Auto merge of rust-lang#78809 - vn-ki:fix-issue-76064, r=oli-obk

add error_occured field to ConstQualifs,

fix rust-lang#76064

I wasn't sure what `in_return_place` actually did and not sure why it returns `ConstQualifs` while it's sibling functions return `bool`. So I tried to make as minimal changes to the structure as possible. Please point out whether I have to refactor it or not.

r? `@oli-obk`
cc `@RalfJung`

Author: bors

compiler/rustc_middle/src/mir/query.rs

@@ -233,14 +233,15 @@ pub struct BorrowCheckResult<'tcx> {
 
 /// The result of the `mir_const_qualif` query.
 ///
-/// Each field corresponds to an implementer of the `Qualif` trait in
-/// `librustc_mir/transform/check_consts/qualifs.rs`. See that file for more information on each
+/// Each field (except `error_occured`) corresponds to an implementer of the `Qualif` trait in
+/// `rustc_mir/src/transform/check_consts/qualifs.rs`. See that file for more information on each
 /// `Qualif`.
 #[derive(Clone, Copy, Debug, Default, TyEncodable, TyDecodable, HashStable)]
 pub struct ConstQualifs {
     pub has_mut_interior: bool,
     pub needs_drop: bool,
     pub custom_eq: bool,
+    pub error_occured: Option<ErrorReported>,
 }
 
 /// After we borrow check a closure, we are left with various

compiler/rustc_mir/src/const_eval/eval_queries.rs

@@ -6,6 +6,7 @@ use crate::interpret::{
     ScalarMaybeUninit, StackPopCleanup,
 };
 
+use rustc_errors::ErrorReported;
 use rustc_hir::def::DefKind;
 use rustc_middle::mir;
 use rustc_middle::mir::interpret::ErrorHandled;
@@ -274,6 +275,16 @@ pub fn eval_to_allocation_raw_provider<'tcx>(
                 return Err(ErrorHandled::Reported(error_reported));
             }
         }
+        if !tcx.is_mir_available(def.did) {
+            tcx.sess.delay_span_bug(
+                tcx.def_span(def.did),
+                &format!("no MIR body is available for {:?}", def.did),
+            );
+            return Err(ErrorHandled::Reported(ErrorReported {}));
+        }
+        if let Some(error_reported) = tcx.mir_const_qualif_opt_const_arg(def).error_occured {
+            return Err(ErrorHandled::Reported(error_reported));
+        }
     }
 
     let is_static = tcx.is_static(def.did);

compiler/rustc_mir/src/transform/check_consts/qualifs.rs

@@ -2,18 +2,24 @@
 //!
 //! See the `Qualif` trait for more info.
 
+use rustc_errors::ErrorReported;
 use rustc_middle::mir::*;
 use rustc_middle::ty::{self, subst::SubstsRef, AdtDef, Ty};
 use rustc_span::DUMMY_SP;
 use rustc_trait_selection::traits;
 
 use super::ConstCx;
 
-pub fn in_any_value_of_ty(cx: &ConstCx<'_, 'tcx>, ty: Ty<'tcx>) -> ConstQualifs {
+pub fn in_any_value_of_ty(
+    cx: &ConstCx<'_, 'tcx>,
+    ty: Ty<'tcx>,
+    error_occured: Option<ErrorReported>,
+) -> ConstQualifs {
     ConstQualifs {
         has_mut_interior: HasMutInterior::in_any_value_of_ty(cx, ty),
         needs_drop: NeedsDrop::in_any_value_of_ty(cx, ty),
         custom_eq: CustomEq::in_any_value_of_ty(cx, ty),
+        error_occured,
     }
 }
 

compiler/rustc_mir/src/transform/check_consts/validation.rs

@@ -1,6 +1,6 @@
 //! The `Visitor` responsible for actually checking a `mir::Body` for invalid operations.
 
