-bool-ops.rs:55:20
+   |
+LL | const ARRR3: [i32; Y3] = [99; 0];
+   |                    ^^
+
 error[E0308]: mismatched types
   --> $DIR/const-integer-bool-ops.rs:57:19
    |
 LL | const Y4: usize = 42.0 < 42.0;
    |                   ^^^^^^^^^^^ expected `usize`, found `bool`
 
+note: erroneous constant encountered
+  --> $DIR/const-integer-bool-ops.rs:60:20
+   |
+LL | const ARRR4: [i32; Y4] = [99; 0];
+   |                    ^^
+
 error[E0308]: mismatched types
   --> $DIR/const-integer-bool-ops.rs:62:19
    |
 LL | const Y5: usize = 42.0 != 42.0;
    |                   ^^^^^^^^^^^^ expected `usize`, found `bool`
 
+note: erroneous constant encountered
+  --> $DIR/const-integer-bool-ops.rs:65:20
+   |
+LL | const ARRR5: [i32; Y5] = [99; 0];
+   |                    ^^
+
 error: aborting due to 18 previous errors
 
 For more information about this error, try `rustc --explain E0308`.

tests/ui/consts/const-integer-bool-ops.stderr

@@ -4,6 +4,12 @@ error[E0764]: mutable references are not allowed in the final value of constants
 LL | const S: &'static mut str = &mut " hello ";
    |                             ^^^^^^^^^^^^^^
 
+note: erroneous constant encountered
+  --> $DIR/issue-76510.rs:7:70
+   |
+LL |         let s = transmute::<(*const u8, usize), &ManuallyDrop<str>>((S.as_ptr(), 3));
+   |                                                                      ^
+
 error: aborting due to 1 previous error
 
 For more information about this error, try `rustc --explain E0764`.

tests/ui/consts/const-mut-refs/issue-76510.stderr

@@ -11,6 +11,12 @@ help: use a trailing comma to create a tuple with one element
 LL | const TUP: (usize,) = (5usize << 64,);
    |                       +            ++
 
+note: erroneous constant encountered
+  --> $DIR/const-tup-index-span.rs:6:18
+   |
+LL | const ARR: [i32; TUP.0] = [];
+   |                  ^^^
+
 error: aborting due to 1 previous error
 
 For more information about this error, try `rustc --explain E0308`.

tests/ui/consts/const-tup-index-span.stderr

@@ -19,6 +19,24 @@ LL | |         core::mem::size_of::<T>()
 LL | |     }
    | |_____- `Tt::const_val` defined here
 
+note: erroneous constant encountered
+  --> $DIR/issue-54954.rs:11:15
+   |
+LL | fn f(z: [f32; ARR_LEN]) -> [f32; ARR_LEN] {
+   |               ^^^^^^^
+
+note: erroneous constant encountered
+  --> $DIR/issue-54954.rs:11:34
+   |
+LL | fn f(z: [f32; ARR_LEN]) -> [f32; ARR_LEN] {
+   |                                  ^^^^^^^
+
+note: erroneous constant encountered
+  --> $DIR/issue-54954.rs:16:22
+   |
+LL |     let _ = f([1f32; ARR_LEN]);
+   |                      ^^^^^^^
+
 error: aborting due to 2 previous errors
 
 Some errors have detailed explanations: E0379, E0790.

tests/ui/consts/issue-54954.stderr

@@ -4,5 +4,11 @@ error: missing type for `const` item
 LL |     const FIRST:  = 10;
    |                 ^ help: provide a type for the associated constant: `u8`
 
+note: erroneous constant encountered
+  --> $DIR/missing_assoc_const_type2.rs:18:5
+   |
+LL |     TwoDigits::FIRST as usize
+   |     ^^^^^^^^^^^^^^^^
+
 error: aborting due to 1 previous error