[gcc/devel/rust/master] Fix generic param redefined bug

[gcc/devel/rust/master] Fix generic param redefined bug

[Thomas Schwinge]

https://gcc.gnu.org/g:0d4fc557c7f1e8e645354d7e40b955a7a03b52d0

commit 0d4fc557c7f1e8e645354d7e40b955a7a03b52d0
Author: Philip Herron <philip.herron@embecosm.com>
Date:   Thu Apr 21 18:57:24 2022 +0100

    Fix generic param redefined bug
    
    When we name-resolve generic parameters their declaration gets inserted in
    to the upper-most rib on the stack. Then when this is referenced we lookup
    the relevant binding starting from the uppermost rib this lead to the 2nd
    extern item adding the same binding into the same rib which caused this
    clash. To fix this we need to have a seperate rib for each declaration
    so as reusing the same names don't clash with each other.
    
    Fixes #1131

Diff:
---
 gcc/rust/resolve/rust-ast-resolve-item.h | 14 ++++++++++++++
 gcc/testsuite/rust/compile/issue-1131.rs |  4 ++++
 2 files changed, 18 insertions(+)

diff --git a/gcc/rust/resolve/rust-ast-resolve-item.h b/gcc/rust/resolve/rust-ast-resolve-item.h
index 5d32c0022d0..f662d5df507 100644
--- a/gcc/rust/resolve/rust-ast-resolve-item.h
+++ b/gcc/rust/resolve/rust-ast-resolve-item.h
@@ -955,6 +955,15 @@ public:
 
   void visit (AST::ExternalFunctionItem &function) override
   {
+    NodeId scope_node_id = function.get_node_id ();
+    resolver->get_name_scope ().push (scope_node_id);
+    resolver->get_type_scope ().push (scope_node_id);
+    resolver->get_label_scope ().push (scope_node_id);
+    resolver->push_new_name_rib (resolver->get_name_scope ().peek ());
+    resolver->push_new_type_rib (resolver->get_type_scope ().peek ());
+    resolver->push_new_label_rib (resolver->get_type_scope ().peek ());
+
+    // resolve the generics
     if (function.has_generics ())
       {
 	for (auto &generic : function.get_generic_params ())
@@ -971,6 +980,11 @@ public:
       {
 	ResolveType::go (param.get_type ().get (), param.get_node_id ());
       }
+
+    // done
+    resolver->get_name_scope ().pop ();
+    resolver->get_type_scope ().pop ();
+    resolver->get_label_scope ().pop ();
   }
 
   void visit (AST::ExternalStaticItem &item) override
diff --git a/gcc/testsuite/rust/compile/issue-1131.rs b/gcc/testsuite/rust/compile/issue-1131.rs
new file mode 100644
index 00000000000..fd158abc700
--- /dev/null
+++ b/gcc/testsuite/rust/compile/issue-1131.rs
@@ -0,0 +1,4 @@
+extern "rust-intrinsic" {
+    fn size_of<T>() -> usize;
+    fn offset<T>(dst: *const T, offset: isize) -> *const T;
+}