Auto merge of #127311 - oli-obk:do_not_count_errors, r=compiler-errors

Avoid follow-up errors and ICEs after missing lifetime errors on data structures

Tuple struct constructors are functions, so when we call them typeck will use the signature tuple struct constructor function to provide type hints. Since typeck mostly ignores and erases lifetimes, we end up never seeing the error lifetime in writeback, thus not tainting the typeck result.

Now, we eagerly taint typeck results by tainting from `resolve_vars_if_possible`, which is called all over the place.

I did not carry over all the `crashes` test suite tests, as they are really all the same cause (missing or unknown lifetime names in tuple struct definitions or generic arg lists).

fixes #124262
fixes #124083
fixes #125155
fixes #125888
fixes #125992
fixes #126666
fixes #126648
fixes #127268
fixes #127266
fixes #127304

Author: bors

Diff for: .gitignore

@@ -50,6 +50,7 @@ build/
 /target
 /src/bootstrap/target
 /src/tools/x/target
+/inc-fat/
 # Created by default with `src/ci/docker/run.sh`
 /obj/
 /rustc-ice*

Diff for: compiler/rustc_infer/src/infer/mod.rs

@@ -1264,6 +1264,9 @@ impl<'tcx> InferCtxt<'tcx> {
     where
         T: TypeFoldable<TyCtxt<'tcx>>,
     {
+        if let Err(guar) = value.error_reported() {
+            self.set_tainted_by_errors(guar);
+        }
         if !value.has_non_region_infer() {
             return value;
         }

Diff for: tests/crashes/124083.rs

@@ -4,7 +4,6 @@ pub struct Foo<'a, 'b, T> {
     field1: dyn Bar<'a, 'b>,
     //~^ ERROR
     //~| ERROR
-    //~| ERROR
 }
 
 pub trait Bar<'x, 's, U>

Diff for: tests/crashes/124262.rs

@@ -5,7 +5,7 @@ LL |     field1: dyn Bar<'a, 'b>,
    |                 ^^^ expected 1 generic argument
    |
 note: trait defined here, with 1 generic parameter: `U`
-  --> $DIR/unable-fulfill-trait.rs:10:11
+  --> $DIR/unable-fulfill-trait.rs:9:11
    |
 LL | pub trait Bar<'x, 's, U>
    |           ^^^         -
@@ -20,24 +20,7 @@ error[E0227]: ambiguous lifetime bound, explicit lifetime bound required
 LL |     field1: dyn Bar<'a, 'b>,
    |             ^^^^^^^^^^^^^^^
 
-error[E0478]: lifetime bound not satisfied
-  --> $DIR/unable-fulfill-trait.rs:4:13
-   |
-LL |     field1: dyn Bar<'a, 'b>,
-   |             ^^^^^^^^^^^^^^^
-   |
-note: lifetime parameter instantiated with the lifetime `'b` as defined here
-  --> $DIR/unable-fulfill-trait.rs:3:20
-   |
-LL | pub struct Foo<'a, 'b, T> {
-   |                    ^^
-note: but lifetime parameter must outlive the lifetime `'a` as defined here
-  --> $DIR/unable-fulfill-trait.rs:3:16
-   |
-LL | pub struct Foo<'a, 'b, T> {
-   |                ^^
-
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0107, E0227, E0478.
+Some errors have detailed explanations: E0107, E0227.
 For more information about an error, try `rustc --explain E0107`.

Diff for: tests/crashes/125155.rs

@@ -7,25 +7,13 @@ LL |     pub fn call_me<Args: Sized, const IDX: usize, const FN: unsafe extern "
    = note: type parameters may not be used in the type of const parameters
 
 error[E0770]: the type of const parameters must not depend on other generic parameters
-  --> $DIR/issue-71381.rs:24:40
+  --> $DIR/issue-71381.rs:23:40
    |
 LL |         const FN: unsafe extern "C" fn(Args),
    |                                        ^^^^ the type must not depend on the parameter `Args`
    |
    = note: type parameters may not be used in the type of const parameters
 
-error[E0594]: cannot assign to `self.0`, which is behind a `&` reference
-  --> $DIR/issue-71381.rs:17:9
-   |
-LL |         self.0 = Self::trampiline::<Args, IDX, FN> as _
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `self` is a `&` reference, so the data it refers to cannot be written
-   |
-help: consider changing this to be a mutable reference
-   |
-LL |     pub fn call_me<Args: Sized, const IDX: usize, const FN: unsafe extern "C" fn(Args)>(&mut self) {
-   |                                                                                         ~~~~~~~~~
-
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0594, E0770.
-For more information about an error, try `rustc --explain E0594`.
+For more information about this error, try `rustc --explain E0770`.

Diff for: tests/crashes/125888.rs

@@ -7,7 +7,7 @@ LL |     pub fn call_me<Args: Sized, const IDX: usize, const FN: unsafe extern "
    = note: type parameters may not be used in the type of const parameters
 
 error[E0770]: the type of const parameters must not depend on other generic parameters
-  --> $DIR/issue-71381.rs:24:40
+  --> $DIR/issue-71381.rs:23:40
    |
 LL |         const FN: unsafe extern "C" fn(Args),
    |                                        ^^^^ the type must not depend on the parameter `Args`
@@ -23,25 +23,13 @@ LL |     pub fn call_me<Args: Sized, const IDX: usize, const FN: unsafe extern "
    = note: the only supported types are integers, `bool` and `char`
 
 error: using function pointers as const generic parameters is forbidden
-  --> $DIR/issue-71381.rs:24:19
+  --> $DIR/issue-71381.rs:23:19
    |
 LL |         const FN: unsafe extern "C" fn(Args),
    |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: the only supported types are integers, `bool` and `char`
 
