[gcc r14-8571] gccrs: Emit an error on unsafe modules

[gcc r14-8571] gccrs: Emit an error on unsafe modules

[Arthur Cohen]

https://gcc.gnu.org/g:5959f32d28ff76b3e9c177914f034aae72c9a835

commit r14-8571-g5959f32d28ff76b3e9c177914f034aae72c9a835
Author: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>
Date:   Tue Nov 21 18:51:21 2023 +0100

    gccrs: Emit an error on unsafe modules
    
    An error should be emitted on unsafe modules during the AST validation
    pass as the syntax allows those even though they're not alowed later down
    the line.
    
    gcc/rust/ChangeLog:
    
            * ast/rust-item.h: Add safety getter to modules.
            * checks/errors/rust-ast-validation.cc (ASTValidation::visit): Check
            a module's safety and emit an error when meeting an unsafe module.
            * checks/errors/rust-ast-validation.h: Add function prototype.
            * parse/rust-parse-impl.h (Parser::parse_module): Move the module locus
            to the first token instead of the mod keyword.
    
    Signed-off-by: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>

Diff:
---
 gcc/rust/ast/rust-item.h                      |  2 ++
 gcc/rust/checks/errors/rust-ast-validation.cc | 10 ++++++++++
 gcc/rust/checks/errors/rust-ast-validation.h  |  1 +
 gcc/rust/parse/rust-parse-impl.h              |  3 ++-
 4 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/gcc/rust/ast/rust-item.h b/gcc/rust/ast/rust-item.h
index 6c3715e1eeb8..3bf023b3c5a7 100644
--- a/gcc/rust/ast/rust-item.h
+++ b/gcc/rust/ast/rust-item.h
@@ -840,6 +840,8 @@ public:
   // Returns the kind of the module
   enum ModuleKind get_kind () const { return kind; }
 
+  Unsafety get_unsafety () const { return safety; }
+
   // TODO: think of better way to do this - mutable getter seems dodgy
   const std::vector<Attribute> &get_inner_attrs () const { return inner_attrs; }
   std::vector<Attribute> &get_inner_attrs () { return inner_attrs; }
diff --git a/gcc/rust/checks/errors/rust-ast-validation.cc b/gcc/rust/checks/errors/rust-ast-validation.cc
index dad7f5edded6..4b209908f9e5 100644
--- a/gcc/rust/checks/errors/rust-ast-validation.cc
+++ b/gcc/rust/checks/errors/rust-ast-validation.cc
@@ -17,6 +17,7 @@
 // <http://www.gnu.org/licenses/>.
 
 #include "rust-ast-validation.h"
+#include "rust-common.h"
 #include "rust-diagnostics.h"
 #include "rust-item.h"
 #include "rust-keyword-values.h"
@@ -136,4 +137,13 @@ ASTValidation::visit (AST::Trait &trait)
   AST::ContextualASTVisitor::visit (trait);
 }
 
+void
+ASTValidation::visit (AST::Module &module)
+{
+  if (module.get_unsafety () == Unsafety::Unsafe)
+    rust_error_at (module.get_locus (), "module cannot be declared unsafe");
+
+  AST::ContextualASTVisitor::visit (module);
+}
+
 } // namespace Rust
diff --git a/gcc/rust/checks/errors/rust-ast-validation.h b/gcc/rust/checks/errors/rust-ast-validation.h
index 1052168ea728..01d923ceff33 100644
--- a/gcc/rust/checks/errors/rust-ast-validation.h
+++ b/gcc/rust/checks/errors/rust-ast-validation.h
@@ -34,6 +34,7 @@ public:
 
   void check (AST::Crate &crate) { AST::ContextualASTVisitor::visit (crate); }
 
+  virtual void visit (AST::Module &module);
   virtual void visit (AST::ConstantItem &const_item);
   virtual void visit (AST::Lifetime &lifetime);
   virtual void visit (AST::LoopLabel &label);
diff --git a/gcc/rust/parse/rust-parse-impl.h b/gcc/rust/parse/rust-parse-impl.h
index 8087e0c2b94b..f83cc122c893 100644
--- a/gcc/rust/parse/rust-parse-impl.h
+++ b/gcc/rust/parse/rust-parse-impl.h
@@ -2429,6 +2429,8 @@ std::unique_ptr<AST::Module>
 Parser<ManagedTokenSource>::parse_module (AST::Visibility vis,
 					  AST::AttrVec outer_attrs)
 {
+  location_t locus = lexer.peek_token ()->get_locus ();
+
   Unsafety safety = Unsafety::Normal;
   if (lexer.peek_token ()->get_id () == UNSAFE)
     {
@@ -2436,7 +2438,6 @@ Parser<ManagedTokenSource>::parse_module (AST::Visibility vis,
       skip_token (UNSAFE);
     }
 
-  location_t locus = lexer.peek_token ()->get_locus ();
   skip_token (MOD);
 
   const_TokenPtr module_name = expect_token (IDENTIFIER);