Merge #969

969: Add builtin macros framework r=CohenArthur a=CohenArthur

This PR adds bases to define new builtin macro functions.

Since we operate at the `insert_macro_def` level, this requires builtin macros to be defined, as is the case in the rust standard library:

```rust
    macro_rules! assert {
        ($cond:expr $(,)?) => {{ /* compiler built-in */ }};
        ($cond:expr, $($arg:tt)+) => {{ /* compiler built-in */ }};
    }
```

Co-authored-by: Arthur Cohen <arthur.cohen@embecosm.com>

1 files changed, 16 insertions, 4 deletions

diff --git a/gcc/rust/expand/rust-macro-expand.cc b/gcc/rust/expand/rust-macro-expand.cc
index b54aa01..7552e82 100644
--- a/gcc/rust/expand/rust-macro-expand.cc
+++ b/gcc/rust/expand/rust-macro-expand.cc
@@ -3194,8 +3194,14 @@ MacroExpander::expand_invoc (AST::MacroInvocation &invoc)
   bool ok = mappings->lookup_macro_def (resolved_node, &rules_def);
   rust_assert (ok);
 
-  auto fragment
-    = expand_decl_macro (invoc.get_locus (), invoc_data, *rules_def, false);
+  auto fragment = AST::ASTFragment::create_empty ();
+
+  if (rules_def->is_builtin ())
+    fragment
+      = rules_def->get_builtin_transcriber () (invoc.get_locus (), invoc_data);
+  else
+    fragment
+      = expand_decl_macro (invoc.get_locus (), invoc_data, *rules_def, false);
 
   // lets attach this fragment to the invocation
   invoc.set_fragment (std::move (fragment));
@@ -3229,8 +3235,14 @@ MacroExpander::expand_invoc_semi (AST::MacroInvocationSemi &invoc)
   bool ok = mappings->lookup_macro_def (resolved_node, &rules_def);
   rust_assert (ok);
 
-  auto fragment
-    = expand_decl_macro (invoc.get_locus (), invoc_data, *rules_def, true);
+  auto fragment = AST::ASTFragment::create_empty ();
+
+  if (rules_def->is_builtin ())
+    fragment
+      = rules_def->get_builtin_transcriber () (invoc.get_locus (), invoc_data);
+  else
+    fragment
+      = expand_decl_macro (invoc.get_locus (), invoc_data, *rules_def, true);
 
   // lets attach this fragment to the invocation
   invoc.set_fragment (std::move (fragment));