Auto merge of #133619 - matthiaskrgr:rollup-7ywaheb, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - #132782 (improvements on initial sysroot and libdir finding logics)
 - #133466 (Fix typos in pin.rs)
 - #133492 (bootstrap: allow skipping steps with start of path)
 - #133501 (support revealing defined opaque post borrowck)
 - #133530 (Use consistent wording in docs, use is zero instead of is 0)
 - #133538 (Better diagnostic for fn items in variadic functions)
 - #133590 (Rename `-Zparse-only`)

r? `@ghost`
`@rustbot` modify labels: rollup

24 files changed, 160 insertions, 20 deletions

diff --git a/tests/ui/c-variadic/fn-item-diagnostic-issue-69232.rs b/tests/ui/c-variadic/fn-item-diagnostic-issue-69232.rs
new file mode 100644
index 00000000000..d0ef91b22b2
--- /dev/null
+++ b/tests/ui/c-variadic/fn-item-diagnostic-issue-69232.rs
@@ -0,0 +1,13 @@
+// https://github.com/rust-lang/rust/issues/69232
+
+extern "C" {
+    fn foo(x: usize, ...);
+}
+
+fn test() -> u8 {
+    127
+}
+
+fn main() {
+    unsafe { foo(1, test) }; //~ ERROR can't pass a function item to a variadic function
+}
diff --git a/tests/ui/c-variadic/fn-item-diagnostic-issue-69232.stderr b/tests/ui/c-variadic/fn-item-diagnostic-issue-69232.stderr
new file mode 100644
index 00000000000..6aa1c8a1091
--- /dev/null
+++ b/tests/ui/c-variadic/fn-item-diagnostic-issue-69232.stderr
@@ -0,0 +1,16 @@
+error[E0617]: can't pass a function item to a variadic function
+  --> $DIR/fn-item-diagnostic-issue-69232.rs:12:21
+   |
+LL |     unsafe { foo(1, test) };
+   |                     ^^^^
+   |
+   = help: a function item is zero-sized and needs to be cast into a function pointer to be used in FFI
+   = note: for more information on function items, visit https://doc.rust-lang.org/reference/types/function-item.html
+help: use a function pointer instead
+   |
+LL |     unsafe { foo(1, test as fn() -> u8) };
+   |                          +++++++++++++
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0617`.
diff --git a/tests/ui/c-variadic/issue-32201.rs b/tests/ui/c-variadic/issue-32201.rs
index f27bb1c2eb5..434711b7523 100644
--- a/tests/ui/c-variadic/issue-32201.rs
+++ b/tests/ui/c-variadic/issue-32201.rs
@@ -7,7 +7,8 @@ fn bar(_: *const u8) {}
 fn main() {
     unsafe {
         foo(0, bar);
-        //~^ ERROR can't pass `fn(*const u8) {bar}` to variadic function
-        //~| HELP cast the value to `fn(*const u8)`
+        //~^ ERROR can't pass a function item to a variadic function
+        //~| HELP a function item is zero-sized and needs to be cast into a function pointer to be used in FFI
+        ////~| HELP use a function pointer instead
     }
 }
diff --git a/tests/ui/c-variadic/issue-32201.stderr b/tests/ui/c-variadic/issue-32201.stderr
index 352db9f62f6..1cd85d7f07a 100644
--- a/tests/ui/c-variadic/issue-32201.stderr
+++ b/tests/ui/c-variadic/issue-32201.stderr
@@ -1,8 +1,15 @@
-error[E0617]: can't pass `fn(*const u8) {bar}` to variadic function
+error[E0617]: can't pass a function item to a variadic function
   --> $DIR/issue-32201.rs:9:16
    |
 LL |         foo(0, bar);
-   |                ^^^ help: cast the value to `fn(*const u8)`: `bar as fn(*const u8)`
+   |                ^^^
+   |
+   = help: a function item is zero-sized and needs to be cast into a function pointer to be used in FFI
+   = note: for more information on function items, visit https://doc.rust-lang.org/reference/types/function-item.html
+help: use a function pointer instead
+   |
+LL |         foo(0, bar as fn(*const u8));
+   |                    ++++++++++++++++
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/error-codes/E0617.rs b/tests/ui/error-codes/E0617.rs
index b71ba0ed88b..4a38174bc6f 100644
--- a/tests/ui/error-codes/E0617.rs
+++ b/tests/ui/error-codes/E0617.rs
@@ -20,7 +20,8 @@ fn main() {
         //~^ ERROR can't pass `u16` to variadic function
         //~| HELP cast the value to `c_uint`
         printf(::std::ptr::null(), printf);
-        //~^ ERROR can't pass `unsafe extern "C" fn(*const i8, ...) {printf}` to variadic function
-        //~| HELP cast the value to `unsafe extern "C" fn(*const i8, ...)`
+        //~^ ERROR can't pass a function item to a variadic function
+        //~| HELP a function item is zero-sized and needs to be cast into a function pointer to be used in FFI
+        //~| HELP use a function pointer instead
     }
 }
diff --git a/tests/ui/error-codes/E0617.stderr b/tests/ui/error-codes/E0617.stderr
index ea91ad08292..7193463e028 100644
--- a/tests/ui/error-codes/E0617.stderr
+++ b/tests/ui/error-codes/E0617.stderr
@@ -28,16 +28,18 @@ error[E0617]: can't pass `u16` to variadic function
 LL |         printf(::std::ptr::null(), 0u16);
    |                                    ^^^^ help: cast the value to `c_uint`: `0u16 as c_uint`
 
