Merge #358

358: Canonical Paths for Name Resolution and handle TurboFish properly r=philberty a=philberty

Add Canonical paths to name resolution
    
In order to support name resolution and checks for duplicate definitions
of names we need canonical paths for all DefId items such as inherent impl
items and normal items. Consider:

```rust
  struct Foo<T>(T);

  impl Foo<f32> {
    fn name()...
  }

  impl Foo<i32> {
    fn name()...
  }
```

Each of the impl blocks have a name function but these are separate due to
the concrete impl of the Parameter type passed in.

The caveat here is that to call this Function name the programmer must be
explicit in which implentation they wish to call such as:

```rust
  let a = Foo::<f32>::name();
```

This lets the Path probe lookup the appropriate impl block. The problem here
is that rust also allows for the compiler to infer the impl you wish such
as:

```rust
  let a = Foo::name();
```

This should fail since there are multiple candidates possible for this
Path. Unless there might have only been one name function in which case
it would have worked.

This patch is also responsible to implement PathInExpression by iterating
each segment and applying generic arguments as we go.

Fixes #355 #335 #325 #353


Co-authored-by: Philip Herron <philip.herron@embecosm.com>

2 files changed, 3 insertions, 3 deletions

diff --git a/gcc/rust/backend/rust-compile-expr.h b/gcc/rust/backend/rust-compile-expr.h
index d0c752c..f98ebc6 100644
--- a/gcc/rust/backend/rust-compile-expr.h
+++ b/gcc/rust/backend/rust-compile-expr.h
@@ -526,7 +526,7 @@ public:
 
   void visit (HIR::PathInExpression &expr) override
   {
-    translated = ResolvePathRef::Compile (&expr, ctx);
+    translated = ResolvePathRef::Compile (expr, ctx);
   }
 
   void visit (HIR::LoopExpr &expr) override
diff --git a/gcc/rust/backend/rust-compile-resolve-path.h b/gcc/rust/backend/rust-compile-resolve-path.h
index da1d97e..30486d0 100644
--- a/gcc/rust/backend/rust-compile-resolve-path.h
+++ b/gcc/rust/backend/rust-compile-resolve-path.h
@@ -30,10 +30,10 @@ class ResolvePathRef : public HIRCompileBase
   using Rust::Compile::HIRCompileBase::visit;
 
 public:
-  static Bexpression *Compile (HIR::Expr *expr, Context *ctx)
+  static Bexpression *Compile (HIR::PathInExpression &expr, Context *ctx)
   {
     ResolvePathRef resolver (ctx);
-    expr->accept_vis (resolver);
+    expr.accept_vis (resolver);
     return resolver.resolved;
   }