Auto merge of rust-lang#108138 - compiler-errors:malformed-fn-trait, …

…r=TaKO8Ki Move `Fn*` traits malformedness protections to typeck I found it strange that we were doing a custom well-formedness check just for the `Fn*` traits' `call_*` fn items. My understanding from the git history is that this is just to avoid ICEs later on in typeck. Well, that well-formedness check isn't even implemented correctly for `FnOnce::call_once`, or `FnMut::call_mut` for that matter. Instead, this PR just makes the typeck checks more robust, and leaves it up to the call-site to report errors when lang items are implemented in funny ways. This coincidentally fixes another ICE where a the `Add` lang item is implemented with a `add` item that's a const instead of a method.
tharunsuresh-code · Feb 21, 2023 · 3200982 · 3200982
2 parents bda32a4 2a700d4
commit 3200982
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Showing 16 changed files with 221 additions and 74 deletions.
diff --git a/compiler/rustc_hir_analysis/src/check/wfcheck.rs b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
@@ -16,7 16,7 @@ use rustc_middle::mir::ConstraintCategory;
 use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::trait_def::TraitSpecializationKind;
 use rustc_middle::ty::{
- self, ir::TypeVisitor, AdtKind, DefIdTree, GenericParamDefKind, Ty, TyCtxt, TypeFoldable,
  self, ir::TypeVisitor, AdtKind, GenericParamDefKind, Ty, TyCtxt, TypeFoldable,
  TypeSuperVisitable,
 };
 use rustc_middle::ty::{GenericArgKind, InternalSubsts};
@@ -277,56 277,6 @@ fn check_trait_item(tcx: TyCtxt<'_>, trait_item: &hir::TraitItem<'_>) {
  };
  check_object_unsafe_self_trait_by_name(tcx, trait_item);
  check_associated_item(tcx, def_id, span, method_sig);
-
- let encl_trait_def_id = tcx.local_parent(def_id);
- let encl_trait = tcx.hir().expect_item(encl_trait_def_id);
- let encl_trait_def_id = encl_trait.owner_id.to_def_id();
- let fn_lang_item_name = if Some(encl_trait_def_id) == tcx.lang_items().fn_trait() {
- Some("fn")
- } else if Some(encl_trait_def_id) == tcx.lang_items().fn_mut_trait() {
- Some("fn_mut")
- } else {
- None
- };
-
- if let (Some(fn_lang_item_name), "call") =
- (fn_lang_item_name, trait_item.ident.name.to_ident_string().as_str())
- {
- // We are looking at the `call` function of the `fn` or `fn_mut` lang item.
- // Do some rudimentary sanity checking to avoid an ICE later (issue #83471).
- if let Some(hir::FnSig { decl, span, .. }) = method_sig {
- if let [self_ty, _] = decl.inputs {
- if !matches!(self_ty.kind, hir::TyKind::Ref(_, _)) {
- tcx.sess
- .struct_span_err(
- self_ty.span,
- &format!(
- "first argument of `call` in `{fn_lang_item_name}` lang item must be a reference",
- ),
- )
- .emit();
- }
- } else {
- tcx.sess
- .struct_span_err(
- *span,
- &format!(
- "`call` function in `{fn_lang_item_name}` lang item takes exactly two arguments",
- ),
- )
- .emit();
- }
- } else {
- tcx.sess
- .struct_span_err(
- trait_item.span,
- &format!(
- "`call` trait item in `{fn_lang_item_name}` lang item must be a function",
- ),
- )
- .emit();
- }
- }
 }
 
 /// Require that the user writes where clauses on GATs for the implicit

diff --git a/compiler/rustc_hir_typeck/src/callee.rs b/compiler/rustc_hir_typeck/src/callee.rs
@@ -247,6 247,15 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
  adjusted_ty,
  opt_input_type.as_ref().map(slice::from_ref),
  ) {
  // Check for `self` receiver on the method, otherwise we can't use this as a `Fn*` trait.
  if !self.tcx.associated_item(ok.value.def_id).fn_has_self_parameter {
  self.tcx.sess.delay_span_bug(
  call_expr.span,
  "input to overloaded call fn is not a self receiver",
  );
  return None;
  }
 
  let method = self.register_infer_ok_obligations(ok);
  let mut autoref = None;
  if borrow {
@@ -257,7 266,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
  // caused an error elsewhere.
  self.tcx
  .sess
- .delay_span_bug(call_expr.span, "input to call/call_mut is not a ref?");
  .delay_span_bug(call_expr.span, "input to call/call_mut is not a ref");
  return None;
  };
 
