Fixed available generic args for default impls, and lowering diagnost…

…ics of trait fn bodies.

Fixes #7031
Fixes #7038

commit-id:c29f1286

crates/cairo-lang-lowering/src/db.rs

@@ -732,7 +732,16 @@ fn module_lowering_diagnostics(
             ModuleItemId::Enum(_) => {}
             ModuleItemId::TypeAlias(_) => {}
             ModuleItemId::ImplAlias(_) => {}
-            ModuleItemId::Trait(_) => {}
+            ModuleItemId::Trait(trait_id) => {
+                for trait_func in db.trait_functions(*trait_id)?.values() {
+                    if matches!(db.trait_function_body(*trait_func), Ok(Some(_))) {
+                        let function_id = defs::ids::FunctionWithBodyId::Trait(*trait_func);
+                        diagnostics.extend(
+                            db.semantic_function_with_body_lowering_diagnostics(function_id)?,
+                        );
+                    }
+                }
+            }
             ModuleItemId::Impl(impl_def_id) => {
                 for impl_func in db.impl_functions(*impl_def_id)?.values() {
                     let function_id = defs::ids::FunctionWithBodyId::Impl(*impl_func);

crates/cairo-lang-semantic/src/items/trt.rs

@@ -1355,7 +1355,7 @@ pub fn priv_trait_function_body_data(
     // Compute declaration semantic.
     let trait_function_declaration_data =
         db.priv_trait_function_declaration_data(trait_function_id)?;
-    let parent_resolver_data = db.trait_resolver_data(trait_id)?;
+    let parent_resolver_data = trait_function_declaration_data.resolver_data;
     let inference_id = InferenceId::LookupItemDefinition(LookupItemId::TraitItem(
         TraitItemId::Function(trait_function_id),
     ));

tests/bug_samples/issue7031.cairo

@@ -0,0 +1,25 @@
+pub trait IteratorEx<T, impl I: Iterator<T>, +Destruct<T>, +Drop<I::Item>> {
+    fn advance_by(
+        ref self: T, n: usize,
+    ) -> Result<
+        (), NonZero<usize>,
+    > {
+        let mut res = Result::Ok(());
+        for i in 0..n {
+            if self.next().is_none() {
+                res = Result::Err((n - i).try_into().unwrap());
+                break;
+            }
+        };
+        res
+    }
+}
+impl ItratorExImpl<T, impl I: Iterator<T>, +Destruct<T>, +Drop<I::Item>> of IteratorEx<T, I> {}
+
+#[test]
+fn test_advance_by() {
+    let mut iter = array![1_u8, 2, 3, 4].into_iter();
+    assert_eq!(iter.advance_by(2), Result::Ok(()));
+    assert_eq!(iter.next(), Option::Some(3));
+    assert_eq!(iter.advance_by(0), Result::Ok(()));
+}

tests/bug_samples/issue7038.cairo

@@ -0,0 +1,5 @@
+trait DefaultTraitImpl {
+    fn call<T, F, +Drop<F>, impl func: core::ops::FnOnce<F, ()>[Output: T], +Drop<T>>(f: F) {
+        f();
+    }
+}

tests/bug_samples/lib.cairo

@@ -53,6 +53,8 @@ mod issue6623;
 mod issue6755;
 mod issue6920;
 mod issue6968;
+mod issue7031;
+mod issue7038;
 mod loop_break_in_match;
 mod loop_only_change;
 mod partial_param_local;