Rollup merge of #81351 - lcnr:big-money-big-prices, r=oli-obk

combine: stop eagerly evaluating consts

`super_relate_consts` eagerly evaluates constants which doesn't seem too great.

I now also finally understand why all of the unused substs test passed. The reason being
that we just evaluated the constants in `super_relate_consts` :laughing:

While this change isn't strictly necessary as evaluating consts here doesn't hurt, it still feels a lot cleaner to do it this way

r? `@oli-obk` `@nikomatsakis`

12 files changed, 85 insertions, 9 deletions

diff --git a/src/test/ui/const-generics/issues/issue-69654-run-pass.rs b/src/test/ui/const-generics/issues/issue-69654-run-pass.rs
index bbfd2183b06..45318ca68fc 100644
--- a/src/test/ui/const-generics/issues/issue-69654-run-pass.rs
+++ b/src/test/ui/const-generics/issues/issue-69654-run-pass.rs
@@ -1,4 +1,3 @@
-// run-pass
 #![feature(const_generics)]
 #![allow(incomplete_features, unused_braces)]
 
@@ -15,4 +14,5 @@ where
 
 fn main() {
     Foo::foo();
+    //~^ ERROR the function or associated item
 }
diff --git a/src/test/ui/const-generics/issues/issue-69654-run-pass.stderr b/src/test/ui/const-generics/issues/issue-69654-run-pass.stderr
new file mode 100644
index 00000000000..a82a60696b3
--- /dev/null
+++ b/src/test/ui/const-generics/issues/issue-69654-run-pass.stderr
@@ -0,0 +1,15 @@
+error[E0599]: the function or associated item `foo` exists for struct `Foo<{_: usize}>`, but its trait bounds were not satisfied
+  --> $DIR/issue-69654-run-pass.rs:16:10
+   |
+LL | struct Foo<const N: usize> {}
+   | -------------------------- function or associated item `foo` not found for this
+...
+LL |     Foo::foo();
+   |          ^^^ function or associated item cannot be called on `Foo<{_: usize}>` due to unsatisfied trait bounds
+   |
+   = note: the following trait bounds were not satisfied:
+           `[u8; _]: Bar<[(); _]>`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0599`.
diff --git a/src/test/ui/const-generics/issues/issue-69654.rs b/src/test/ui/const-generics/issues/issue-69654.rs
index 7e775999ebd..b1214b12a14 100644
--- a/src/test/ui/const-generics/issues/issue-69654.rs
+++ b/src/test/ui/const-generics/issues/issue-69654.rs
@@ -15,4 +15,5 @@ where
 
 fn main() {
     Foo::foo();
+    //~^ ERROR the function or associated item
 }
diff --git a/src/test/ui/const-generics/issues/issue-69654.stderr b/src/test/ui/const-generics/issues/issue-69654.stderr
index 70af7bf25d8..0ce7640f685 100644
--- a/src/test/ui/const-generics/issues/issue-69654.stderr
+++ b/src/test/ui/const-generics/issues/issue-69654.stderr
@@ -4,6 +4,19 @@ error[E0423]: expected value, found type parameter `T`
 LL | impl<T> Bar<T> for [u8; T] {}
    |                         ^ not a value
 
-error: aborting due to previous error
+error[E0599]: the function or associated item `foo` exists for struct `Foo<{_: usize}>`, but its trait bounds were not satisfied
+  --> $DIR/issue-69654.rs:17:10
+   |
+LL | struct Foo<const N: usize> {}
+   | -------------------------- function or associated item `foo` not found for this
+...
+LL |     Foo::foo();
+   |          ^^^ function or associated item cannot be called on `Foo<{_: usize}>` due to unsatisfied trait bounds
+   |
+   = note: the following trait bounds were not satisfied:
+           `[u8; _]: Bar<[(); _]>`
+
+error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0423`.
+Some errors have detailed explanations: E0423, E0599.
+For more information about an error, try `rustc --explain E0423`.
diff --git a/src/test/ui/const-generics/occurs-check/unused-substs-1.rs b/src/test/ui/const-generics/occurs-check/unused-substs-1.rs
index f56687ecd93..6ded9f13bc4 100644
--- a/src/test/ui/const-generics/occurs-check/unused-substs-1.rs
+++ b/src/test/ui/const-generics/occurs-check/unused-substs-1.rs
@@ -1,4 +1,3 @@
-// build-pass
 #![feature(const_generics)]
 #![allow(incomplete_features)]
 