@@ -271,6 280,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
  target: method.sig.inputs()[0],
  });
  }
 
  return Some((autoref, method));
  }
  }
@@ -823,7 833,7 @@ impl<'a, 'tcx> DeferredCallResolution<'tcx> {
  );
  err.help(
  "make sure the `fn`/`fn_mut`/`fn_once` lang items are defined \
- and have associated `call`/`call_mut`/`call_once` functions",
  and have correctly defined `call`/`call_mut`/`call_once` methods",
  );
  err.emit();
  }

diff --git a/compiler/rustc_hir_typeck/src/method/mod.rs b/compiler/rustc_hir_typeck/src/method/mod.rs
@@ -380,6 380,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
  );
  return None;
  };
 
  if method_item.kind != ty::AssocKind::Fn {
  self.tcx.sess.delay_span_bug(tcx.def_span(method_item.def_id), "not a method");
  return None;
  }
 
  let def_id = method_item.def_id;
  let generics = tcx.generics_of(def_id);
 

diff --git a/tests/ui/lang-items/bad-add-impl.rs b/tests/ui/lang-items/bad-add-impl.rs
@@ -0,0 1,18 @@
 #![feature(no_core)]
 #![feature(lang_items)]
 #![no_core]
 
 #[lang = "sized"]
 trait Sized {}
 
 #[lang = "add"]
 trait Add<T> {
  const add: u32 = 1u32;
 }
 
 impl Add<u32> for u32 {}
 
 fn main() {
  1u32 1u32;
  //~^ ERROR cannot add `u32` to `u32`
 }
diff --git a/tests/ui/lang-items/bad-add-impl.stderr b/tests/ui/lang-items/bad-add-impl.stderr
@@ -0,0 1,11 @@
 error[E0369]: cannot add `u32` to `u32`
  --> $DIR/bad-add-impl.rs:16:10
  |
 LL | 1u32 1u32;
  | ---- ^ ---- u32
  | |
  | u32
 
 error: aborting due to previous error
 
 For more information about this error, try `rustc --explain E0369`.
diff --git a/tests/ui/lang-items/fn-fn_mut-call-ill-formed.bad_item.stderr b/tests/ui/lang-items/fn-fn_mut-call-ill-formed.bad_item.stderr
@@ -0,0 1,18 @@
 error: failed to find an overloaded call trait for closure call
  --> $DIR/fn-fn_mut-call-ill-formed.rs:39:5
  |
 LL | a();
  | ^^^
  |
  = help: make sure the `fn`/`fn_mut`/`fn_once` lang items are defined and have correctly defined `call`/`call_mut`/`call_once` methods
 
 error: failed to find an overloaded call trait for closure call
  --> $DIR/fn-fn_mut-call-ill-formed.rs:43:5
  |
 LL | b();
  | ^^^
  |
  = help: make sure the `fn`/`fn_mut`/`fn_once` lang items are defined and have correctly defined `call`/`call_mut`/`call_once` methods
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/lang-items/fn-fn_mut-call-ill-formed.bad_sig.stderr b/tests/ui/lang-items/fn-fn_mut-call-ill-formed.bad_sig.stderr
@@ -0,0 1,18 @@
 error: failed to find an overloaded call trait for closure call
  --> $DIR/fn-fn_mut-call-ill-formed.rs:39:5
  |
 LL | a();
  | ^^^
  |
  = help: make sure the `fn`/`fn_mut`/`fn_once` lang items are defined and have correctly defined `call`/`call_mut`/`call_once` methods
 