-error[E0617]: can't pass `unsafe extern "C" fn(*const i8, ...) {printf}` to variadic function
+error[E0617]: can't pass a function item to a variadic function
   --> $DIR/E0617.rs:22:36
    |
 LL |         printf(::std::ptr::null(), printf);
    |                                    ^^^^^^
    |
-help: cast the value to `unsafe extern "C" fn(*const i8, ...)`
+   = help: a function item is zero-sized and needs to be cast into a function pointer to be used in FFI
+   = note: for more information on function items, visit https://doc.rust-lang.org/reference/types/function-item.html
+help: use a function pointer instead
    |
 LL |         printf(::std::ptr::null(), printf as unsafe extern "C" fn(*const i8, ...));
-   |                                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+   |                                           +++++++++++++++++++++++++++++++++++++++
 
 error: aborting due to 6 previous errors
 
diff --git a/tests/ui/generic-associated-types/parse/in-trait-impl.rs b/tests/ui/generic-associated-types/parse/in-trait-impl.rs
index 5ba42be3583..ef67fb18228 100644
--- a/tests/ui/generic-associated-types/parse/in-trait-impl.rs
+++ b/tests/ui/generic-associated-types/parse/in-trait-impl.rs
@@ -1,5 +1,5 @@
 //@ check-pass
-//@ compile-flags: -Z parse-only
+//@ compile-flags: -Z parse-crate-root-only
 
 impl<T> Baz for T where T: Foo {
     type Quux<'a> = <T as Foo>::Bar<'a, 'static>;
diff --git a/tests/ui/generic-associated-types/parse/in-trait.rs b/tests/ui/generic-associated-types/parse/in-trait.rs
index 913eceec0da..2add908d727 100644
--- a/tests/ui/generic-associated-types/parse/in-trait.rs
+++ b/tests/ui/generic-associated-types/parse/in-trait.rs
@@ -1,5 +1,5 @@
 //@ check-pass
-//@ compile-flags: -Z parse-only
+//@ compile-flags: -Z parse-crate-root-only
 
 use std::ops::Deref;
 use std::fmt::Debug;
diff --git a/tests/ui/impl-trait/impl-trait-plus-priority.rs b/tests/ui/impl-trait/impl-trait-plus-priority.rs
index 5441a015ac0..5575493a17d 100644
--- a/tests/ui/impl-trait/impl-trait-plus-priority.rs
+++ b/tests/ui/impl-trait/impl-trait-plus-priority.rs
@@ -1,4 +1,4 @@
-//@ compile-flags: -Z parse-only
+//@ compile-flags: -Z parse-crate-root-only
 
 fn f() -> impl A + {} // OK
 fn f() -> impl A + B {} // OK
diff --git a/tests/ui/parser/assoc/assoc-oddities-1.rs b/tests/ui/parser/assoc/assoc-oddities-1.rs
index 246546ac034..c1b305a4eeb 100644
--- a/tests/ui/parser/assoc/assoc-oddities-1.rs
+++ b/tests/ui/parser/assoc/assoc-oddities-1.rs
@@ -1,4 +1,4 @@
-//@ compile-flags: -Z parse-only
+//@ compile-flags: -Z parse-crate-root-only
 
 fn main() {
     // following lines below parse and must not fail
diff --git a/tests/ui/parser/assoc/assoc-oddities-2.rs b/tests/ui/parser/assoc/assoc-oddities-2.rs
index aee2af41d62..82cf7d79c0d 100644
--- a/tests/ui/parser/assoc/assoc-oddities-2.rs
+++ b/tests/ui/parser/assoc/assoc-oddities-2.rs
@@ -1,4 +1,4 @@
-//@ compile-flags: -Z parse-only
+//@ compile-flags: -Z parse-crate-root-only
 
