Auto merge of #145384 - ywxt:parallel-tests, r=jieyouxu

Add more tests for the parallel rustc

At the moment, the parallel frontend test cases are severely lacking. Althought some reported issues have been resolved, they haven't been added into the tests.

This PR arranges the resolved ICE issues and adds tests for them.

Whether it is worthwhile to add a separate test suite for the paralel frontend still requires futher discussion. But we are trying coveraging issues being resolved through capability of the existing UI test suite.

Discussion: [Zulip](https://rust-lang.zulipchat.com/#narrow/channel/233931-t-compiler.2Fmajor-changes/topic/Proposal.20for.20a.20dedicated.20test.20suite.20for.20t.E2.80.A6.20compiler-team.23906)

Related issues:
- rust-lang/rust#120760
- rust-lang/rust#124423 fixed by rust-lang/rust#140358
- rust-lang/rust#127971 fxied by rust-lang/rust#140358
- rust-lang/rust#120601 fixed by rust-lang/rust#127311

cc `@jieyouxu`

22 files changed, 722 insertions, 19 deletions

diff --git a/src/doc/rustc-dev-guide/src/tests/directives.md b/src/doc/rustc-dev-guide/src/tests/directives.md
index f4ba9a044e6..fbbeb7e97d3 100644
--- a/src/doc/rustc-dev-guide/src/tests/directives.md
+++ b/src/doc/rustc-dev-guide/src/tests/directives.md
@@ -111,6 +111,7 @@ for more details.
 | `forbid-output`                   | A pattern which must not appear in stderr/`cfail` output                                                                 | `ui`, `incremental`                          | Regex pattern                                                                           |
 | `run-flags`                       | Flags passed to the test executable                                                                                      | `ui`                                         | Arbitrary flags                                                                         |
 | `known-bug`                       | No error annotation needed due to known bug                                                                              | `ui`, `crashes`, `incremental`               | Issue number `#123456`                                                                  |
+| `compare-output-by-lines`         | Compare the output by lines, rather than as a single string                                                              | All                                          | N/A                                                                                     |
 
 [^check_stdout]: presently <!-- date-check: Oct 2024 --> this has a weird quirk
     where the test binary's stdout and stderr gets concatenated and then
diff --git a/src/doc/rustc-dev-guide/src/tests/ui.md b/src/doc/rustc-dev-guide/src/tests/ui.md
index 25dd5814cf6..d3a2c406402 100644
--- a/src/doc/rustc-dev-guide/src/tests/ui.md
+++ b/src/doc/rustc-dev-guide/src/tests/ui.md
@@ -95,6 +95,7 @@ will check for output files:
   [Normalization](#normalization)).
 - `dont-check-compiler-stderr` — Ignores stderr from the compiler.
 - `dont-check-compiler-stdout` — Ignores stdout from the compiler.
+- `compare-output-by-lines` — Some tests have non-deterministic orders of output, so we need to compare by lines.
 
 UI tests run with `-Zdeduplicate-diagnostics=no` flag which disables rustc's
 built-in diagnostic deduplication mechanism. This means you may see some
diff --git a/src/tools/compiletest/src/directives.rs b/src/tools/compiletest/src/directives.rs
index 00007aa1d66..f2ad049d526 100644
--- a/src/tools/compiletest/src/directives.rs
+++ b/src/tools/compiletest/src/directives.rs
@@ -205,6 +205,8 @@ pub struct TestProps {
     pub dont_require_annotations: HashSet<ErrorKind>,
     /// Whether pretty printers should be disabled in gdb.
     pub disable_gdb_pretty_printers: bool,
+    /// Compare the output by lines, rather than as a single string.
+    pub compare_output_by_lines: bool,
 }
 
 mod directives {
@@ -254,6 +256,7 @@ mod directives {
     // This isn't a real directive, just one that is probably mistyped often
     pub const INCORRECT_COMPILER_FLAGS: &'static str = "compiler-flags";
     pub const DISABLE_GDB_PRETTY_PRINTERS: &'static str = "disable-gdb-pretty-printers";
+    pub const COMPARE_OUTPUT_BY_LINES: &'static str = "compare-output-by-lines";
 }
 
 impl TestProps {
@@ -310,6 +313,7 @@ impl TestProps {
             add_core_stubs: false,
             dont_require_annotations: Default::default(),
             disable_gdb_pretty_printers: false,
+            compare_output_by_lines: false,
         }
     }
 
@@ -664,6 +668,11 @@ impl TestProps {
                         DISABLE_GDB_PRETTY_PRINTERS,
                         &mut self.disable_gdb_pretty_printers,
                     );
+                    config.set_name_directive(
+                        ln,
+                        COMPARE_OUTPUT_BY_LINES,
+                        &mut self.compare_output_by_lines,
+                    );
                 },
             );
 
diff --git a/src/tools/compiletest/src/directives/directive_names.rs b/src/tools/compiletest/src/directives/directive_names.rs
index 59690ff2602..0ef84fb4594 100644
--- a/src/tools/compiletest/src/directives/directive_names.rs
+++ b/src/tools/compiletest/src/directives/directive_names.rs
@@ -17,6 +17,7 @@ pub(crate) const KNOWN_DIRECTIVE_NAMES: &[&str] = &[
     "check-run-results",
     "check-stdout",
     "check-test-line-numbers-match",
+    "compare-output-by-lines",
     "compile-flags",
     "disable-gdb-pretty-printers",
     "doc-flags",
diff --git a/src/tools/compiletest/src/runtest.rs b/src/tools/compiletest/src/runtest.rs
index 2402ed9a950..739db8fa095 100644
--- a/src/tools/compiletest/src/runtest.rs
+++ b/src/tools/compiletest/src/runtest.rs
@@ -2754,7 +2754,11 @@ impl<'test> TestCx<'test> {
         // Wrapper tools set by `runner` might provide extra output on failure,
         // for example a WebAssembly runtime might print the stack trace of an
         // `unreachable` instruction by default.
-        let compare_output_by_lines = self.config.runner.is_some();
+        //
+        // Also, some tests like `ui/parallel-rustc` have non-deterministic
+        // orders of output, so we need to compare by lines.
+        let compare_output_by_lines =
+            self.props.compare_output_by_lines || self.config.runner.is_some();
 
