Improve macro repetition handling

gcc/rust/ChangeLog:

	* expand/rust-macro-expand.cc
	(MacroExpander::match_matcher): Remove append_fragment inside repetitions.
	(MacroExpander::match_n_matches): Use sub_stack push/pop to handle repetitions.
	(MatchedFragmentContainer::add_fragment): Add MatchedFragmentContainer accepting version.
	* expand/rust-macro-expand.h
	(MatchedFragmentContainer::add_fragment): Likewise.
	(MatchedFragmentContainerRepetition::add_fragment): Likewise.
	(SubstititionScope::append_fragment): Likewise.

gcc/testsuite/ChangeLog:

	* rust/compile/macro56.rs: New test.

Signed-off-by: Owen Avery <powerboat9.gamer@gmail.com>

3 files changed, 63 insertions, 16 deletions

diff --git a/gcc/rust/expand/rust-macro-expand.cc b/gcc/rust/expand/rust-macro-expand.cc
index 7cacb39..e313e1a 100644
--- a/gcc/rust/expand/rust-macro-expand.cc
+++ b/gcc/rust/expand/rust-macro-expand.cc
@@ -501,14 +501,9 @@ MacroExpander::match_matcher (Parser<MacroInvocLexer> &parser,
 
 	    // matched fragment get the offset in the token stream
 	    size_t offs_end = source.get_offs ();
-	    if (in_repetition)
-	      sub_stack.append_fragment (
-		MatchedFragment (fragment->get_ident ().as_string (),
-				 offs_begin, offs_end));
-	    else
-	      sub_stack.insert_metavar (
-		MatchedFragment (fragment->get_ident ().as_string (),
-				 offs_begin, offs_end));
+	    sub_stack.insert_metavar (
+	      MatchedFragment (fragment->get_ident ().as_string (), offs_begin,
+			       offs_end));
 	  }
 	  break;
 
@@ -598,6 +593,7 @@ MacroExpander::match_n_matches (Parser<MacroInvocLexer> &parser,
 	if (!match_token (parser, *rep.get_sep ()))
 	  break;
 
+      sub_stack.push ();
       bool valid_current_match = false;
       for (auto &match : matches)
 	{
@@ -612,13 +608,7 @@ MacroExpander::match_n_matches (Parser<MacroInvocLexer> &parser,
 		// matched fragment get the offset in the token stream
 		size_t offs_end = source.get_offs ();
 
-		// The main difference with match_matcher happens here: Instead
-		// of inserting a new fragment, we append to one. If that
-		// fragment does not exist, then the operation is similar to
-		// `insert_fragment` with the difference that we are not
-		// creating a metavariable, but a repetition of one, which is
-		// really different.
-		sub_stack.append_fragment (
+		sub_stack.insert_metavar (
 		  MatchedFragment (fragment->get_ident ().as_string (),
 				   offs_begin, offs_end));
 	      }
@@ -645,6 +635,12 @@ MacroExpander::match_n_matches (Parser<MacroInvocLexer> &parser,
 	      break;
 	    }
 	}
+      auto old_stack = sub_stack.pop ();
+
+      // nest metavars into repetitions
+      for (auto &ent : old_stack)
+	sub_stack.append_fragment (ent.first, std::move (ent.second));
+
       // If we've encountered an error once, stop trying to match more
       // repetitions
       if (!valid_current_match)
@@ -1201,6 +1197,16 @@ MatchedFragmentContainer::add_fragment (MatchedFragment fragment)
     .add_fragment (fragment);
 }
 
+void
+MatchedFragmentContainer::add_fragment (
+  std::unique_ptr<MatchedFragmentContainer> fragment)
+{
+  rust_assert (!is_single_fragment ());
+
+  return static_cast<MatchedFragmentContainerRepetition &> (*this)
+    .add_fragment (std::move (fragment));
+}
+
 std::unique_ptr<MatchedFragmentContainer>
 MatchedFragmentContainer::zero ()
 {
diff --git a/gcc/rust/expand/rust-macro-expand.h b/gcc/rust/expand/rust-macro-expand.h
index 19e71f7..e566d5d 100644
--- a/gcc/rust/expand/rust-macro-expand.h
+++ b/gcc/rust/expand/rust-macro-expand.h
@@ -111,6 +111,11 @@ public:
    */
   void add_fragment (MatchedFragment fragment);
 
+  /**
+   * Add a matched fragment to the container
+   */
+  void add_fragment (std::unique_ptr<MatchedFragmentContainer> fragment);
+
   // const std::string &get_fragment_name () const { return fragment_name; }
 
   bool is_single_fragment () const { return get_kind () == Kind::MetaVar; }
@@ -155,7 +160,15 @@ public:
    */
   void add_fragment (MatchedFragment fragment)
   {
-    fragments.emplace_back (metavar (fragment));
+    add_fragment (metavar (fragment));
+  }
+
+  /**
+   * Add a matched fragment to the container
+   */
+  void add_fragment (std::unique_ptr<MatchedFragmentContainer> fragment)
+  {
+    fragments.emplace_back (std::move (fragment));
   }
 
   virtual Kind get_kind () const { return Kind::Repetition; }
@@ -227,6 +240,25 @@ public:
     it->second->add_fragment (fragment);
   }
 
+  /**
+   * Append a new matched fragment to a repetition into the current substitution
+   * map
+   */
+  void append_fragment (std::string ident,
+			std::unique_ptr<MatchedFragmentContainer> fragment)
+  {
+    auto &current_map = stack.back ();
+    auto it = current_map.find (ident);
+
+    if (it == current_map.end ())
+      it = current_map
+	     .emplace (ident, std::unique_ptr<MatchedFragmentContainer> (
+				new MatchedFragmentContainerRepetition ()))
+	     .first;
+
+    it->second->add_fragment (std::move (fragment));
+  }
+
   void insert_matches (std::string key,
 		       std::unique_ptr<MatchedFragmentContainer> matches)
   {
diff --git a/gcc/testsuite/rust/compile/macro56.rs b/gcc/testsuite/rust/compile/macro56.rs
new file mode 100644
index 0000000..bf42a64
--- /dev/null
+++ b/gcc/testsuite/rust/compile/macro56.rs
@@ -0,0 +1,9 @@
+macro_rules! check {
+    (a, b, c ; x, y, z; e, r; a) => {}
+}
+
+macro_rules! foo {
+    ($($($i:ident),*);*) => {check!($($($i),*);*);}
+}
+
+foo!(a, b, c ; x, y, z; e, r; a);