gccrs: make predicate bounds overwrite-able

When compiling types especially when using queries it needs to be
permissive and allow them to be overwritten and a predicate might have one
set of details in one senario and a new one with the same id later on but
with different types.

Fixes #1524

Signed-off-by: Philip Herron <herron.philip@googlemail.com>

gcc/rust/ChangeLog:

	* typecheck/rust-typecheck-context.cc (TypeCheckContext::insert_resolved_predicate): remove

gcc/testsuite/ChangeLog:

	* rust/compile/issue-1524.rs: New test.

2 files changed, 51 insertions, 2 deletions

diff --git a/gcc/rust/typecheck/rust-typecheck-context.cc b/gcc/rust/typecheck/rust-typecheck-context.cc
index 096ce26..6bc4160 100644
--- a/gcc/rust/typecheck/rust-typecheck-context.cc
+++ b/gcc/rust/typecheck/rust-typecheck-context.cc
@@ -437,8 +437,8 @@ void
 TypeCheckContext::insert_resolved_predicate (HirId id,
 					     TyTy::TypeBoundPredicate predicate)
 {
-  auto it = predicates.find (id);
-  rust_assert (it == predicates.end ());
+  // auto it = predicates.find (id);
+  // rust_assert (it == predicates.end ());
 
   predicates.insert ({id, predicate});
 }
diff --git a/gcc/testsuite/rust/compile/issue-1524.rs b/gcc/testsuite/rust/compile/issue-1524.rs
new file mode 100644
index 0000000..e46efe4
--- /dev/null
+++ b/gcc/testsuite/rust/compile/issue-1524.rs
@@ -0,0 +1,49 @@
+// { dg-additional-options "-w" }
+// https://github.com/Rust-GCC/gccrs/issues/1524
+// https://github.com/rust-lang/rust/blob/673d0db5e393e9c64897005b470bfeb6d5aec61b/src/test/ui/methods/method-normalize-bounds-issue-20604.rs
+trait Hasher {
+    type Output;
+    fn finish(&self) -> Self::Output;
+}
+
+trait Hash<H: Hasher> {
+    fn hash(&self, h: &mut H);
+}
+
+trait HashState {
+    type Wut: Hasher;
+    fn hasher(&self) -> Self::Wut;
+}
+
+struct SipHasher;
+impl Hasher for SipHasher {
+    type Output = u64;
+    fn finish(&self) -> u64 { 4 }
+}
+
+impl Hash<SipHasher> for isize {
+    fn hash(&self, h: &mut SipHasher) {}
+}
+
+struct SipState;
+impl HashState for SipState {
+    type Wut = SipHasher;
+    fn hasher(&self) -> SipHasher { SipHasher }
+}
+
+struct Map<S> {
+    s: S,
+}
+
+impl<S> Map<S>
+    where S: HashState,
+          <S as HashState>::Wut: Hasher<Output=u64>,
+{
+    fn foo<K>(&self, k: K) where K: Hash< <S as HashState>::Wut> {}
+}
+
+fn foo<K: Hash<SipHasher>>(map: &Map<SipState>) {
+    map.foo(22);
+}
+
+fn main() {}