-use rustc_errors::{struct_span_err, Applicability, Diagnostic};
+use rustc_errors::{struct_span_err, Applicability, Diagnostic, ErrorReported};
 use rustc_hir::def_id::DefId;
 use rustc_hir::{self as hir, HirId, LangItem};
 use rustc_infer::infer::TyCtxtInferExt;
@@ -123,7 +123,11 @@ impl Qualifs<'mir, 'tcx> {
         has_mut_interior.get().contains(local) || self.indirectly_mutable(ccx, local, location)
     }
 
-    fn in_return_place(&mut self, ccx: &'mir ConstCx<'mir, 'tcx>) -> ConstQualifs {
+    fn in_return_place(
+        &mut self,
+        ccx: &'mir ConstCx<'mir, 'tcx>,
+        error_occured: Option<ErrorReported>,
+    ) -> ConstQualifs {
         // Find the `Return` terminator if one exists.
         //
         // If no `Return` terminator exists, this MIR is divergent. Just return the conservative
@@ -139,7 +143,7 @@ impl Qualifs<'mir, 'tcx> {
             .map(|(bb, _)| bb);
 
         let return_block = match return_block {
-            None => return qualifs::in_any_value_of_ty(ccx, ccx.body.return_ty()),
+            None => return qualifs::in_any_value_of_ty(ccx, ccx.body.return_ty(), error_occured),
             Some(bb) => bb,
         };
 
@@ -170,6 +174,7 @@ impl Qualifs<'mir, 'tcx> {
             needs_drop: self.needs_drop(ccx, RETURN_PLACE, return_loc),
             has_mut_interior: self.has_mut_interior(ccx, RETURN_PLACE, return_loc),
             custom_eq,
+            error_occured,
         }
     }
 }
@@ -181,7 +186,7 @@ pub struct Validator<'mir, 'tcx> {
     /// The span of the current statement.
     span: Span,
 
-    error_emitted: bool,
+    error_emitted: Option<ErrorReported>,
     secondary_errors: Vec<Diagnostic>,
 }
 
@@ -199,7 +204,7 @@ impl Validator<'mir, 'tcx> {
             span: ccx.body.span,
             ccx,
             qualifs: Default::default(),
-            error_emitted: false,
+            error_emitted: None,
             secondary_errors: Vec::new(),
         }
     }
@@ -266,7 +271,7 @@ impl Validator<'mir, 'tcx> {
         // If we got through const-checking without emitting any "primary" errors, emit any
         // "secondary" errors if they occurred.
         let secondary_errors = mem::take(&mut self.secondary_errors);
-        if !self.error_emitted {
+        if self.error_emitted.is_none() {
             for error in secondary_errors {
                 self.tcx.sess.diagnostic().emit_diagnostic(&error);
             }
@@ -276,7 +281,7 @@ impl Validator<'mir, 'tcx> {
     }
 
     pub fn qualifs_in_return_place(&mut self) -> ConstQualifs {
-        self.qualifs.in_return_place(self.ccx)
+        self.qualifs.in_return_place(self.ccx, self.error_emitted)
     }
 
     /// Emits an error if an expression cannot be evaluated in the current context.
@@ -318,7 +323,7 @@ impl Validator<'mir, 'tcx> {
 
         match op.importance() {
             ops::DiagnosticImportance::Primary => {
-                self.error_emitted = true;
+                self.error_emitted = Some(ErrorReported);
                 err.emit();
             }
 

src/test/compile-fail/issue-52443.rs

@@ -11,5 +11,4 @@ fn main() {
     //~| ERROR calls in constants are limited to constant functions
     //~| ERROR mutable references are not allowed in constants
     //~| ERROR calls in constants are limited to constant functions
-    //~| ERROR evaluation of constant value failed
 }

src/test/ui/const-generics/nested-type.full.stderr

@@ -4,13 +4,6 @@ error[E0015]: calls in constants are limited to constant functions, tuple struct
 LL |     Foo::<17>::value()
    |     ^^^^^^^^^^^^^^^^^^
 
-error[E0080]: evaluation of constant value failed
-  --> $DIR/nested-type.rs:16:5
-   |
-LL |     Foo::<17>::value()
-   |     ^^^^^^^^^^^^^^^^^^ calling non-const function `Foo::{constant#0}::Foo::<17_usize>::value`
-
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
-Some errors have detailed explanations: E0015, E0080.
-For more information about an error, try `rustc --explain E0015`.
+For more information about this error, try `rustc --explain E0015`.

src/test/ui/const-generics/nested-type.min.stderr

@@ -20,13 +20,6 @@ error[E0015]: calls in constants are limited to constant functions, tuple struct
 LL |     Foo::<17>::value()
    |     ^^^^^^^^^^^^^^^^^^
 
-error[E0080]: evaluation of constant value failed
-  --> $DIR/nested-type.rs:16:5
-   |
-LL |     Foo::<17>::value()
-   |     ^^^^^^^^^^^^^^^^^^ calling non-const function `Foo::{constant#0}::Foo::<17_usize>::value`
-
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0015, E0080.
-For more information about an error, try `rustc --explain E0015`.
+For more information about this error, try `rustc --explain E0015`.