         let tmp;
         let (expected, actual): (&str, &str) = if compare_output_by_lines {
diff --git a/tests/ui/parallel-rustc/cache-after-waiting-issue-111528.rs b/tests/ui/parallel-rustc/cache-after-waiting-issue-111528.rs
index 73d173022f6..a357040a4e4 100644
--- a/tests/ui/parallel-rustc/cache-after-waiting-issue-111528.rs
+++ b/tests/ui/parallel-rustc/cache-after-waiting-issue-111528.rs
@@ -1,16 +1,18 @@
+// Test for #111528, the ice issue cause waiting on a query that panicked
+//
 //@ compile-flags: -Z threads=16
 //@ build-fail
+//@ compare-output-by-lines
 
-#![crate_type="rlib"]
+#![crate_type = "rlib"]
 #![allow(warnings)]
 
-#[export_name="fail"]
-pub fn a() {
-}
+#[export_name = "fail"]
+pub fn a() {}
 
-#[export_name="fail"]
+#[export_name = "fail"]
 pub fn b() {
-//~^ ERROR symbol `fail` is already defined
+    //~^ ERROR symbol `fail` is already defined
 }
 
 fn main() {}
diff --git a/tests/ui/parallel-rustc/cache-after-waiting-issue-111528.stderr b/tests/ui/parallel-rustc/cache-after-waiting-issue-111528.stderr
index 7963165e31b..80f63733fb3 100644
--- a/tests/ui/parallel-rustc/cache-after-waiting-issue-111528.stderr
+++ b/tests/ui/parallel-rustc/cache-after-waiting-issue-111528.stderr
@@ -1,5 +1,5 @@
 error: symbol `fail` is already defined
-  --> $DIR/cache-after-waiting-issue-111528.rs:12:1
+  --> $DIR/cache-after-waiting-issue-111528.rs:14:1
    |
 LL | pub fn b() {
    | ^^^^^^^^^^
diff --git a/tests/ui/parallel-rustc/cycle_crash-issue-135870.rs b/tests/ui/parallel-rustc/cycle_crash-issue-135870.rs
new file mode 100644
index 00000000000..4407e3aca80
--- /dev/null
+++ b/tests/ui/parallel-rustc/cycle_crash-issue-135870.rs
@@ -0,0 +1,8 @@
+// Test for #135870, which causes a deadlock bug
+//
+//@ compile-flags: -Z threads=2
+//@ compare-output-by-lines
+
+const FOO: usize = FOO; //~ ERROR cycle detected when simplifying constant for the type system `FOO`
+
+fn main() {}
diff --git a/tests/ui/parallel-rustc/cycle_crash.stderr b/tests/ui/parallel-rustc/cycle_crash-issue-135870.stderr
index 7af3b8ee532..6e588d1f894 100644
--- a/tests/ui/parallel-rustc/cycle_crash.stderr
+++ b/tests/ui/parallel-rustc/cycle_crash-issue-135870.stderr
@@ -1,11 +1,11 @@
 error[E0391]: cycle detected when simplifying constant for the type system `FOO`
-  --> $DIR/cycle_crash.rs:3:1
+  --> $DIR/cycle_crash-issue-135870.rs:6:1
    |
 LL | const FOO: usize = FOO;
    | ^^^^^^^^^^^^^^^^
    |
 note: ...which requires const-evaluating + checking `FOO`...
-  --> $DIR/cycle_crash.rs:3:20
+  --> $DIR/cycle_crash-issue-135870.rs:6:20
    |
 LL | const FOO: usize = FOO;
    |                    ^^^
diff --git a/tests/ui/parallel-rustc/cycle_crash.rs b/tests/ui/parallel-rustc/cycle_crash.rs
deleted file mode 100644
index 94ae11aef39..00000000000
--- a/tests/ui/parallel-rustc/cycle_crash.rs
+++ /dev/null
@@ -1,5 +0,0 @@
-//@ compile-flags: -Z threads=2
-
-const FOO: usize = FOO; //~ERROR cycle detected when simplifying constant for the type system `FOO`
-
-fn main() {}
diff --git a/tests/ui/parallel-rustc/export-symbols-deadlock-issue-118205-2.rs b/tests/ui/parallel-rustc/export-symbols-deadlock-issue-118205-2.rs
index 024df728736..523b1b2d1f3 100644
--- a/tests/ui/parallel-rustc/export-symbols-deadlock-issue-118205-2.rs
+++ b/tests/ui/parallel-rustc/export-symbols-deadlock-issue-118205-2.rs
@@ -1,6 +1,10 @@
+// Test for #118205, which causes a deadlock bug
+//
 //@ compile-flags:-C extra-filename=-1 -Z threads=16
 //@ no-prefer-dynamic
 //@ build-pass
+//@ compare-output-by-lines
+
 #![crate_name = "crateresolve1"]
 #![crate_type = "lib"]
 