 error: failed to find an overloaded call trait for closure call
  --> $DIR/fn-fn_mut-call-ill-formed.rs:43:5
  |
 LL | b();
  | ^^^
  |
  = help: make sure the `fn`/`fn_mut`/`fn_once` lang items are defined and have correctly defined `call`/`call_mut`/`call_once` methods
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/lang-items/fn-fn_mut-call-ill-formed.fn_bad_item.stderr b/tests/ui/lang-items/fn-fn_mut-call-ill-formed.fn_bad_item.stderr
@@ -0,0 1,18 @@
 error: failed to find an overloaded call trait for closure call
  --> $DIR/fn-fn_mut-call-ill-formed.rs:42:5
  |
 LL | a();
  | ^^^
  |
  = help: make sure the `fn`/`fn_mut`/`fn_once` lang items are defined and have correctly defined `call`/`call_mut`/`call_once` methods
 
 error: failed to find an overloaded call trait for closure call
  --> $DIR/fn-fn_mut-call-ill-formed.rs:47:5
  |
 LL | b();
  | ^^^
  |
  = help: make sure the `fn`/`fn_mut`/`fn_once` lang items are defined and have correctly defined `call`/`call_mut`/`call_once` methods
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/lang-items/fn-fn_mut-call-ill-formed.fn_bad_sig.stderr b/tests/ui/lang-items/fn-fn_mut-call-ill-formed.fn_bad_sig.stderr
@@ -0,0 1,18 @@
 error: failed to find an overloaded call trait for closure call
  --> $DIR/fn-fn_mut-call-ill-formed.rs:42:5
  |
 LL | a();
  | ^^^
  |
  = help: make sure the `fn`/`fn_mut`/`fn_once` lang items are defined and have correctly defined `call`/`call_mut`/`call_once` methods
 
 error: failed to find an overloaded call trait for closure call
  --> $DIR/fn-fn_mut-call-ill-formed.rs:47:5
  |
 LL | b();
  | ^^^
  |
  = help: make sure the `fn`/`fn_mut`/`fn_once` lang items are defined and have correctly defined `call`/`call_mut`/`call_once` methods
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/lang-items/fn-fn_mut-call-ill-formed.fn_mut_bad_item.stderr b/tests/ui/lang-items/fn-fn_mut-call-ill-formed.fn_mut_bad_item.stderr
@@ -0,0 1,18 @@
 error: failed to find an overloaded call trait for closure call
  --> $DIR/fn-fn_mut-call-ill-formed.rs:42:5
  |
 LL | a();
  | ^^^
  |
  = help: make sure the `fn`/`fn_mut`/`fn_once` lang items are defined and have correctly defined `call`/`call_mut`/`call_once` methods
 
 error: failed to find an overloaded call trait for closure call
  --> $DIR/fn-fn_mut-call-ill-formed.rs:47:5
  |
 LL | b();
  | ^^^
  |
  = help: make sure the `fn`/`fn_mut`/`fn_once` lang items are defined and have correctly defined `call`/`call_mut`/`call_once` methods
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/lang-items/fn-fn_mut-call-ill-formed.fn_mut_bad_sig.stderr b/tests/ui/lang-items/fn-fn_mut-call-ill-formed.fn_mut_bad_sig.stderr
@@ -0,0 1,18 @@
 error: failed to find an overloaded call trait for closure call
  --> $DIR/fn-fn_mut-call-ill-formed.rs:42:5
  |
 LL | a();
  | ^^^
  |
  = help: make sure the `fn`/`fn_mut`/`fn_once` lang items are defined and have correctly defined `call`/`call_mut`/`call_once` methods
 
 error: failed to find an overloaded call trait for closure call
  --> $DIR/fn-fn_mut-call-ill-formed.rs:47:5
  |
 LL | b();
  | ^^^
  |
  = help: make sure the `fn`/`fn_mut`/`fn_once` lang items are defined and have correctly defined `call`/`call_mut`/`call_once` methods
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/lang-items/fn-fn_mut-call-ill-formed.fn_once_bad_item.stderr b/tests/ui/lang-items/fn-fn_mut-call-ill-formed.fn_once_bad_item.stderr
@@ -0,0 1,18 @@
 error: failed to find an overloaded call trait for closure call
  --> $DIR/fn-fn_mut-call-ill-formed.rs:42:5
  |
 LL | a();
  | ^^^
  |
  = help: make sure the `fn`/`fn_mut`/`fn_once` lang items are defined and have correctly defined `call`/`call_mut`/`call_once` methods
 
