https://gcc.gnu.org/g:2992ff08f68e7b9bb36cdeb6747cdc1ee9015d54

commit r15-8523-g2992ff08f68e7b9bb36cdeb6747cdc1ee9015d54
Author: Philip Herron <herron.phi...@googlemail.com>
Date:   Tue Nov 12 12:16:40 2024 +0000

    gccrs: Fix bad handling for recursive type query
    
    When resolving a type like this which is generic it causes the argument
    substitution to go through bounds checking which is expected. But this
    can call a type bounds probe which again calls a type query which will be
    on the Impl Type on an impl block which can result in a recursive type
    query which does eventually get caught and errors correctly. But this then
    triggers some old error diagnositcs which are not valid error codes but old
    error messages we used to catch simple errors very early on which do not
    apply for this senario.
    
    Fixes Rust-GCC#2905
    
    gcc/rust/ChangeLog:
    
            * typecheck/rust-hir-type-check-item.cc 
(TypeCheckItem::resolve_impl_block_substitutions):
            dont check for unconstrained when the self is not resolved
            * typecheck/rust-hir-type-check-type.cc 
(TypeCheckType::resolve_root_path):
            remove bad debug error diagnostic
            * typecheck/rust-tyty-subst.cc: likewise
    
    gcc/testsuite/ChangeLog:
    
            * rust/compile/nr2/exclude: nr2 cant handle this
            * rust/compile/issue-2905-1.rs: New test.
            * rust/compile/issue-2905-2.rs: New test.
    
    Signed-off-by: Philip Herron <herron.phi...@googlemail.com>

Diff:
---
 gcc/rust/typecheck/rust-hir-type-check-item.cc |   8 ++
 gcc/rust/typecheck/rust-hir-type-check-type.cc |   7 +-
 gcc/rust/typecheck/rust-tyty-subst.cc          |   3 -
 gcc/testsuite/rust/compile/issue-2905-1.rs     |  27 +++++
 gcc/testsuite/rust/compile/issue-2905-2.rs     | 136 +++++++++++++++++++++++++
 gcc/testsuite/rust/compile/nr2/exclude         |   2 +
 6 files changed, 175 insertions(+), 8 deletions(-)

diff --git a/gcc/rust/typecheck/rust-hir-type-check-item.cc 
b/gcc/rust/typecheck/rust-hir-type-check-item.cc
index 28368d4730a4..0652777c8c62 100644
--- a/gcc/rust/typecheck/rust-hir-type-check-item.cc
+++ b/gcc/rust/typecheck/rust-hir-type-check-item.cc
@@ -724,6 +724,14 @@ TypeCheckItem::resolve_impl_block_substitutions 
(HIR::ImplBlock &impl_block,
     }
 
   TyTy::BaseType *self = TypeCheckType::Resolve (impl_block.get_type ().get 
());
+  if (self->is<TyTy::ErrorType> ())
+    {
+      // we cannot check for unconstrained type arguments when the Self type is
+      // not resolved it will just add extra errors that dont help as well as
+      // the case where this could just be a recursive type query that should
+      // fail and will work later on anyway
+      return {substitutions, region_constraints};
+    }
 
   // inherit the bounds
   if (!specified_bound.is_error ())
diff --git a/gcc/rust/typecheck/rust-hir-type-check-type.cc 
b/gcc/rust/typecheck/rust-hir-type-check-type.cc
index ee17e53eb306..0ff4ac45247a 100644
--- a/gcc/rust/typecheck/rust-hir-type-check-type.cc
+++ b/gcc/rust/typecheck/rust-hir-type-check-type.cc
@@ -426,11 +426,8 @@ TypeCheckType::resolve_root_path (HIR::TypePath &path, 
size_t *offset,
       if (!query_type (ref, &lookup))
        {
          if (is_root)
-           {
-             rust_error_at (seg->get_locus (),
-                            "failed to resolve root segment");
-             return new TyTy::ErrorType (path.get_mappings ().get_hirid ());
-           }
+           return new TyTy::ErrorType (path.get_mappings ().get_hirid ());
+
          return root_tyty;
        }
 
diff --git a/gcc/rust/typecheck/rust-tyty-subst.cc 
b/gcc/rust/typecheck/rust-tyty-subst.cc
index a3ebf0aa8d55..575f04a3030c 100644
--- a/gcc/rust/typecheck/rust-tyty-subst.cc
+++ b/gcc/rust/typecheck/rust-tyty-subst.cc
@@ -634,8 +634,6 @@ SubstitutionRef::get_mappings_from_generic_args (
              if (resolved == nullptr
                  || resolved->get_kind () == TyTy::TypeKind::ERROR)
                {
-                 rust_error_at (binding.get_locus (),
-                                "failed to resolve type arguments");
                  return SubstitutionArgumentMappings::error ();
                }
 