diff --git a/tests/ui/parallel-rustc/export-symbols-deadlock-issue-118205.rs b/tests/ui/parallel-rustc/export-symbols-deadlock-issue-118205.rs
index 3ccc1ea5f10..65f99c30643 100644
--- a/tests/ui/parallel-rustc/export-symbols-deadlock-issue-118205.rs
+++ b/tests/ui/parallel-rustc/export-symbols-deadlock-issue-118205.rs
@@ -1,5 +1,8 @@
+// Test for #118205, which causes a deadlock bug
+//
 //@ compile-flags: -Z threads=16
 //@ build-pass
+//@ compare-output-by-lines
 
 pub static GLOBAL: isize = 3;
 
diff --git a/tests/ui/parallel-rustc/hello_world.rs b/tests/ui/parallel-rustc/hello_world.rs
index 56698fe2489..57891b92da0 100644
--- a/tests/ui/parallel-rustc/hello_world.rs
+++ b/tests/ui/parallel-rustc/hello_world.rs
@@ -1,5 +1,8 @@
+// Test for the basic function of parallel front end
+//
 //@ compile-flags: -Z threads=8
 //@ run-pass
+//@ compare-output-by-lines
 
 fn main() {
     println!("Hello world!");
diff --git a/tests/ui/parallel-rustc/read-stolen-value-issue-111520.rs b/tests/ui/parallel-rustc/read-stolen-value-issue-111520.rs
index ea8ecb67859..a6b37e62913 100644
--- a/tests/ui/parallel-rustc/read-stolen-value-issue-111520.rs
+++ b/tests/ui/parallel-rustc/read-stolen-value-issue-111520.rs
@@ -1,18 +1,21 @@
+// Test for #111520, which causes an ice bug cause of reading stolen value
+//
 //@ compile-flags: -Z threads=16
 //@ run-pass
+//@ compare-output-by-lines
 
 #[repr(transparent)]
 struct Sched {
     i: i32,
 }
 impl Sched {
-    extern "C" fn get(self) -> i32 { self.i }
+    extern "C" fn get(self) -> i32 {
+        self.i
+    }
 }
 