src/test/ui/const-generics/nested-type.rs

@@ -15,7 +15,6 @@ struct Foo<const N: [u8; { //[min]~ ERROR `[u8; _]` is forbidden
 
     Foo::<17>::value()
     //~^ ERROR calls in constants are limited to constant functions
-    //~| ERROR evaluation of constant value failed
 }]>;
 
 fn main() {}

src/test/ui/consts/const-call.rs

@@ -5,5 +5,4 @@ fn f(x: usize) -> usize {
 fn main() {
     let _ = [0; f(2)];
     //~^ ERROR calls in constants are limited to constant functions
-    //~| ERROR evaluation of constant value failed
 }

src/test/ui/consts/const-call.stderr

@@ -4,13 +4,6 @@ error[E0015]: calls in constants are limited to constant functions, tuple struct
 LL |     let _ = [0; f(2)];
    |                 ^^^^
 
-error[E0080]: evaluation of constant value failed
-  --> $DIR/const-call.rs:6:17
-   |
-LL |     let _ = [0; f(2)];
-   |                 ^^^^ calling non-const function `f`
-
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
-Some errors have detailed explanations: E0015, E0080.
-For more information about an error, try `rustc --explain E0015`.
+For more information about this error, try `rustc --explain E0015`.

src/test/ui/consts/const-eval/issue-52442.rs

@@ -1,5 +1,4 @@
 fn main() {
     [();  { &loop { break } as *const _ as usize } ];
     //~^ ERROR casting pointers to integers in constants is unstable
-    //~| ERROR evaluation of constant value failed
 }

src/test/ui/consts/const-eval/issue-52442.stderr

@@ -7,13 +7,6 @@ LL |     [();  { &loop { break } as *const _ as usize } ];
    = note: see issue #51910 <https://github.com/rust-lang/rust/issues/51910> for more information
    = help: add `#![feature(const_raw_ptr_to_usize_cast)]` to the crate attributes to enable
 
-error[E0080]: evaluation of constant value failed
-  --> $DIR/issue-52442.rs:2:13
-   |
-LL |     [();  { &loop { break } as *const _ as usize } ];
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ "pointer-to-integer cast" needs an rfc before being allowed inside constants
-
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
-Some errors have detailed explanations: E0080, E0658.
-For more information about an error, try `rustc --explain E0080`.
+For more information about this error, try `rustc --explain E0658`.

src/test/ui/consts/const-eval/match-test-ptr-null.rs

@@ -5,7 +5,6 @@ fn main() {
     let _: [u8; 0] = [4; {
         match &1 as *const i32 as usize {
             //~^ ERROR casting pointers to integers in constants
-            //~| ERROR evaluation of constant value failed
             0 => 42,
             n => n,
         }

src/test/ui/consts/const-eval/match-test-ptr-null.stderr

@@ -7,13 +7,6 @@ LL |         match &1 as *const i32 as usize {
    = note: see issue #51910 <https://github.com/rust-lang/rust/issues/51910> for more information
    = help: add `#![feature(const_raw_ptr_to_usize_cast)]` to the crate attributes to enable
 
-error[E0080]: evaluation of constant value failed
-  --> $DIR/match-test-ptr-null.rs:6:15
-   |
-LL |         match &1 as *const i32 as usize {
-   |               ^^^^^^^^^^^^^^^^^^^^^^^^^ "pointer-to-integer cast" needs an rfc before being allowed inside constants
-
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
-Some errors have detailed explanations: E0080, E0658.
-For more information about an error, try `rustc --explain E0080`.
+For more information about this error, try `rustc --explain E0658`.

src/test/ui/consts/issue-68542-closure-in-array-len.rs

@@ -4,7 +4,6 @@
 
 struct Bug {
     a: [(); (|| { 0 })()] //~ ERROR calls in constants are limited to
-    //~^ ERROR evaluation of constant value failed
 }
 
 fn main() {}

src/test/ui/consts/issue-68542-closure-in-array-len.stderr

@@ -4,13 +4,6 @@ error[E0015]: calls in constants are limited to constant functions, tuple struct
 LL |     a: [(); (|| { 0 })()]
    |             ^^^^^^^^^^^^
 