 error: failed to find an overloaded call trait for closure call
  --> $DIR/fn-fn_mut-call-ill-formed.rs:47:5
  |
 LL | b();
  | ^^^
  |
  = help: make sure the `fn`/`fn_mut`/`fn_once` lang items are defined and have correctly defined `call`/`call_mut`/`call_once` methods
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/lang-items/fn-fn_mut-call-ill-formed.fn_once_bad_sig.stderr b/tests/ui/lang-items/fn-fn_mut-call-ill-formed.fn_once_bad_sig.stderr
@@ -0,0 1,18 @@
 error: failed to find an overloaded call trait for closure call
  --> $DIR/fn-fn_mut-call-ill-formed.rs:42:5
  |
 LL | a();
  | ^^^
  |
  = help: make sure the `fn`/`fn_mut`/`fn_once` lang items are defined and have correctly defined `call`/`call_mut`/`call_once` methods
 
 error: failed to find an overloaded call trait for closure call
  --> $DIR/fn-fn_mut-call-ill-formed.rs:47:5
  |
 LL | b();
  | ^^^
  |
  = help: make sure the `fn`/`fn_mut`/`fn_once` lang items are defined and have correctly defined `call`/`call_mut`/`call_once` methods
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/lang-items/fn-fn_mut-call-ill-formed.rs b/tests/ui/lang-items/fn-fn_mut-call-ill-formed.rs
@@ -1,27 1,49 @@
-// Make sure that an error is reported if the `call` function of the
-// `fn`/`fn_mut` lang item is grossly ill-formed.
 // revisions: fn_once_bad_item fn_once_bad_sig fn_mut_bad_item fn_mut_bad_sig fn_bad_item fn_bad_sig
 
 #![feature(lang_items)]
 #![feature(no_core)]
 #![no_core]
 
 #[lang = "sized"]
 trait Sized {}
 
 #[cfg(any(fn_bad_item, fn_bad_sig))]
 #[lang = "fn"]
 trait MyFn<T> {
  #[cfg(fn_bad_sig)]
  fn call(i: i32) -> i32 { 0 }
 
  #[cfg(fn_bad_item)]
  const call: i32 = 42;
- //~^ ERROR: `call` trait item in `fn` lang item must be a function
 }
 
 #[cfg(any(fn_mut_bad_item, fn_mut_bad_sig))]
 #[lang = "fn_mut"]
 trait MyFnMut<T> {
- fn call(i: i32, j: i32) -> i32 { i j }
- //~^ ERROR: first argument of `call` in `fn_mut` lang item must be a reference
  #[cfg(fn_mut_bad_sig)]
  fn call_mut(i: i32) -> i32 { 0 }
 
  #[cfg(fn_mut_bad_item)]
  const call_mut: i32 = 42;
 }
 
 #[cfg(any(fn_once_bad_item, fn_once_bad_sig))]
 #[lang = "fn_once"]
 trait MyFnOnce<T> {
  #[cfg(fn_once_bad_sig)]
  fn call_once(i: i32) -> i32 { 0 }
 
  #[cfg(fn_once_bad_item)]
  const call_once: i32 = 42;
 }
 
 fn main() {
  let a = || 42;
  a();
  //~^ ERROR failed to find an overloaded call trait for closure call
 
  let mut i = 0;
- let mut b = || { i = 1; };
  let mut b = || { };
  b();
  //~^ ERROR failed to find an overloaded call trait for closure call
 }
diff --git a/tests/ui/lang-items/fn-fn_mut-call-ill-formed.stderr b/tests/ui/lang-items/fn-fn_mut-call-ill-formed.stderr
diff --git a/tests/ui/lang-items/issue-86238.stderr b/tests/ui/lang-items/issue-86238.stderr
@@ -4,7 4,7 @@ error: failed to find an overloaded call trait for closure call
 LL | one()
  | ^^^^^
  |
- = help: make sure the `fn`/`fn_mut`/`fn_once` lang items are defined and have associated `call`/`call_mut`/`call_once` functions
  = help: make sure the `fn`/`fn_mut`/`fn_once` lang items are defined and have correctly defined `call`/`call_mut`/`call_once` methods
 
 error: aborting due to previous error