[committed 03/88] gccrs: Check for mutable references in const functions

[arthur.cohen@embecosm.com]

From: Dave <dme2223@gmail.com>

Use StackedContext instead. Fix error string

Signed-off-by: Dave Evans <dave@dmetwo.org>

(Squashed commits) Check for mutable references in const functions using StackedContext

gcc/rust/ChangeLog:

	* checks/errors/rust-const-checker.cc (ConstChecker::visit): Use StackedContext
	class.

gcc/testsuite/ChangeLog:

	* rust/compile/const10.rs: New test.

Signed-off-by: Dave Evans <dave@dmetwo.org>
---
 gcc/rust/checks/errors/rust-const-checker.cc | 8 ++++++--
 gcc/testsuite/rust/compile/const10.rs        | 3 +++
 2 files changed, 9 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/rust/compile/const10.rs

diff --git a/gcc/rust/checks/errors/rust-const-checker.cc b/gcc/rust/checks/errors/rust-const-checker.cc
index 576c1b170d6..7e31c9f9c28 100644
--- a/gcc/rust/checks/errors/rust-const-checker.cc
+++ b/gcc/rust/checks/errors/rust-const-checker.cc
@@ -898,8 +898,12 @@ ConstChecker::visit (RawPointerType &)
 {}
 
 void
-ConstChecker::visit (ReferenceType &)
-{}
+ConstChecker::visit (ReferenceType &type)
+{
+  if (const_context.is_in_context () && type.is_mut ())
+    rust_error_at (type.get_locus (),
+		   "mutable references are not allowed in constant functions");
+}
 
 void
 ConstChecker::visit (ArrayType &type)
diff --git a/gcc/testsuite/rust/compile/const10.rs b/gcc/testsuite/rust/compile/const10.rs
new file mode 100644
index 00000000000..9ab82744fbd
--- /dev/null
+++ b/gcc/testsuite/rust/compile/const10.rs
@@ -0,0 +1,3 @@
+const fn foo (a: &mut i32) { // { dg-error "mutable references are not allowed in constant functions" }
+	*a = 1;
+}
-- 
2.40.0