Auto merge of #126581 - GuillaumeGomez:rollup-dx4fadn, r=GuillaumeGomez

Rollup of 3 pull requests

Successful merges:

 - #126226 (Make suggestion to change `Fn` to `FnMut` work with methods as well)
 - #126570 (Convert a `span_bug` to a `span_delayed_bug`.)
 - #126580 (Add `run-make/const_fn_mir` missing test annotation)

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

compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs

@@ -937,24 +937,50 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
         let node = self.infcx.tcx.hir_node(fn_call_id);
         let def_id = hir.enclosing_body_owner(fn_call_id);
         let mut look_at_return = true;
-        // If we can detect the expression to be an `fn` call where the closure was an argument,
+
-        // we point at the `fn` definition argument...
+        // If the HIR node is a function or method call gets the def ID
-        if let hir::Node::Expr(hir::Expr { kind: hir::ExprKind::Call(func, args), .. }) = node {
+        // of the called function or method and the span and args of the call expr
-            let arg_pos = args
+        let get_call_details = || {
+            let hir::Node::Expr(hir::Expr { hir_id, kind, .. }) = node else {
+                return None;
+            };
+
+            let typeck_results = self.infcx.tcx.typeck(def_id);
+
+            match kind {
+                hir::ExprKind::Call(expr, args) => {
+                    if let Some(ty::FnDef(def_id, _)) =
+                        typeck_results.node_type_opt(expr.hir_id).as_ref().map(|ty| ty.kind())
+                    {
+                        Some((*def_id, expr.span, *args))
+                    } else {
+                        None
+                    }
+                }
+                hir::ExprKind::MethodCall(_, _, args, span) => {
+                    if let Some(def_id) = typeck_results.type_dependent_def_id(*hir_id) {
+                        Some((def_id, *span, *args))
+                    } else {
+                        None
+                    }
+                }
+                _ => None,
+            }
+        };
+
+        // If we can detect the expression to be an function or method call where the closure was an argument,
+        // we point at the function or method definition argument...
+        if let Some((callee_def_id, call_span, call_args)) = get_call_details() {
+            let arg_pos = call_args
                 .iter()
                 .enumerate()
                 .filter(|(_, arg)| arg.hir_id == closure_id)
                 .map(|(pos, _)| pos)
                 .next();
-            let tables = self.infcx.tcx.typeck(def_id);
+
-            if let Some(ty::FnDef(def_id, _)) =
+            let arg = match hir.get_if_local(callee_def_id) {
-                tables.node_type_opt(func.hir_id).as_ref().map(|ty| ty.kind())
-            {
-                let arg = match hir.get_if_local(*def_id) {
                 Some(
-                        hir::Node::Item(hir::Item {
+                    hir::Node::Item(hir::Item { ident, kind: hir::ItemKind::Fn(sig, ..), .. })
-                            ident, kind: hir::ItemKind::Fn(sig, ..), ..
-                        })
                     | hir::Node::TraitItem(hir::TraitItem {
                         ident,
                         kind: hir::TraitItemKind::Fn(sig, _),
@@ -983,12 +1009,11 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
             };
             if let Some(span) = arg {
                 err.span_label(span, "change this to accept `FnMut` instead of `Fn`");
-                    err.span_label(func.span, "expects `Fn` instead of `FnMut`");
+                err.span_label(call_span, "expects `Fn` instead of `FnMut`");
                 err.span_label(closure_span, "in this closure");
                 look_at_return = false;
             }
         }
-        }
 
         if look_at_return && hir.get_fn_id_for_return_block(closure_id).is_some() {
             // ...otherwise we are probably in the tail expression of the function, point at the

compiler/rustc_borrowck/src/diagnostics/region_name.rs

@@ -628,9 +628,7 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
                     | GenericArgKind::Const(_),
                     _,
                 ) => {
-                    // This was previously a `span_delayed_bug` and could be
+                    self.dcx().span_delayed_bug(
-                    // reached by the test for #82126, but no longer.
-                    self.dcx().span_bug(
                         hir_arg.span(),
                         format!("unmatched arg and hir arg: found {kind:?} vs {hir_arg:?}"),
                     );

tests/crashes/126385.rs

@@ -1,10 +0,0 @@
-//@ known-bug: rust-lang/rust#126385
-pub struct MyStruct<'field> {
-    field: &'_ [u32],
-}
-
-impl MyStruct<'_> {
-    pub fn _<'a>(field: &'a[u32]) -> Self<new> {
-    Self{field}
-    }
-}

tests/run-make/const_fn_mir/rmake.rs

@@ -1,5 +1,7 @@
 // The `needs-unwind -Cpanic=abort` gives a different MIR output.
 
