From: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>
Date: Mon, 5 Jun 2023 11:17:22 +0000 (+0200)
Subject: gccrs: expand: Allow empty derive attribute
X-Git-Tag: basepoints/gcc-15~2475
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=da450d345c948d9be1fca29d01fa1153c2ddf3bd;p=thirdparty%2Fgcc.git

gccrs: expand: Allow empty derive attribute

Changes derive macro expansion to accept empty derive attributes. This
commit also add a test to prevent future regressions.

gcc/rust/ChangeLog:

	* expand/rust-expand-visitor.cc (get_traits_to_derive): Change
	assertion to allow empty derive directives.

gcc/testsuite/ChangeLog:

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

Signed-off-by: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>
---

diff --git a/gcc/rust/expand/rust-expand-visitor.cc b/gcc/rust/expand/rust-expand-visitor.cc
index 927d9225049e..c7a5f573d7ed 100644
--- a/gcc/rust/expand/rust-expand-visitor.cc
+++ b/gcc/rust/expand/rust-expand-visitor.cc
@@ -72,7 +72,7 @@ get_traits_to_derive (AST::Attribute &attr)
 	  = static_cast<AST::DelimTokenTree &> (input).get_token_trees ();
 
 	// erase the delimiters
-	rust_assert (tokens.size () >= 3);
+	rust_assert (tokens.size () >= 2);
 	tokens.erase (tokens.begin ());
 	tokens.pop_back ();
 
diff --git a/gcc/testsuite/rust/compile/derive_empty.rs b/gcc/testsuite/rust/compile/derive_empty.rs
new file mode 100644
index 000000000000..21c67f01d6cd
--- /dev/null
+++ b/gcc/testsuite/rust/compile/derive_empty.rs
@@ -0,0 +1,6 @@
+#[derive()]
+struct UnderivedStruct;
+
+fn main() {
+    let _ = UnderivedStruct;
+}