[gccrs COMMIT 1/2] gccrs: respect cfg_attr expansion

[gerris.rs@gmail.com]

From: "lenny.chiadmi-delage" <lenny.chiadmi-delage@epita.fr>

Fix cfg_attr expansion and feature gate attribute handling

Fixes Rust-GCC#4245

gcc/rust/ChangeLog:

	* checks/errors/feature/rust-feature-gate.cc (FeatureGate::visit): Added
	handling for META_ITEM type attributes to properly process feature gates.
	* expand/rust-cfg-strip.cc (expand_cfg_attrs): Fixed a bug where
	newly inserted cfg_attr attributes wheren't being reprocessed,
	and cleaned up the loop increment logic.

Signed-off-by: lenny.chiadmi-delage <lenny.chiadmi-delage@epita.fr>
---
This change was merged into the gccrs repository and is posted here for
upstream visibility and potential drive-by review, as requested by GCC
release managers.
Each commit email contains a link to its details on github from where you can
find the Pull-Request and associated discussions.


Commit on github: https://github.com/Rust-GCC/gccrs/commit/5712c79af097da357057d57b6de0f6697b8fa1f1
The commit is not linked to any pull-request

 .../checks/errors/feature/rust-feature-gate.cc   | 16 ++++++++++++++++
 gcc/rust/expand/rust-cfg-strip.cc                | 10 ++++++----
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/gcc/rust/checks/errors/feature/rust-feature-gate.cc b/gcc/rust/checks/errors/feature/rust-feature-gate.cc
index 9df822b7e..e5170b778 100644
--- a/gcc/rust/checks/errors/feature/rust-feature-gate.cc
+++ b/gcc/rust/checks/errors/feature/rust-feature-gate.cc
@@ -69,6 +69,22 @@ FeatureGate::visit (AST::Crate &crate)
 		    valid_lib_features.emplace (name_str, item->get_locus ());
 		}
 	    }
+	  else if (type == AST::AttrInput::AttrInputType::META_ITEM)
+	    {
+	      const auto &meta_item
+		= static_cast<const AST::AttrInputMetaItemContainer &> (
+		  attr_input);
+	      for (const auto &item : meta_item.get_items ())
+		{
+		  const auto &name_str = item->as_string ();
+
+		  // TODO: detect duplicates
+		  if (auto tname = Feature::as_name (name_str))
+		    valid_lang_features.insert (tname.value ());
+		  else
+		    valid_lib_features.emplace (name_str, item->get_locus ());
+		}
+	    }
 	}
     }
 
diff --git a/gcc/rust/expand/rust-cfg-strip.cc b/gcc/rust/expand/rust-cfg-strip.cc
index 3c5e74e7a..e8c6c3789 100644
--- a/gcc/rust/expand/rust-cfg-strip.cc
+++ b/gcc/rust/expand/rust-cfg-strip.cc
@@ -124,6 +124,12 @@ expand_cfg_attrs (AST::AttrVec &attrs)
 	      attrs.insert (attrs.begin () + i,
 			    std::make_move_iterator (new_attrs.begin ()),
 			    std::make_move_iterator (new_attrs.end ()));
+
+	      /* Decrement i so that the for loop's i++ will bring us back to
+	       * position i, allowing us to reprocess the newly inserted
+	       * attribute (in case it's also a cfg_attr that needs expansion)
+	       */
+	      i--;
 	    }
 
 	  /* do something - if feature (first token in tree) is in fact enabled,
@@ -133,10 +139,6 @@ expand_cfg_attrs (AST::AttrVec &attrs)
 	   * recursive, so check for expanded attributes being recursive and
 	   * possibly recursively call the expand_attrs? */
 	}
-      else
-	{
-	  i++;
-	}
     }
   attrs.shrink_to_fit ();
 }

base-commit: 49002a872e07a14ad4e17a0dcdca60096c1ee62b
-- 
2.52.0