 fn main() {
     // see assoc-oddities-1 for explanation
diff --git a/tests/ui/parser/bounds-type.rs b/tests/ui/parser/bounds-type.rs
index 7cee6def32f..ec0e83c314e 100644
--- a/tests/ui/parser/bounds-type.rs
+++ b/tests/ui/parser/bounds-type.rs
@@ -1,4 +1,4 @@
-//@ compile-flags: -Z parse-only
+//@ compile-flags: -Z parse-crate-root-only
 //@ edition: 2021
 
 struct S<
diff --git a/tests/ui/parser/impl-qpath.rs b/tests/ui/parser/impl-qpath.rs
index d7c4989b6e4..fed026792c9 100644
--- a/tests/ui/parser/impl-qpath.rs
+++ b/tests/ui/parser/impl-qpath.rs
@@ -1,5 +1,5 @@
 //@ check-pass
-//@ compile-flags: -Z parse-only
+//@ compile-flags: -Z parse-crate-root-only
 
 impl <*const u8>::AssocTy {} // OK
 impl <Type as Trait>::AssocTy {} // OK
diff --git a/tests/ui/parser/issues/issue-17904.rs b/tests/ui/parser/issues/issue-17904.rs
index 6f77d4bb086..99a3b139898 100644
--- a/tests/ui/parser/issues/issue-17904.rs
+++ b/tests/ui/parser/issues/issue-17904.rs
@@ -1,4 +1,4 @@
-//@ compile-flags: -Zparse-only
+//@ compile-flags: -Zparse-crate-root-only
 
 struct Baz<U> where U: Eq(U); //This is parsed as the new Fn* style parenthesis syntax.
 struct Baz<U> where U: Eq(U) -> R; // Notice this parses as well.
diff --git a/tests/ui/traits/const-traits/syntax.rs b/tests/ui/traits/const-traits/syntax.rs
index 1064713ac59..cfac6e0a93e 100644
--- a/tests/ui/traits/const-traits/syntax.rs
+++ b/tests/ui/traits/const-traits/syntax.rs
@@ -1,4 +1,4 @@
-//@ compile-flags: -Z parse-only
+//@ compile-flags: -Z parse-crate-root-only
 //@ check-pass
 
 #![feature(const_trait_bound_opt_out)]
diff --git a/tests/ui/traits/const-traits/tilde-const-syntax.rs b/tests/ui/traits/const-traits/tilde-const-syntax.rs
index d65ecae3d06..f9944c426cc 100644
--- a/tests/ui/traits/const-traits/tilde-const-syntax.rs
+++ b/tests/ui/traits/const-traits/tilde-const-syntax.rs
@@ -1,4 +1,4 @@
-//@ compile-flags: -Z parse-only
+//@ compile-flags: -Z parse-crate-root-only
 //@ check-pass
 
 #![feature(const_trait_impl)]
diff --git a/tests/ui/traits/const-traits/tilde-twice.rs b/tests/ui/traits/const-traits/tilde-twice.rs
index c3f9f8e6764..d341513b8a8 100644
--- a/tests/ui/traits/const-traits/tilde-twice.rs
+++ b/tests/ui/traits/const-traits/tilde-twice.rs
@@ -1,4 +1,4 @@
-//@ compile-flags: -Z parse-only
+//@ compile-flags: -Z parse-crate-root-only
 
 #![feature(const_trait_impl)]
 