 fn main() {
     let s = Sched { i: 4 };
-    let f = || -> i32 {
-        s.get()
-    };
+    let f = || -> i32 { s.get() };
     println!("f: {}", f());
 }
diff --git a/tests/ui/parallel-rustc/ty-variance-issue-124423.rs b/tests/ui/parallel-rustc/ty-variance-issue-124423.rs
new file mode 100644
index 00000000000..8d7f29f7764
--- /dev/null
+++ b/tests/ui/parallel-rustc/ty-variance-issue-124423.rs
@@ -0,0 +1,58 @@
+// Test for #124423, which causes an ice bug: only `variances_of` returns `&[ty::Variance]`
+//
+//@ compile-flags: -Z threads=16
+//@ compare-output-by-lines
+
+use std::fmt::Debug;
+
+fn elided(_: &impl Copy + 'a) -> _ { x }
+//~^ ERROR ambiguous `+` in a type
+//~| ERROR use of undeclared lifetime name `'a`
+//~| ERROR the placeholder `_` is not allowed within types on item signatures for return types
+
+fn explicit<'b>(_: &'a impl Copy + 'a) -> impl 'a { x }
+//~^ ERROR ambiguous `+` in a type
+//~| ERROR at least one trait must be specified
+//~| ERROR use of undeclared lifetime name `'a`
+//~| ERROR use of undeclared lifetime name `'a`
+//~| ERROR use of undeclared lifetime name `'a`
+
+fn elided2( impl 'b) -> impl 'a + 'a { x }
+//~^ ERROR expected one of `:` or `|`, found `'b`
+//~| ERROR expected identifier, found keyword `impl`
+//~| ERROR at least one trait must be specified
+//~| ERROR use of undeclared lifetime name `'a`
+//~| ERROR use of undeclared lifetime name `'a`
+
+fn explicit2<'a>(_: &'a impl Copy + 'a) -> impl Copy + 'a { x }
+//~^ ERROR ambiguous `+` in a type
+
+fn foo<'a>(_: &impl Copy + 'a) -> impl 'b + 'a { x }
+//~^ ERROR ambiguous `+` in a type
+//~| ERROR at least one trait must be specified
+//~| ERROR use of undeclared lifetime name `'b`
+
+fn elided3(_: &impl Copy + 'a) -> Box<dyn 'a> { Box::new(x) }
+//~^ ERROR ambiguous `+` in a type
+//~| ERROR use of undeclared lifetime name `'a`
+//~| ERROR use of undeclared lifetime name `'a`
+//~| ERROR at least one trait is required for an object type
+
+fn x<'b>(_: &'a impl Copy + 'a) -> Box<dyn 'b> { Box::u32(x) }
+//~^ ERROR ambiguous `+` in a type
+//~| ERROR use of undeclared lifetime name `'a`
+//~| ERROR use of undeclared lifetime name `'a`
+//~| ERROR at least one trait is required for an object type
+//~| ERROR no function or associated item named `u32` found for struct `Box<_, _>` in the current scope
+
+fn elided4(_: &impl Copy + 'a) ->  new  { x(x) }
+//~^ ERROR ambiguous `+` in a type
+//~| ERROR use of undeclared lifetime name `'a`
+//~| ERROR cannot find type `new` in this scope
+
+trait LifetimeTrait<'a> {}
+
+impl<'a> LifetimeTrait<'a> for &'a Box<dyn 'a> {}
+//~^ ERROR at least one trait is required for an object type
+
+fn main() {}
diff --git a/tests/ui/parallel-rustc/ty-variance-issue-124423.stderr b/tests/ui/parallel-rustc/ty-variance-issue-124423.stderr
new file mode 100644
index 00000000000..7ba89f75bd1
--- /dev/null
+++ b/tests/ui/parallel-rustc/ty-variance-issue-124423.stderr
@@ -0,0 +1,287 @@
+error: ambiguous `+` in a type
+  --> $DIR/ty-variance-issue-124423.rs:8:15
+   |
+LL | fn elided(_: &impl Copy + 'a) -> _ { x }
+   |               ^^^^^^^^^^^^^^
+   |
+help: try adding parentheses
+   |
+LL | fn elided(_: &(impl Copy + 'a)) -> _ { x }
+   |               +              +
+
+error: ambiguous `+` in a type
+  --> $DIR/ty-variance-issue-124423.rs:13:24
+   |
+LL | fn explicit<'b>(_: &'a impl Copy + 'a) -> impl 'a { x }
+   |                        ^^^^^^^^^^^^^^
+   |
+help: try adding parentheses
+   |
+LL | fn explicit<'b>(_: &'a (impl Copy + 'a)) -> impl 'a { x }
+   |                        +              +
+
+error: expected identifier, found keyword `impl`
+  --> $DIR/ty-variance-issue-124423.rs:20:13
+   |
+LL | fn elided2( impl 'b) -> impl 'a + 'a { x }
+   |             ^^^^ expected identifier, found keyword
+
+error: expected one of `:` or `|`, found `'b`
+  --> $DIR/ty-variance-issue-124423.rs:20:18
+   |
+LL | fn elided2( impl 'b) -> impl 'a + 'a { x }
+   |                  ^^ expected one of `:` or `|`
+
+error: ambiguous `+` in a type
+  --> $DIR/ty-variance-issue-124423.rs:27:25
+   |
+LL | fn explicit2<'a>(_: &'a impl Copy + 'a) -> impl Copy + 'a { x }
+   |                         ^^^^^^^^^^^^^^
+   |
+help: try adding parentheses
+   |
+LL | fn explicit2<'a>(_: &'a (impl Copy + 'a)) -> impl Copy + 'a { x }
+   |                         +              +
+
+error: ambiguous `+` in a type
+  --> $DIR/ty-variance-issue-124423.rs:30:16
+   |
+LL | fn foo<'a>(_: &impl Copy + 'a) -> impl 'b + 'a { x }
+   |                ^^^^^^^^^^^^^^
+   |
+help: try adding parentheses
+   |
+LL | fn foo<'a>(_: &(impl Copy + 'a)) -> impl 'b + 'a { x }
+   |                +              +
+
+error: ambiguous `+` in a type
+  --> $DIR/ty-variance-issue-124423.rs:35:16
+   |
+LL | fn elided3(_: &impl Copy + 'a) -> Box<dyn 'a> { Box::new(x) }
+   |                ^^^^^^^^^^^^^^
+   |