+//@ needs-unwind
+
 use run_make_support::{cwd, diff, rustc};
 
 fn main() {

tests/ui/borrowck/unmatched-arg-and-hir-arg-issue-126385.rs

@@ -0,0 +1,14 @@
+// This test was triggering a `span_bug` crash, which was then fixed by
+// downgrading it to a `span_delayed_bug`.
+
+pub struct MyStruct<'field> {
+    field: &'field [u32],
+}
+
+impl MyStruct<'_> {
+    pub fn f(field: &[u32]) -> Self<u32> { //~ ERROR type arguments are not allowed on self type
+        Self { field }                     //~ ERROR lifetime may not live long enough
+    }
+}
+
+fn main() {}

tests/ui/borrowck/unmatched-arg-and-hir-arg-issue-126385.stderr

@@ -0,0 +1,34 @@
+error[E0109]: type arguments are not allowed on self type
+  --> $DIR/unmatched-arg-and-hir-arg-issue-126385.rs:9:37
+   |
+LL |     pub fn f(field: &[u32]) -> Self<u32> {
+   |                                ---- ^^^ type argument not allowed
+   |                                |
+   |                                not allowed on self type
+   |
+note: `Self` is of type `MyStruct<'_>`
+  --> $DIR/unmatched-arg-and-hir-arg-issue-126385.rs:4:12
+   |
+LL | pub struct MyStruct<'field> {
+   |            ^^^^^^^^ `Self` corresponds to this type
+...
+LL | impl MyStruct<'_> {
+   | ----------------- `Self` is on type `MyStruct` in this `impl`
+help: the `Self` type doesn't accept type parameters, use the concrete type's name `MyStruct` instead if you want to specify its type parameters
+   |
+LL |     pub fn f(field: &[u32]) -> MyStruct<u32> {
+   |                                ~~~~~~~~
+
+error: lifetime may not live long enough
+  --> $DIR/unmatched-arg-and-hir-arg-issue-126385.rs:10:9
+   |
+LL |     pub fn f(field: &[u32]) -> Self<u32> {
+   |                     -          --------- return type is MyStruct<'2>
+   |                     |
+   |                     let's call the lifetime of this reference `'1`
+LL |         Self { field }
+   |         ^^^^^^^^^^^^^^ associated function was supposed to return data with lifetime `'2` but it is returning data with lifetime `'1`
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0109`.

tests/ui/closures/wrong-closure-arg-suggestion-125325.rs

@@ -0,0 +1,29 @@
+// Regression test for #125325
+
+// Tests that we suggest changing an `impl Fn` param
+// to `impl FnMut` when the provided closure arg
+// is trying to mutate the closure env.
+// Ensures that it works that way for both
+// functions and methods
+
+struct S;
+
+impl S {
+    fn assoc_func(&self, _f: impl Fn()) -> usize {
+        0
+    }
+}
+
+fn func(_f: impl Fn()) -> usize {
+    0
+}
+
+fn test_func(s: &S) -> usize {
+    let mut x = ();
+    s.assoc_func(|| x = ());
+    //~^ cannot assign to `x`, as it is a captured variable in a `Fn` closure
+    func(|| x = ())
+    //~^ cannot assign to `x`, as it is a captured variable in a `Fn` closure
+}
+
+fn main() {}

tests/ui/closures/wrong-closure-arg-suggestion-125325.stderr

@@ -0,0 +1,28 @@
+error[E0594]: cannot assign to `x`, as it is a captured variable in a `Fn` closure
+  --> $DIR/wrong-closure-arg-suggestion-125325.rs:23:21
+   |
+LL |     fn assoc_func(&self, _f: impl Fn()) -> usize {
+   |                              --------- change this to accept `FnMut` instead of `Fn`
+...
+LL |     s.assoc_func(|| x = ());
+   |       --------------^^^^^^-
+   |       |          |  |
+   |       |          |  cannot assign
+   |       |          in this closure
+   |       expects `Fn` instead of `FnMut`
+
+error[E0594]: cannot assign to `x`, as it is a captured variable in a `Fn` closure
+  --> $DIR/wrong-closure-arg-suggestion-125325.rs:25:13
+   |
+LL | fn func(_f: impl Fn()) -> usize {
+   |             --------- change this to accept `FnMut` instead of `Fn`
+...
+LL |     func(|| x = ())
+   |     ---- -- ^^^^^^ cannot assign
+   |     |    |
+   |     |    in this closure
+   |     expects `Fn` instead of `FnMut`
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0594`.