Rollup merge of #125667 - oli-obk:taintify, r=TaKO8Ki

Silence follow-up errors directly based on error types and regions

During type_of, we used to just return an error type if there were any errors encountered. This is problematic, because it means a struct declared as `struct Foo<'static>` will end up not finding any inherent or trait impls because those impl blocks' `Self` type will be `{type error}` instead of `Foo<'re_error>`. Now it's the latter, silencing nonsensical follow-up errors about `Foo` not having any methods.

Unfortunately that now allows for new follow-up errors, because borrowck treats `'re_error` as `'static`, causing nonsensical errors about non-error lifetimes not outliving `'static`. So what I also did was to just strip all outlives bounds that borrowck found, thus never letting it check them. There are probably more nuanced ways to do this, but I worried there would be other nonsensical errors if some outlives bounds were missing. Also from the test changes, it looked like an improvement everywhere.

2 files changed, 15 insertions, 3 deletions

diff --git a/tests/ui/parser/issues/issue-103748-ICE-wrong-braces.rs b/tests/ui/parser/issues/issue-103748-ICE-wrong-braces.rs
index f6aa39df27d..1c28c0632fa 100644
--- a/tests/ui/parser/issues/issue-103748-ICE-wrong-braces.rs
+++ b/tests/ui/parser/issues/issue-103748-ICE-wrong-braces.rs
@@ -5,3 +5,4 @@ struct Apple((Apple, Option(Banana ? Citron)));
 //~| ERROR expected one of `)` or `,`, found `Citron`
 //~| ERROR cannot find type `Citron` in this scope [E0412]
 //~| ERROR parenthesized type parameters may only be used with a `Fn` trait [E0214]
+//~| ERROR `Apple` has infinite size
diff --git a/tests/ui/parser/issues/issue-103748-ICE-wrong-braces.stderr b/tests/ui/parser/issues/issue-103748-ICE-wrong-braces.stderr
index 71d2d7b7975..b0d8b03ae08 100644
--- a/tests/ui/parser/issues/issue-103748-ICE-wrong-braces.stderr
+++ b/tests/ui/parser/issues/issue-103748-ICE-wrong-braces.stderr
@@ -34,7 +34,18 @@ help: use angle brackets instead
 LL | struct Apple((Apple, Option<Banana ? Citron>));
    |                            ~               ~
 
-error: aborting due to 4 previous errors
+error[E0072]: recursive type `Apple` has infinite size
+  --> $DIR/issue-103748-ICE-wrong-braces.rs:3:1
+   |
+LL | struct Apple((Apple, Option(Banana ? Citron)));
+   | ^^^^^^^^^^^^  ----- recursive without indirection
+   |
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to break the cycle
+   |
+LL | struct Apple((Box<Apple>, Option(Banana ? Citron)));
+   |               ++++     +
+
+error: aborting due to 5 previous errors
 
-Some errors have detailed explanations: E0214, E0412.
-For more information about an error, try `rustc --explain E0214`.
+Some errors have detailed explanations: E0072, E0214, E0412.
+For more information about an error, try `rustc --explain E0072`.