diff --git a/tests/ui/traits/next-solver/dont-remap-tait-substs.rs b/tests/ui/traits/next-solver/opaques/dont-remap-tait-substs.rs
index 904bc179495..904bc179495 100644
--- a/tests/ui/traits/next-solver/dont-remap-tait-substs.rs
+++ b/tests/ui/traits/next-solver/opaques/dont-remap-tait-substs.rs
diff --git a/tests/ui/traits/next-solver/dont-type_of-tait-in-defining-scope.is_send.stderr b/tests/ui/traits/next-solver/opaques/dont-type_of-tait-in-defining-scope.is_send.stderr
index 158fefd1538..158fefd1538 100644
--- a/tests/ui/traits/next-solver/dont-type_of-tait-in-defining-scope.is_send.stderr
+++ b/tests/ui/traits/next-solver/opaques/dont-type_of-tait-in-defining-scope.is_send.stderr
diff --git a/tests/ui/traits/next-solver/dont-type_of-tait-in-defining-scope.not_send.stderr b/tests/ui/traits/next-solver/opaques/dont-type_of-tait-in-defining-scope.not_send.stderr
index 158fefd1538..158fefd1538 100644
--- a/tests/ui/traits/next-solver/dont-type_of-tait-in-defining-scope.not_send.stderr
+++ b/tests/ui/traits/next-solver/opaques/dont-type_of-tait-in-defining-scope.not_send.stderr
diff --git a/tests/ui/traits/next-solver/dont-type_of-tait-in-defining-scope.rs b/tests/ui/traits/next-solver/opaques/dont-type_of-tait-in-defining-scope.rs
index 10b746cc989..10b746cc989 100644
--- a/tests/ui/traits/next-solver/dont-type_of-tait-in-defining-scope.rs
+++ b/tests/ui/traits/next-solver/opaques/dont-type_of-tait-in-defining-scope.rs
diff --git a/tests/ui/traits/next-solver/opaques/no-define-in-wf-check.current.stderr b/tests/ui/traits/next-solver/opaques/no-define-in-wf-check.current.stderr
new file mode 100644
index 00000000000..9a28dc093c1
--- /dev/null
+++ b/tests/ui/traits/next-solver/opaques/no-define-in-wf-check.current.stderr
@@ -0,0 +1,34 @@
+error: unconstrained opaque type
+  --> $DIR/no-define-in-wf-check.rs:19:18
+   |
+LL |     type Tait1 = impl Sized;
+   |                  ^^^^^^^^^^
+   |
+   = note: `Tait1` must be used in combination with a concrete type within the same module
+
+error: unconstrained opaque type
+  --> $DIR/no-define-in-wf-check.rs:27:18
+   |
+LL |     type Tait1 = impl Sized;
+   |                  ^^^^^^^^^^
+   |
+   = note: `Tait1` must be used in combination with a concrete type within the same module
+
+error: unconstrained opaque type
+  --> $DIR/no-define-in-wf-check.rs:36:18
+   |
+LL |     type Tait1 = impl Sized;
+   |                  ^^^^^^^^^^
+   |
+   = note: `Tait1` must be used in combination with a concrete type within the same module
+
+error: unconstrained opaque type
+  --> $DIR/no-define-in-wf-check.rs:47:18
+   |
+LL |     type Tait1 = impl Sized;
+   |                  ^^^^^^^^^^
+   |
+   = note: `Tait1` must be used in combination with a concrete type within the same module
+
+error: aborting due to 4 previous errors
+
diff --git a/tests/ui/traits/next-solver/opaques/no-define-in-wf-check.rs b/tests/ui/traits/next-solver/opaques/no-define-in-wf-check.rs
new file mode 100644
index 00000000000..dd6df097da1
--- /dev/null
+++ b/tests/ui/traits/next-solver/opaques/no-define-in-wf-check.rs
@@ -0,0 +1,66 @@
+//@ revisions: current next
+//@ ignore-compare-mode-next-solver (explicit revisions)
+//@[next] compile-flags: -Znext-solver
+//@[next] check-pass
+
+// Regression test for trait-system-refactor-initiative#106. We previously
+// tried to define other opaques while checking that opaques are well-formed.
+//
+// This resulted in undesirable ambiguity
+
+#![feature(type_alias_impl_trait)]
+
+mod ex0 {
+    fn foo() -> (impl Sized, impl Sized) {
+        ((), ())
+    }
+}
+mod ex1 {
+    type Tait1 = impl Sized;
+    //[current]~^ ERROR unconstrained opaque type
+    fn foo(x: Tait1) -> impl Sized {
+        let () = x;
+    }
+}
+
+mod ex2 {
+    type Tait1 = impl Sized;
+    //[current]~^ ERROR unconstrained opaque type
+    type Tait2 = impl Sized;
+    fn foo(x: Tait1) -> Tait2 {
+        let () = x;
+    }
+}
+
+mod ex3 {
+    type Tait1 = impl Sized;
+    //[current]~^ ERROR unconstrained opaque type
+    trait Something<T> {}
+    impl<T, U> Something<U> for T {}
+    type Tait2 = impl Something<Tait1>;
+    fn foo(x: Tait1) -> Tait2 {
+        let () = x;
+    }
+}
+
+mod ex4 {
+    type Tait1 = impl Sized;
+    //[current]~^ ERROR unconstrained opaque type
+    trait Trait<U> {
+        type Assoc;
+    }
+
+    impl<T, U> Trait<U> for T {
+        type Assoc = T;
+    }
+
+    // ambiguity when checking that `Tait2` is wf
+    //
+    // ambiguity proving `(): Trait<Tait1>`.
+    type Tait2 = impl Trait<(), Assoc = impl Trait<Tait1>>;
+    fn foo(x: Tait1) -> Tait2 {
+        let () = x;
+    }
+}
+
+fn main() {}
diff --git a/tests/ui/traits/next-solver/select-alias-bound-as-param.rs b/tests/ui/traits/next-solver/opaques/select-alias-bound-as-param.rs
index fd40ef1f872..fd40ef1f872 100644
--- a/tests/ui/traits/next-solver/select-alias-bound-as-param.rs
+++ b/tests/ui/traits/next-solver/opaques/select-alias-bound-as-param.rs