+help: try adding parentheses
+   |
+LL | fn elided3(_: &(impl Copy + 'a)) -> Box<dyn 'a> { Box::new(x) }
+   |                +              +
+
+error: ambiguous `+` in a type
+  --> $DIR/ty-variance-issue-124423.rs:41:17
+   |
+LL | fn x<'b>(_: &'a impl Copy + 'a) -> Box<dyn 'b> { Box::u32(x) }
+   |                 ^^^^^^^^^^^^^^
+   |
+help: try adding parentheses
+   |
+LL | fn x<'b>(_: &'a (impl Copy + 'a)) -> Box<dyn 'b> { Box::u32(x) }
+   |                 +              +
+
+error: ambiguous `+` in a type
+  --> $DIR/ty-variance-issue-124423.rs:48:16
+   |
+LL | fn elided4(_: &impl Copy + 'a) ->  new  { x(x) }
+   |                ^^^^^^^^^^^^^^
+   |
+help: try adding parentheses
+   |
+LL | fn elided4(_: &(impl Copy + 'a)) ->  new  { x(x) }
+   |                +              +
+
+error: at least one trait must be specified
+  --> $DIR/ty-variance-issue-124423.rs:13:43
+   |
+LL | fn explicit<'b>(_: &'a impl Copy + 'a) -> impl 'a { x }
+   |                                           ^^^^^^^
+
+error: at least one trait must be specified
+  --> $DIR/ty-variance-issue-124423.rs:20:25
+   |
+LL | fn elided2( impl 'b) -> impl 'a + 'a { x }
+   |                         ^^^^^^^^^^^^
+
+error: at least one trait must be specified
+  --> $DIR/ty-variance-issue-124423.rs:30:35
+   |
+LL | fn foo<'a>(_: &impl Copy + 'a) -> impl 'b + 'a { x }
+   |                                   ^^^^^^^^^^^^
+
+error[E0261]: use of undeclared lifetime name `'a`
+  --> $DIR/ty-variance-issue-124423.rs:8:27
+   |
+LL | fn elided(_: &impl Copy + 'a) -> _ { x }
+   |                           ^^ undeclared lifetime
+   |
+help: consider introducing lifetime `'a` here
+   |
+LL | fn elided<'a>(_: &impl Copy + 'a) -> _ { x }
+   |          ++++
+
+error[E0261]: use of undeclared lifetime name `'a`
+  --> $DIR/ty-variance-issue-124423.rs:13:21
+   |
+LL | fn explicit<'b>(_: &'a impl Copy + 'a) -> impl 'a { x }
+   |                     ^^ undeclared lifetime
+   |
+help: consider introducing lifetime `'a` here
+   |
+LL | fn explicit<'a, 'b>(_: &'a impl Copy + 'a) -> impl 'a { x }
+   |             +++
+
+error[E0261]: use of undeclared lifetime name `'a`
+  --> $DIR/ty-variance-issue-124423.rs:13:36
+   |
+LL | fn explicit<'b>(_: &'a impl Copy + 'a) -> impl 'a { x }
+   |                                    ^^ undeclared lifetime
+   |
+help: consider introducing lifetime `'a` here
+   |
+LL | fn explicit<'a, 'b>(_: &'a impl Copy + 'a) -> impl 'a { x }
+   |             +++
+
+error[E0261]: use of undeclared lifetime name `'a`
+  --> $DIR/ty-variance-issue-124423.rs:13:48
+   |
+LL | fn explicit<'b>(_: &'a impl Copy + 'a) -> impl 'a { x }
+   |                                                ^^ undeclared lifetime
+   |
+help: consider introducing lifetime `'a` here
+   |
+LL | fn explicit<'a, 'b>(_: &'a impl Copy + 'a) -> impl 'a { x }
+   |             +++
+
+error[E0261]: use of undeclared lifetime name `'a`
+  --> $DIR/ty-variance-issue-124423.rs:20:30
+   |
+LL | fn elided2( impl 'b) -> impl 'a + 'a { x }
+   |                              ^^ undeclared lifetime
+   |
+help: consider introducing lifetime `'a` here
+   |
+LL | fn elided2<'a>( impl 'b) -> impl 'a + 'a { x }
+   |           ++++
+
+error[E0261]: use of undeclared lifetime name `'a`
+  --> $DIR/ty-variance-issue-124423.rs:20:35
+   |
+LL | fn elided2( impl 'b) -> impl 'a + 'a { x }
+   |                                   ^^ undeclared lifetime
+   |
+help: consider introducing lifetime `'a` here
+   |
+LL | fn elided2<'a>( impl 'b) -> impl 'a + 'a { x }
+   |           ++++
+
+error[E0261]: use of undeclared lifetime name `'b`
+  --> $DIR/ty-variance-issue-124423.rs:30:40
+   |
+LL | fn foo<'a>(_: &impl Copy + 'a) -> impl 'b + 'a { x }
+   |                                        ^^ undeclared lifetime
+   |
+help: consider introducing lifetime `'b` here
+   |
+LL | fn foo<'b, 'a>(_: &impl Copy + 'a) -> impl 'b + 'a { x }
+   |        +++
+
+error[E0261]: use of undeclared lifetime name `'a`
+  --> $DIR/ty-variance-issue-124423.rs:35:28
+   |
+LL | fn elided3(_: &impl Copy + 'a) -> Box<dyn 'a> { Box::new(x) }
+   |                            ^^ undeclared lifetime
+   |
+help: consider introducing lifetime `'a` here
+   |
+LL | fn elided3<'a>(_: &impl Copy + 'a) -> Box<dyn 'a> { Box::new(x) }
+   |           ++++
+
+error[E0261]: use of undeclared lifetime name `'a`
+  --> $DIR/ty-variance-issue-124423.rs:35:43
+   |
+LL | fn elided3(_: &impl Copy + 'a) -> Box<dyn 'a> { Box::new(x) }
+   |                                           ^^ undeclared lifetime
+   |
+help: consider introducing lifetime `'a` here
+   |
+LL | fn elided3<'a>(_: &impl Copy + 'a) -> Box<dyn 'a> { Box::new(x) }
+   |           ++++
+
+error[E0261]: use of undeclared lifetime name `'a`
+  --> $DIR/ty-variance-issue-124423.rs:41:14
+   |
+LL | fn x<'b>(_: &'a impl Copy + 'a) -> Box<dyn 'b> { Box::u32(x) }