-error[E0594]: cannot assign to `self.0`, which is behind a `&` reference
-  --> $DIR/issue-71381.rs:17:9
-   |
-LL |         self.0 = Self::trampiline::<Args, IDX, FN> as _
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `self` is a `&` reference, so the data it refers to cannot be written
-   |
-help: consider changing this to be a mutable reference
-   |
-LL |     pub fn call_me<Args: Sized, const IDX: usize, const FN: unsafe extern "C" fn(Args)>(&mut self) {
-   |                                                                                         ~~~~~~~~~
-
-error: aborting due to 5 previous errors
+error: aborting due to 4 previous errors
 
-Some errors have detailed explanations: E0594, E0770.
-For more information about an error, try `rustc --explain E0594`.
+For more information about this error, try `rustc --explain E0770`.

Diff for: tests/crashes/125992.rs

@@ -15,7 +15,6 @@ impl Test {
         //~^ ERROR: the type of const parameters must not depend on other generic parameters
         //[min]~^^ ERROR: using function pointers as const generic parameters is forbidden
         self.0 = Self::trampiline::<Args, IDX, FN> as _
-        //~^ ERROR: cannot assign to `self.0`
     }
 
     unsafe extern "C" fn trampiline<

Diff for: tests/crashes/126648.rs

@@ -15,7 +15,6 @@ fn gather_from_file(dir_entry: &foo::MissingItem) -> impl Iterator<Item = Lint>
 
 fn lint_files() -> impl Iterator<Item = foo::MissingItem> {
     //~^ ERROR: failed to resolve
-    //~| ERROR: `()` is not an iterator
     unimplemented!()
 }
 

Diff for: tests/crashes/126666.rs

@@ -1,11 +1,3 @@
-error[E0277]: `()` is not an iterator
-  --> $DIR/issue-72911.rs:16:20
-   |
-LL | fn lint_files() -> impl Iterator<Item = foo::MissingItem> {
-   |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `()` is not an iterator
-   |
-   = help: the trait `Iterator` is not implemented for `()`
-
 error[E0433]: failed to resolve: use of undeclared crate or module `foo`
   --> $DIR/issue-72911.rs:11:33
    |
@@ -18,7 +10,6 @@ error[E0433]: failed to resolve: use of undeclared crate or module `foo`
 LL | fn lint_files() -> impl Iterator<Item = foo::MissingItem> {
    |                                         ^^^ use of undeclared crate or module `foo`
 
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0277, E0433.
-For more information about an error, try `rustc --explain E0277`.
+For more information about this error, try `rustc --explain E0433`.

Diff for: tests/crashes/127266.rs

@@ -9,7 +9,6 @@ impl<T, S: Iterator<Item = T>> Iterator for ChunkingIterator<T, S> {
     type Item = IteratorChunk<T, S>; //~ ERROR missing lifetime
 
     fn next(&mut self) -> Option<IteratorChunk<T, S>> {
-        //~^ ERROR `impl` item signature doesn't match `trait` item signature
         todo!()
     }
 }

Diff for: tests/crashes/127304.rs

@@ -9,20 +9,6 @@ help: consider introducing a named lifetime parameter
 LL |     type Item<'a> = IteratorChunk<'a, T, S>;
    |              ++++                 +++
 
-error: `impl` item signature doesn't match `trait` item signature
-  --> $DIR/issue-74918-missing-lifetime.rs:11:5
-   |
-LL |     fn next(&mut self) -> Option<IteratorChunk<T, S>> {
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ found `fn(&'1 mut ChunkingIterator<T, S>) -> Option<IteratorChunk<'1, T, S>>`
-  --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
-   |
-   = note: expected `fn(&'1 mut ChunkingIterator<T, S>) -> Option<IteratorChunk<'2, T, S>>`
-   |
-   = note: expected signature `fn(&'1 mut ChunkingIterator<T, S>) -> Option<IteratorChunk<'2, T, S>>`
-              found signature `fn(&'1 mut ChunkingIterator<T, S>) -> Option<IteratorChunk<'1, T, S>>`
-   = help: the lifetime requirements from the `impl` do not correspond to the requirements in the `trait`
-   = help: verify the lifetime relationships in the `trait` and `impl` between the `self` argument, the other inputs and its output
-
-error: aborting due to 2 previous errors
+error: aborting due to 1 previous error
 
 For more information about this error, try `rustc --explain E0106`.

Diff for: tests/rustdoc-ui/unable-fulfill-trait.rs

@@ -0,0 +1,9 @@
+//! This test checks that we taint typeck results when there are
+//! error lifetimes, even though typeck doesn't actually care about lifetimes.
+
+struct Slice(&'reborrow [&'static [u8]]);
+//~^ ERROR undeclared lifetime
+
+static MAP: Slice = Slice(&[b"" as &'static [u8]]);
+
+fn main() {}

Diff for: tests/rustdoc-ui/unable-fulfill-trait.stderr

@@ -0,0 +1,11 @@
+error[E0261]: use of undeclared lifetime name `'reborrow`
+  --> $DIR/missing_lifetime.rs:4:15
+   |
+LL | struct Slice(&'reborrow [&'static [u8]]);
+   |             - ^^^^^^^^^ undeclared lifetime
+   |             |
+   |             help: consider introducing lifetime `'reborrow` here: `<'reborrow>`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0261`.