From 2a00dda90258576e3adf5ecae0437a8fe6fadbcf Mon Sep 17 00:00:00 2001
From: Bastian Kauschke <bastian_kauschke@hotmail.de>
Date: Thu, 10 Sep 2020 19:43:53 +0200
Subject: [PATCH] miri: correctly deal with `ConstKind::Bound`

---
 compiler/rustc_mir/src/interpret/operand.rs   |  6 ++--
 .../ui/const-generics/issues/issue-73260.rs   | 20 +++++++++++++
 .../const-generics/issues/issue-73260.stderr  | 29 +++++++++++++++++++
 .../ui/const-generics/issues/issue-74634.rs   | 27 +++++++++++++++++
 .../const-generics/issues/issue-74634.stderr  | 10 +++++++
 5 files changed, 88 insertions(+), 4 deletions(-)
 create mode 100644 src/test/ui/const-generics/issues/issue-73260.rs
 create mode 100644 src/test/ui/const-generics/issues/issue-73260.stderr
 create mode 100644 src/test/ui/const-generics/issues/issue-74634.rs
 create mode 100644 src/test/ui/const-generics/issues/issue-74634.stderr

diff --git a/compiler/rustc_mir/src/interpret/operand.rs b/compiler/rustc_mir/src/interpret/operand.rs
index 57245696e576..136a2699d20b 100644
--- a/compiler/rustc_mir/src/interpret/operand.rs
+++ b/compiler/rustc_mir/src/interpret/operand.rs
@@ -549,7 +549,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         };
         // Early-return cases.
         let val_val = match val.val {
-            ty::ConstKind::Param(_) => throw_inval!(TooGeneric),
+            ty::ConstKind::Param(_) | ty::ConstKind::Bound(..) => throw_inval!(TooGeneric),
             ty::ConstKind::Error(_) => throw_inval!(TypeckError(ErrorReported)),
             ty::ConstKind::Unevaluated(def, substs, promoted) => {
                 let instance = self.resolve(def.did, substs)?;
@@ -561,9 +561,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 // happening.
                 return Ok(self.const_eval(GlobalId { instance, promoted }, val.ty)?);
             }
-            ty::ConstKind::Infer(..)
-            | ty::ConstKind::Bound(..)
-            | ty::ConstKind::Placeholder(..) => {
+            ty::ConstKind::Infer(..) | ty::ConstKind::Placeholder(..) => {
                 span_bug!(self.cur_span(), "const_to_op: Unexpected ConstKind {:?}", val)
             }
             ty::ConstKind::Value(val_val) => val_val,
diff --git a/src/test/ui/const-generics/issues/issue-73260.rs b/src/test/ui/const-generics/issues/issue-73260.rs
new file mode 100644
index 000000000000..351d6849af5d
--- /dev/null
+++ b/src/test/ui/const-generics/issues/issue-73260.rs
@@ -0,0 +1,20 @@
+// compile-flags: -Zsave-analysis
+
+#![feature(const_generics)]
+#![allow(incomplete_features)]
+struct Arr<const N: usize>
+where Assert::<{N < usize::max_value() / 2}>: IsTrue, //~ ERROR constant expression
+{
+}
+
+enum Assert<const CHECK: bool> {}
+
+trait IsTrue {}
+
+impl IsTrue for Assert<true> {}
+
+fn main() {
+    let x: Arr<{usize::max_value()}> = Arr {};
+    //~^ ERROR mismatched types
+    //~| ERROR mismatched types
+}
diff --git a/src/test/ui/const-generics/issues/issue-73260.stderr b/src/test/ui/const-generics/issues/issue-73260.stderr
new file mode 100644
index 000000000000..e22612ed5ea6
--- /dev/null
+++ b/src/test/ui/const-generics/issues/issue-73260.stderr
@@ -0,0 +1,29 @@
+error: constant expression depends on a generic parameter
+  --> $DIR/issue-73260.rs:6:47
+   |
+LL | where Assert::<{N < usize::max_value() / 2}>: IsTrue,
+   |                                               ^^^^^^
+   |
+   = note: this may fail depending on what value the parameter takes
+
+error[E0308]: mismatched types
+  --> $DIR/issue-73260.rs:17:12
+   |
+LL |     let x: Arr<{usize::max_value()}> = Arr {};
+   |            ^^^^^^^^^^^^^^^^^^^^^^^^^ expected `false`, found `true`
+   |
+   = note: expected type `false`
+              found type `true`
+
+error[E0308]: mismatched types
+  --> $DIR/issue-73260.rs:17:40
+   |
+LL |     let x: Arr<{usize::max_value()}> = Arr {};
+   |                                        ^^^ expected `false`, found `true`
+   |
+   = note: expected type `false`
+              found type `true`
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/const-generics/issues/issue-74634.rs b/src/test/ui/const-generics/issues/issue-74634.rs
new file mode 100644
index 000000000000..0f23fa92c367
--- /dev/null
+++ b/src/test/ui/const-generics/issues/issue-74634.rs
@@ -0,0 +1,27 @@
+#![feature(const_generics)]
+#![allow(incomplete_features)]
+
+trait If<const COND: bool> {}
+impl If<true> for () {}
+
+trait IsZero<const N: u8> {
+    type Answer;
+}
+
+struct True;
+struct False;
+
+impl<const N: u8> IsZero<N> for ()
+where (): If<{N == 0}> { //~ERROR constant expression
+    type Answer = True;
+}
+
+trait Foobar<const N: u8> {}
+
+impl<const N: u8> Foobar<N> for ()
+where (): IsZero<N, Answer = True> {}
+
+impl<const N: u8> Foobar<N> for ()
+where (): IsZero<N, Answer = False> {}
+
+fn main() {}
diff --git a/src/test/ui/const-generics/issues/issue-74634.stderr b/src/test/ui/const-generics/issues/issue-74634.stderr
new file mode 100644
index 000000000000..091a1ac7b998
--- /dev/null
+++ b/src/test/ui/const-generics/issues/issue-74634.stderr
@@ -0,0 +1,10 @@
+error: constant expression depends on a generic parameter
+  --> $DIR/issue-74634.rs:15:11
+   |
+LL | where (): If<{N == 0}> {
+   |           ^^^^^^^^^^^^
+   |
+   = note: this may fail depending on what value the parameter takes
+
+error: aborting due to previous error
+