Account for more cases

Author: estebank

compiler/rustc_borrowck/src/diagnostics/region_errors.rs

@@ -499,7 +499,11 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
             }
         };
 
-        self.explain_impl_static_obligation(&mut diag, cause.code(), outlived_fr);
+        if let ConstraintCategory::CallArgument(Some(ty)) = category {
+            self.explain_impl_static_obligation(&mut diag, ty, cause.span, outlived_fr);
+        } else if let ObligationCauseCode::MethodCallConstraint(ty, call_span) = cause.code() {
+            self.explain_impl_static_obligation(&mut diag, *ty, *call_span, outlived_fr);
+        }
 
         match variance_info {
             ty::VarianceDiagInfo::None => {}
@@ -621,14 +625,11 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
     fn explain_impl_static_obligation(
         &self,
         diag: &mut Diag<'_>,
-        code: &ObligationCauseCode<'tcx>,
+        ty: Ty<'tcx>,
+        call_span: Span,
         outlived_fr: RegionVid,
     ) {
         let tcx = self.infcx.tcx;
-        debug!(?code);
-        let ObligationCauseCode::MethodCallConstraint(ty, call_span) = code else {
-            return;
-        };
         let ty::FnDef(def_id, args) = ty.kind() else {
             return;
         };
@@ -722,7 +723,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
         if let ty::Ref(region, _, _) = self
             .infcx
             .instantiate_binder_with_fresh_vars(
-                *call_span,
+                call_span,
                 BoundRegionConversionTime::FnCall,
                 tcx.fn_sig(def_id).instantiate_identity().inputs().map_bound(|inputs| inputs[0]),
             )
@@ -804,10 +805,10 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
             let span: MultiSpan = predicates.into();
             diag.span_note(span, format!("the `impl` on `{ty}` has {a_static_lt}"));
         }
-        if new_primary_span && diag.span.primary_span() != Some(*call_span) {
-            diag.replace_span_with(*call_span, false);
+        if new_primary_span && diag.span.primary_span() != Some(call_span) {
+            diag.replace_span_with(call_span, false);
             diag.span_label(
-                *call_span,
+                call_span,
                 "calling this method introduces a `'static` lifetime requirement",
             );
         }

tests/ui/lifetimes/dyn-trait-static-obligation.rs

@@ -0,0 +1,47 @@
+use std::cell::*;
+
+#[derive(Default)]
+struct Test {
+    pub foo: u32,
+}
+
+trait FooSetter {
+    fn set_foo(&mut self, value: u32);
+}
+
+impl FooSetter for Test {
+    fn set_foo(&mut self, value: u32) {
+        self.foo = value;
+    }
+}
+
+trait BaseSetter{
+    fn set(&mut self, value: u32);
+}
+impl BaseSetter for dyn FooSetter {
+    fn set(&mut self, value: u32){
+        self.set_foo(value);
+    }
+}
+
+struct TestHolder<'a> {
+    pub holder: Option<RefCell<&'a mut dyn FooSetter>>,
+}
+
+impl <'a>TestHolder<'a>{
+    pub fn test_foo(&self){
+       self.holder.as_ref().unwrap().borrow_mut().set(20);
+       //~^ ERROR borrowed data escapes outside of method
+    }
+}
+
+fn main() {
+    let mut test = Test::default();
+    test.foo = 10;
+    {
+        let holder = TestHolder { holder: Some(RefCell::from(&mut test))};
+
+        holder.test_foo();
+    }
+    test.foo = 30;
+}

tests/ui/lifetimes/dyn-trait-static-obligation.stderr

@@ -0,0 +1,24 @@
+error[E0521]: borrowed data escapes outside of method
+  --> $DIR/dyn-trait-static-obligation.rs:33:8
+   |
+LL | impl <'a>TestHolder<'a>{
+   |       -- lifetime `'a` defined here
+LL |     pub fn test_foo(&self){
+   |                     ----- `self` is a reference that is only valid in the method body
+LL |        self.holder.as_ref().unwrap().borrow_mut().set(20);
+   |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |        |
+   |        `self` escapes the method body here
+   |        argument requires that `'a` must outlive `'static`
+   |
+   = note: requirement occurs because of a mutable reference to `dyn FooSetter`
+   = note: mutable references are invariant over their type parameter
+   = help: see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance
+help: consider relaxing the implicit `'static` requirement on the impl
+   |
+LL | impl BaseSetter for dyn FooSetter + '_ {
+   |                                   ++++
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0521`.