+   |              ^^ undeclared lifetime
+   |
+help: consider introducing lifetime `'a` here
+   |
+LL | fn x<'a, 'b>(_: &'a impl Copy + 'a) -> Box<dyn 'b> { Box::u32(x) }
+   |      +++
+
+error[E0261]: use of undeclared lifetime name `'a`
+  --> $DIR/ty-variance-issue-124423.rs:41:29
+   |
+LL | fn x<'b>(_: &'a impl Copy + 'a) -> Box<dyn 'b> { Box::u32(x) }
+   |                             ^^ undeclared lifetime
+   |
+help: consider introducing lifetime `'a` here
+   |
+LL | fn x<'a, 'b>(_: &'a impl Copy + 'a) -> Box<dyn 'b> { Box::u32(x) }
+   |      +++
+
+error[E0261]: use of undeclared lifetime name `'a`
+  --> $DIR/ty-variance-issue-124423.rs:48:28
+   |
+LL | fn elided4(_: &impl Copy + 'a) ->  new  { x(x) }
+   |                            ^^ undeclared lifetime
+   |
+help: consider introducing lifetime `'a` here
+   |
+LL | fn elided4<'a>(_: &impl Copy + 'a) ->  new  { x(x) }
+   |           ++++
+
+error[E0412]: cannot find type `new` in this scope
+  --> $DIR/ty-variance-issue-124423.rs:48:36
+   |
+LL | fn elided4(_: &impl Copy + 'a) ->  new  { x(x) }
+   |                                    ^^^ not found in this scope
+
+error[E0224]: at least one trait is required for an object type
+  --> $DIR/ty-variance-issue-124423.rs:35:39
+   |
+LL | fn elided3(_: &impl Copy + 'a) -> Box<dyn 'a> { Box::new(x) }
+   |                                       ^^^^^^
+
+error[E0224]: at least one trait is required for an object type
+  --> $DIR/ty-variance-issue-124423.rs:41:40
+   |
+LL | fn x<'b>(_: &'a impl Copy + 'a) -> Box<dyn 'b> { Box::u32(x) }
+   |                                        ^^^^^^
+
+error[E0224]: at least one trait is required for an object type
+  --> $DIR/ty-variance-issue-124423.rs:55:40
+   |
+LL | impl<'a> LifetimeTrait<'a> for &'a Box<dyn 'a> {}
+   |                                        ^^^^^^
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/ty-variance-issue-124423.rs:8:34
+   |
+LL | fn elided(_: &impl Copy + 'a) -> _ { x }
+   |                                  ^ not allowed in type signatures
+
+error[E0599]: no function or associated item named `u32` found for struct `Box<_, _>` in the current scope
+  --> $DIR/ty-variance-issue-124423.rs:41:55
+   |
+LL | fn x<'b>(_: &'a impl Copy + 'a) -> Box<dyn 'b> { Box::u32(x) }
+   |                                                       ^^^ function or associated item not found in `Box<_, _>`
+   |
+note: if you're trying to build a new `Box<_, _>` consider using one of the following associated functions:
+      Box::<T>::new
+      Box::<T>::new_uninit
+      Box::<T>::new_zeroed
+      Box::<T>::try_new
+      and 22 others
+  --> $SRC_DIR/alloc/src/boxed.rs:LL:COL
+
+error: aborting due to 30 previous errors
+
+Some errors have detailed explanations: E0121, E0224, E0261, E0412, E0599.
+For more information about an error, try `rustc --explain E0121`.
diff --git a/tests/ui/parallel-rustc/ty-variance-issue-127971.rs b/tests/ui/parallel-rustc/ty-variance-issue-127971.rs
new file mode 100644
index 00000000000..a17916843e7
--- /dev/null
+++ b/tests/ui/parallel-rustc/ty-variance-issue-127971.rs
@@ -0,0 +1,25 @@
+// Test for #127971, which causes an ice bug: only `variances_of` returns `&[ty::Variance]`
+//
+//@ compile-flags: -Z threads=16
+//@ compare-output-by-lines
+
+use std::fmt::Debug;
+
+fn elided(_: &impl Copy + 'a) -> _ { x }
+//~^ ERROR ambiguous `+` in a type
+//~| ERROR use of undeclared lifetime name `'a`
+//~| ERROR the placeholder `_` is not allowed within types on item signatures for return types
+
+fn foo<'a>(_: &impl Copy + 'a) -> impl 'b + 'a { x }
+//~^ ERROR ambiguous `+` in a type
+//~| ERROR at least one trait must be specified
+//~| ERROR use of undeclared lifetime name `'b`
+
+fn x<'b>(_: &'a impl Copy + 'a) -> Box<dyn 'b> { Box::u32(x) }
+//~^ ERROR ambiguous `+` in a type
+//~| ERROR use of undeclared lifetime name `'a`
+//~| ERROR use of undeclared lifetime name `'a`
+//~| ERROR at least one trait is required for an object type
+//~| ERROR no function or associated item named `u32` found for struct `Box<_, _>` in the current scope
+
+fn main() {}
diff --git a/tests/ui/parallel-rustc/ty-variance-issue-127971.stderr b/tests/ui/parallel-rustc/ty-variance-issue-127971.stderr
new file mode 100644
index 00000000000..9929d3ee22c
--- /dev/null
+++ b/tests/ui/parallel-rustc/ty-variance-issue-127971.stderr
@@ -0,0 +1,113 @@
+error: ambiguous `+` in a type
+  --> $DIR/ty-variance-issue-127971.rs:8:15
+   |
+LL | fn elided(_: &impl Copy + 'a) -> _ { x }
+   |               ^^^^^^^^^^^^^^
+   |
+help: try adding parentheses
+   |
+LL | fn elided(_: &(impl Copy + 'a)) -> _ { x }
+   |               +              +
+
+error: ambiguous `+` in a type
+  --> $DIR/ty-variance-issue-127971.rs:13:16
+   |
+LL | fn foo<'a>(_: &impl Copy + 'a) -> impl 'b + 'a { x }
+   |                ^^^^^^^^^^^^^^
+   |
+help: try adding parentheses