@@ -10,5 +9,5 @@ where
     A<N>: Bar<N>;
 
 fn main() {
-    let _ = A;
+    let _ = A; //~ERROR the trait bound
 }
diff --git a/src/test/ui/const-generics/occurs-check/unused-substs-1.stderr b/src/test/ui/const-generics/occurs-check/unused-substs-1.stderr
new file mode 100644
index 00000000000..6830288acc0
--- /dev/null
+++ b/src/test/ui/const-generics/occurs-check/unused-substs-1.stderr
@@ -0,0 +1,17 @@
+error[E0277]: the trait bound `A<{_: usize}>: Bar<{_: usize}>` is not satisfied
+  --> $DIR/unused-substs-1.rs:12:13
+   |
+LL | / struct A<const N: usize>
+LL | | where
+LL | |     A<N>: Bar<N>;
+   | |_________________- required by `A`
+...
+LL |       let _ = A;
+   |               ^ the trait `Bar<{_: usize}>` is not implemented for `A<{_: usize}>`
+   |
+   = help: the following implementations were found:
+             <A<7_usize> as Bar<N>>
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/const-generics/occurs-check/unused-substs-2.rs b/src/test/ui/const-generics/occurs-check/unused-substs-2.rs
index 12444ec5312..2d00141fbf7 100644
--- a/src/test/ui/const-generics/occurs-check/unused-substs-2.rs
+++ b/src/test/ui/const-generics/occurs-check/unused-substs-2.rs
@@ -1,4 +1,3 @@
-// check-pass
 #![feature(const_generics)]
 #![allow(incomplete_features)]
 
@@ -24,4 +23,6 @@ fn main() {
     // `t` is `ty::Infer(TyVar(_#1t))`
     // `foo` contains `ty::Infer(TyVar(_#1t))` in its substs
     t = foo;
+    //~^ ERROR mismatched types
+    //~| NOTE cyclic type
 }
diff --git a/src/test/ui/const-generics/occurs-check/unused-substs-2.stderr b/src/test/ui/const-generics/occurs-check/unused-substs-2.stderr
new file mode 100644
index 00000000000..9532fc21a31
--- /dev/null
+++ b/src/test/ui/const-generics/occurs-check/unused-substs-2.stderr
@@ -0,0 +1,9 @@
+error[E0308]: mismatched types
+  --> $DIR/unused-substs-2.rs:25:9
+   |
+LL |     t = foo;
+   |         ^^^ cyclic type of infinite size
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/const-generics/occurs-check/unused-substs-3.rs b/src/test/ui/const-generics/occurs-check/unused-substs-3.rs
index 187e27382fc..2e306f8c4c8 100644
--- a/src/test/ui/const-generics/occurs-check/unused-substs-3.rs
+++ b/src/test/ui/const-generics/occurs-check/unused-substs-3.rs
@@ -1,4 +1,3 @@
-// check-pass
 #![feature(const_generics)]
 #![allow(incomplete_features)]
 
@@ -15,4 +14,6 @@ fn main() {
     // `t` is `ty::Infer(TyVar(_#1t))`
     // `foo` contains `ty::Infer(TyVar(_#1t))` in its substs
     t = foo;
+    //~^ ERROR mismatched types
+    //~| NOTE cyclic type
 }
diff --git a/src/test/ui/const-generics/occurs-check/unused-substs-3.stderr b/src/test/ui/const-generics/occurs-check/unused-substs-3.stderr
new file mode 100644
index 00000000000..2551d68f974
--- /dev/null
+++ b/src/test/ui/const-generics/occurs-check/unused-substs-3.stderr
@@ -0,0 +1,12 @@
+error[E0308]: mismatched types
+  --> $DIR/unused-substs-3.rs:16:9
+   |
+LL |     t = foo;
+   |         ^^^
+   |         |
+   |         cyclic type of infinite size
+   |         help: try using a conversion method: `foo.to_vec()`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/const-generics/occurs-check/unused-substs-4.rs b/src/test/ui/const-generics/occurs-check/unused-substs-4.rs
index 8e42ceb6d70..9c7f5ab91ed 100644
--- a/src/test/ui/const-generics/occurs-check/unused-substs-4.rs
+++ b/src/test/ui/const-generics/occurs-check/unused-substs-4.rs
@@ -1,4 +1,3 @@
-// build-pass
 #![feature(const_generics)]
 #![allow(incomplete_features)]
 
@@ -8,5 +7,5 @@ fn bind<const N: usize>(value: [u8; N]) -> [u8; 3 + 4] {
 
 fn main() {
     let mut arr = Default::default();
-    arr = bind(arr);
+    arr = bind(arr); //~ ERROR mismatched type
 }
diff --git a/src/test/ui/const-generics/occurs-check/unused-substs-4.stderr b/src/test/ui/const-generics/occurs-check/unused-substs-4.stderr
new file mode 100644
index 00000000000..5685eedbdec
--- /dev/null
+++ b/src/test/ui/const-generics/occurs-check/unused-substs-4.stderr
@@ -0,0 +1,9 @@
+error[E0308]: mismatched types
+  --> $DIR/unused-substs-4.rs:10:11
+   |
+LL |     arr = bind(arr);
+   |           ^^^^^^^^^ encountered a self-referencing constant
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.