-error[E0080]: evaluation of constant value failed
-  --> $DIR/issue-68542-closure-in-array-len.rs:6:13
-   |
-LL |     a: [(); (|| { 0 })()]
-   |             ^^^^^^^^^^^^ calling non-const function `Bug::a::{constant#0}::{closure#0}`
-
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
-Some errors have detailed explanations: E0015, E0080.
-For more information about an error, try `rustc --explain E0015`.
+For more information about this error, try `rustc --explain E0015`.

src/test/ui/consts/issue-76064.rs

@@ -0,0 +1,3 @@
+struct Bug([u8; panic!(1)]); //~ ERROR panicking in constants is unstable
+
+fn main() {}

src/test/ui/consts/issue-76064.stderr

@@ -0,0 +1,13 @@
+error[E0658]: panicking in constants is unstable
+  --> $DIR/issue-76064.rs:1:17
+   |
+LL | struct Bug([u8; panic!(1)]);
+   |                 ^^^^^^^^^
+   |
+   = note: see issue #51999 <https://github.com/rust-lang/rust/issues/51999> for more information
+   = help: add `#![feature(const_panic)]` to the crate attributes to enable
+   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.

src/test/ui/issues/issue-39559-2.rs

@@ -13,8 +13,6 @@ impl Dim for Dim3 {
 fn main() {
     let array: [usize; Dim3::dim()]
     //~^ ERROR E0015
-    //~| ERROR E0080
         = [0; Dim3::dim()];
         //~^ ERROR E0015
-        //~| ERROR E0080
 }

src/test/ui/issues/issue-39559-2.stderr

@@ -4,25 +4,12 @@ error[E0015]: calls in constants are limited to constant functions, tuple struct
 LL |     let array: [usize; Dim3::dim()]
    |                        ^^^^^^^^^^^
 
-error[E0080]: evaluation of constant value failed
-  --> $DIR/issue-39559-2.rs:14:24
-   |
-LL |     let array: [usize; Dim3::dim()]
-   |                        ^^^^^^^^^^^ calling non-const function `<Dim3 as Dim>::dim`
-
 error[E0015]: calls in constants are limited to constant functions, tuple structs and tuple variants
-  --> $DIR/issue-39559-2.rs:17:15
+  --> $DIR/issue-39559-2.rs:16:15
    |
 LL |         = [0; Dim3::dim()];
    |               ^^^^^^^^^^^
 
-error[E0080]: evaluation of constant value failed
-  --> $DIR/issue-39559-2.rs:17:15
-   |
-LL |         = [0; Dim3::dim()];
-   |               ^^^^^^^^^^^ calling non-const function `<Dim3 as Dim>::dim`
-
-error: aborting due to 4 previous errors
+error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0015, E0080.
-For more information about an error, try `rustc --explain E0015`.
+For more information about this error, try `rustc --explain E0015`.

src/test/ui/issues/issue-43105.rs

@@ -2,7 +2,6 @@ fn xyz() -> u8 { 42 }
 
 const NUM: u8 = xyz();
 //~^ ERROR calls in constants are limited to constant functions, tuple structs and tuple variants
-//~| ERROR any use of this value will cause an error [const_err]
 
 fn main() {
     match 1 {

src/test/ui/issues/issue-43105.stderr

@@ -4,28 +4,18 @@ error[E0015]: calls in constants are limited to constant functions, tuple struct
 LL | const NUM: u8 = xyz();
    |                 ^^^^^
 
-error: any use of this value will cause an error
-  --> $DIR/issue-43105.rs:3:17
-   |
-LL | const NUM: u8 = xyz();
-   | ----------------^^^^^-
-   |                 |
-   |                 calling non-const function `xyz`
-   |
-   = note: `#[deny(const_err)]` on by default
-
 error: could not evaluate constant pattern
-  --> $DIR/issue-43105.rs:9:9
+  --> $DIR/issue-43105.rs:8:9
    |
 LL |         NUM => unimplemented!(),
    |         ^^^
 
 error: could not evaluate constant pattern
-  --> $DIR/issue-43105.rs:9:9
+  --> $DIR/issue-43105.rs:8:9
    |
 LL |         NUM => unimplemented!(),
    |         ^^^
 
-error: aborting due to 4 previous errors
+error: aborting due to 3 previous errors
 
 For more information about this error, try `rustc --explain E0015`.

src/test/ui/issues/issue-52023-array-size-pointer-cast.rs

@@ -1,4 +1,3 @@
 fn main() {
     let _ = [0; (&0 as *const i32) as usize]; //~ ERROR casting pointers to integers in constants
-    //~^ ERROR evaluation of constant value failed
 }