+   |
+LL | fn foo<'a>(_: &(impl Copy + 'a)) -> impl 'b + 'a { x }
+   |                +              +
+
+error: ambiguous `+` in a type
+  --> $DIR/ty-variance-issue-127971.rs:18:17
+   |
+LL | fn x<'b>(_: &'a impl Copy + 'a) -> Box<dyn 'b> { Box::u32(x) }
+   |                 ^^^^^^^^^^^^^^
+   |
+help: try adding parentheses
+   |
+LL | fn x<'b>(_: &'a (impl Copy + 'a)) -> Box<dyn 'b> { Box::u32(x) }
+   |                 +              +
+
+error: at least one trait must be specified
+  --> $DIR/ty-variance-issue-127971.rs:13:35
+   |
+LL | fn foo<'a>(_: &impl Copy + 'a) -> impl 'b + 'a { x }
+   |                                   ^^^^^^^^^^^^
+
+error[E0261]: use of undeclared lifetime name `'a`
+  --> $DIR/ty-variance-issue-127971.rs:8:27
+   |
+LL | fn elided(_: &impl Copy + 'a) -> _ { x }
+   |                           ^^ undeclared lifetime
+   |
+help: consider introducing lifetime `'a` here
+   |
+LL | fn elided<'a>(_: &impl Copy + 'a) -> _ { x }
+   |          ++++
+
+error[E0261]: use of undeclared lifetime name `'b`
+  --> $DIR/ty-variance-issue-127971.rs:13:40
+   |
+LL | fn foo<'a>(_: &impl Copy + 'a) -> impl 'b + 'a { x }
+   |                                        ^^ undeclared lifetime
+   |
+help: consider introducing lifetime `'b` here
+   |
+LL | fn foo<'b, 'a>(_: &impl Copy + 'a) -> impl 'b + 'a { x }
+   |        +++
+
+error[E0261]: use of undeclared lifetime name `'a`
+  --> $DIR/ty-variance-issue-127971.rs:18:14
+   |
+LL | fn x<'b>(_: &'a impl Copy + 'a) -> Box<dyn 'b> { Box::u32(x) }
+   |              ^^ undeclared lifetime
+   |
+help: consider introducing lifetime `'a` here
+   |
+LL | fn x<'a, 'b>(_: &'a impl Copy + 'a) -> Box<dyn 'b> { Box::u32(x) }
+   |      +++
+
+error[E0261]: use of undeclared lifetime name `'a`
+  --> $DIR/ty-variance-issue-127971.rs:18:29
+   |
+LL | fn x<'b>(_: &'a impl Copy + 'a) -> Box<dyn 'b> { Box::u32(x) }
+   |                             ^^ undeclared lifetime
+   |
+help: consider introducing lifetime `'a` here
+   |
+LL | fn x<'a, 'b>(_: &'a impl Copy + 'a) -> Box<dyn 'b> { Box::u32(x) }
+   |      +++
+
+error[E0224]: at least one trait is required for an object type
+  --> $DIR/ty-variance-issue-127971.rs:18:40
+   |
+LL | fn x<'b>(_: &'a impl Copy + 'a) -> Box<dyn 'b> { Box::u32(x) }
+   |                                        ^^^^^^
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/ty-variance-issue-127971.rs:8:34
+   |
+LL | fn elided(_: &impl Copy + 'a) -> _ { x }
+   |                                  ^ not allowed in type signatures
+
+error[E0599]: no function or associated item named `u32` found for struct `Box<_, _>` in the current scope
+  --> $DIR/ty-variance-issue-127971.rs:18:55
+   |
+LL | fn x<'b>(_: &'a impl Copy + 'a) -> Box<dyn 'b> { Box::u32(x) }
+   |                                                       ^^^ function or associated item not found in `Box<_, _>`
+   |
+note: if you're trying to build a new `Box<_, _>` consider using one of the following associated functions:
+      Box::<T>::new
+      Box::<T>::new_uninit
+      Box::<T>::new_zeroed
+      Box::<T>::try_new
+      and 22 others
+  --> $SRC_DIR/alloc/src/boxed.rs:LL:COL
+
+error: aborting due to 11 previous errors
+
+Some errors have detailed explanations: E0121, E0224, E0261, E0599.
+For more information about an error, try `rustc --explain E0121`.
diff --git a/tests/ui/parallel-rustc/undefined-function-issue-120760.rs b/tests/ui/parallel-rustc/undefined-function-issue-120760.rs
new file mode 100644
index 00000000000..2665c30945b
--- /dev/null
+++ b/tests/ui/parallel-rustc/undefined-function-issue-120760.rs
@@ -0,0 +1,71 @@
+// Test for #120760, which causes an ice bug: no index for a field
+//
+//@ compile-flags: -Z threads=45
+//@ edition: 2021
+//@ compare-output-by-lines
+
+type BoxFuture<T> = std::pin::Pin<Box<dyn std::future::Future<Output = T>>>;
+
+fn main() {
+    let _ = f();
+}
+
+async fn f() {
+    run("dependency").await; //~ ERROR cannot find function `run` in this scope
+}
+
+struct InMemoryStorage;
+
+pub struct User<'dep> {
+    pub name: &'a str, //~ ERROR use of undeclared lifetime name `'a`
+}
+
+impl<'a> StorageRequest<InMemoryStorage> for SaveUser<'a> {
+    fn execute(&self) -> BoxFuture<Result<(), String>> {
+        todo!()
+    }
+}
+
+trait Storage {
+    type Error;
+}
+
+impl Storage for InMemoryStorage {
+    type Error = String;
+}
+
+trait StorageRequestReturnType {
+    type Output;
+}
+
+trait StorageRequest<S: Storage>: StorageRequestReturnType {
+    fn execute(
+        &self,
+    ) -> BoxFuture<Result<<SaveUser as StorageRequestReturnType>::Output, <S as Storage>::Error>>;
+}
+
+pub struct SaveUser<'a> {
+    pub name: &'a str,
+}
+
+impl<'a> StorageRequestReturnType for SaveUser<'a> {
+    type Output = ();
+}
+
+impl<'dep> User<'dep> {
+    async fn save<S>(self)
+    where
+        S: Storage,