@@ -701,7 +699,6 @@ SubstitutionRef::get_mappings_from_generic_args (
       BaseType *resolved = Resolver::TypeCheckType::Resolve (arg.get ());
       if (resolved == nullptr || resolved->get_kind () == 
TyTy::TypeKind::ERROR)
        {
-         rust_error_at (args.get_locus (), "failed to resolve type arguments");
          return SubstitutionArgumentMappings::error ();
        }
 
diff --git a/gcc/testsuite/rust/compile/issue-2905-1.rs 
b/gcc/testsuite/rust/compile/issue-2905-1.rs
new file mode 100644
index 000000000000..9b0c19da9bb5
--- /dev/null
+++ b/gcc/testsuite/rust/compile/issue-2905-1.rs
@@ -0,0 +1,27 @@
+#![feature(lang_items)]
+
+#[lang = "sized"]
+trait Sized {}
+
+pub struct A<T>(T);
+
+pub trait B {
+    type C;
+}
+
+// ------
+// swap these two items
+
+impl B for i32 {
+    type C = Weird<i32>;
+}
+
+pub struct Weird<T>(A<(T,)>);
+
+// ------
+
+trait Foo {}
+
+impl Foo for Weird<i32> {}
+
+fn main() {}
diff --git a/gcc/testsuite/rust/compile/issue-2905-2.rs 
b/gcc/testsuite/rust/compile/issue-2905-2.rs
new file mode 100644
index 000000000000..83c54ed92e5f
--- /dev/null
+++ b/gcc/testsuite/rust/compile/issue-2905-2.rs
@@ -0,0 +1,136 @@
+// { dg-options "-w" }
+#![feature(intrinsics)]
+#![feature(lang_items)]
+
+#[lang = "sized"]
+trait Sized {}
+
+extern "rust-intrinsic" {
+    fn transmute<T, U>(_: T) -> U;
+    fn offset<T>(src: *const T, offset: isize) -> *const T;
+}
+
+pub mod core {
+    pub mod marker {
+        #[lang = "phantom_data"]
+        pub struct PhantomData<T>;
+    }
+
+    pub mod slice {
+        use core::marker::PhantomData;
+        use core::option::Option;
+
+        impl<T> core::iter::IntoIterator for &[T] {
+            type Item = &T;
+            type IntoIter = Weird<T>;
+
+            fn into_iter(self) -> Weird<T> {
+                self.iter()
+            }
+        }
+
+        pub struct Weird<T> {
+            ptr: *const T, // should be NonNull<T> but here it does not matter
+            end: *const T,
+            _marker: PhantomData<&T>,
+        }
+
+        impl<T> Weird<T> {
+            pub(super) fn new(slice: &[T]) -> Self {
+                let ptr = slice.as_ptr();
+                // SAFETY: Similar to `IterMut::new`.
+                unsafe {
+                    // should be: ptr.add(slice.len())
+                    let end = transmute::<*const T, usize>(ptr) + slice.len(); 
// TODO(Arthur): Missing `* size_of::<T>()`?
+                    let end = transmute::<usize, *const T>(end);
+
+                    Self {
+                        ptr,
+                        end,
+                        _marker: PhantomData,
+                    }
+                }
+            }
+
+            fn is_empty(&self) -> bool {
+                self.ptr == self.end
+            }
+
+            fn next_unchecked(&mut self) -> *const T {
+                let old = self.ptr;
+
+                self.ptr = unsafe { offset(self.ptr, 1) };
+
+                old
+            }
+        }
+
+        trait Foo {}
+
+        impl<T> Foo for Weird<T> {}
+
+        // impl<T> core::iter::Iterator for Iter<T> {
+        //     type Item = &T;
+
+        //     fn next(&mut self) -> Option<&T> {
+        //         if self.is_empty() {
+        //             Option::None
+        //         } else {
+        //             Option::Some(&*self.next_unchecked())
+        //         }
+        //     }
+        // }
+
+        union Repr<T> {
+            pub(crate) rust: *const [T],
+            rust_mut: *mut [T],
+            pub(crate) raw: FatPtr<T>,
+        }
+
+        struct FatPtr<T> {
+            data: *const T,
+            pub(crate) len: usize,
+        }
+
+        impl<T> [T] {
+            pub fn iter(&self) -> Weird<T> {
+                Weird::new(self)
+            }
+
+            pub fn as_ptr(&self) -> *const T {
+                self as *const [T] as *const T
+            }
+
+            pub fn len(&self) -> usize {
+                unsafe { Repr { rust: self }.raw.len }
+            }
+        }
+    }
+
+    pub mod iter {
+        use option::Option;
+
+        pub trait IntoIterator {
+            type Item;
+
+            type IntoIter: Iterator<Item = Self::Item>;
+
+            fn into_iter(self) -> Self::IntoIter;
+        }
+
+        pub trait Iterator {
+            type Item;
+
+            fn next(&mut self) -> Option<Self::Item>;
+        }
+    }
+
+    pub mod option {
+        pub enum Option<T> {
+            Some(T),
+            None,
+        }
+    }
+}
+
+fn main() {}
diff --git a/gcc/testsuite/rust/compile/nr2/exclude 
b/gcc/testsuite/rust/compile/nr2/exclude
index efee0fd1e2dd..a73b1f027b1d 100644
--- a/gcc/testsuite/rust/compile/nr2/exclude
+++ b/gcc/testsuite/rust/compile/nr2/exclude
@@ -217,4 +217,6 @@ issue-2323.rs
 issue-2953-1.rs
 issue-2953-2.rs
 issue-1773.rs
+issue-2905-1.rs
+issue-2905-2.rs
 # please don't delete the trailing newline

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