+        for<'a> SaveUser<'a>: StorageRequest<S>,
+    {
+        let _ = run("dependency").await; //~ ERROR cannot find function `run` in this scope
+    }
+}
+
+async fn execute<S>(dep: &str)
+where
+    S: Storage,
+    for<'a> SaveUser<'a>: StorageRequest<S>,
+{
+    User { dep }.save().await; //~ ERROR struct `User<'_>` has no field named `dep`
+}
diff --git a/tests/ui/parallel-rustc/undefined-function-issue-120760.stderr b/tests/ui/parallel-rustc/undefined-function-issue-120760.stderr
new file mode 100644
index 00000000000..87af5372219
--- /dev/null
+++ b/tests/ui/parallel-rustc/undefined-function-issue-120760.stderr
@@ -0,0 +1,35 @@
+error[E0261]: use of undeclared lifetime name `'a`
+  --> $DIR/undefined-function-issue-120760.rs:20:16
+   |
+LL |     pub name: &'a str,
+   |                ^^ undeclared lifetime
+   |
+help: consider introducing lifetime `'a` here
+   |
+LL | pub struct User<'a, 'dep> {
+   |                 +++
+
+error[E0425]: cannot find function `run` in this scope
+  --> $DIR/undefined-function-issue-120760.rs:14:5
+   |
+LL |     run("dependency").await;
+   |     ^^^ not found in this scope
+
+error[E0425]: cannot find function `run` in this scope
+  --> $DIR/undefined-function-issue-120760.rs:61:17
+   |
+LL |         let _ = run("dependency").await;
+   |                 ^^^ not found in this scope
+
+error[E0560]: struct `User<'_>` has no field named `dep`
+  --> $DIR/undefined-function-issue-120760.rs:70:12
+   |
+LL |     User { dep }.save().await;
+   |            ^^^ `User<'_>` does not have this field
+   |
+   = note: available fields are: `name`
+
+error: aborting due to 4 previous errors
+
+Some errors have detailed explanations: E0261, E0425, E0560.
+For more information about an error, try `rustc --explain E0261`.
diff --git a/tests/ui/parallel-rustc/unexpected-type-issue-120601.rs b/tests/ui/parallel-rustc/unexpected-type-issue-120601.rs
new file mode 100644
index 00000000000..2e215aa301a
--- /dev/null
+++ b/tests/ui/parallel-rustc/unexpected-type-issue-120601.rs
@@ -0,0 +1,28 @@
+// Test for #120601, which causes an ice bug cause of unexpected type
+//
+//@ compile-flags: -Z threads=40
+//@ compare-output-by-lines
+
+struct T;
+struct Tuple(i32);
+
+async fn foo() -> Result<(), ()> {
+    Unstable2(())
+}
+//~^^^ ERROR `async fn` is not permitted in Rust 2015
+//~^^^ ERROR cannot find function, tuple struct or tuple variant `Unstable2` in this scope
+
+async fn tuple() -> Tuple {
+    Tuple(1i32)
+}
+//~^^^ ERROR `async fn` is not permitted in Rust 2015
+
+async fn match_() {
+    match tuple() {
+        Tuple(_) => {}
+    }
+}
+//~^^^^^ ERROR `async fn` is not permitted in Rust 2015
+//~^^^^ ERROR  mismatched types
+
+fn main() {}
diff --git a/tests/ui/parallel-rustc/unexpected-type-issue-120601.stderr b/tests/ui/parallel-rustc/unexpected-type-issue-120601.stderr
new file mode 100644
index 00000000000..ed563bb0c4e
--- /dev/null
+++ b/tests/ui/parallel-rustc/unexpected-type-issue-120601.stderr
@@ -0,0 +1,52 @@
+error[E0670]: `async fn` is not permitted in Rust 2015
+  --> $DIR/unexpected-type-issue-120601.rs:9:1
+   |
+LL | async fn foo() -> Result<(), ()> {
+   | ^^^^^ to use `async fn`, switch to Rust 2018 or later
+   |
+   = help: pass `--edition 2024` to `rustc`
+   = note: for more on editions, read https://doc.rust-lang.org/edition-guide
+
+error[E0670]: `async fn` is not permitted in Rust 2015
+  --> $DIR/unexpected-type-issue-120601.rs:15:1
+   |
+LL | async fn tuple() -> Tuple {
+   | ^^^^^ to use `async fn`, switch to Rust 2018 or later
+   |
+   = help: pass `--edition 2024` to `rustc`
+   = note: for more on editions, read https://doc.rust-lang.org/edition-guide
+
+error[E0670]: `async fn` is not permitted in Rust 2015
+  --> $DIR/unexpected-type-issue-120601.rs:20:1
+   |
+LL | async fn match_() {
+   | ^^^^^ to use `async fn`, switch to Rust 2018 or later
+   |
+   = help: pass `--edition 2024` to `rustc`
+   = note: for more on editions, read https://doc.rust-lang.org/edition-guide
+
+error[E0425]: cannot find function, tuple struct or tuple variant `Unstable2` in this scope
+  --> $DIR/unexpected-type-issue-120601.rs:10:5
+   |
+LL |     Unstable2(())
+   |     ^^^^^^^^^ not found in this scope
+
+error[E0308]: mismatched types
+  --> $DIR/unexpected-type-issue-120601.rs:22:9
+   |
+LL |     match tuple() {
+   |           ------- this expression has type `impl Future<Output = Tuple>`
+LL |         Tuple(_) => {}
+   |         ^^^^^^^^ expected future, found `Tuple`
+   |
+   = note: expected opaque type `impl Future<Output = Tuple>`
+                   found struct `Tuple`
+help: consider `await`ing on the `Future`
+   |
+LL |     match tuple().await {
+   |                  ++++++
+
+error: aborting due to 5 previous errors
+
+Some errors have detailed explanations: E0308, E0425, E0670.
+For more information about an error, try `rustc --explain E0308`.