gccrs: add non camel case types lint

gcc/rust/ChangeLog:

	* checks/lints/unused/rust-unused-checker.cc (is_camel_case):
	Add warning for struct, enum, and trait.
	(UnusedChecker::visit):
	New.
	* checks/lints/unused/rust-unused-checker.h:
	New.

gcc/testsuite/ChangeLog:

	* rust/compile/non-camel-case-types_0.rs: New test.

Signed-off-by: Lucas Ly Ba <lucas.ly-ba@outlook.com>

Author: lucasly-ba

gcc/rust/checks/lints/unused/rust-unused-checker.cc

@@ -19,9 +19,9 @@
 #include "rust-unused-checker.h"
 #include "rust-hir-expr.h"
 #include "rust-hir-item.h"
-
 #include "options.h"
 #include "rust-keyword-values.h"
+#include <cctype>
 
 namespace Rust {
 namespace Analysis {
@@ -124,6 +124,51 @@ UnusedChecker::visit (HIR::EmptyStmt &stmt)
 		   "unnecessary trailing semicolons");
 }
 
+bool
+is_camel_case (Identifier identifier)
+{
+  auto s = identifier.as_string ();
+  return ISUPPER (s.front ())
+	 && std::all_of (s.begin (), s.end (),
+			 [] (unsigned char c) { return ISALNUM (c); });
+}
+
+void
+UnusedChecker::visit (HIR::Trait &trait)
+{
+  if (!is_camel_case (trait.get_name ()))
+    rust_warning_at (trait.get_locus (), OPT_Wunused_variable,
+		     "trait %qs should have an upper camel case name",
+		     trait.get_name ().as_string ().c_str ());
+}
+
+void
+UnusedChecker::visit (HIR::StructStruct &strct)
+{
+  if (!is_camel_case (strct.get_identifier ()))
+    rust_warning_at (strct.get_locus (), OPT_Wunused_variable,
+		     "struct %qs should have an upper camel case name",
+		     strct.get_identifier ().as_string ().c_str ());
+}
+
+void
+UnusedChecker::visit (HIR::TupleStruct &strct)
+{
+  if (!is_camel_case (strct.get_identifier ()))
+    rust_warning_at (strct.get_locus (), OPT_Wunused_variable,
+		     "struct %qs should have an upper camel case name",
+		     strct.get_identifier ().as_string ().c_str ());
+}
+
+void
+UnusedChecker::visit (HIR::Enum &enm)
+{
+  if (!is_camel_case (enm.get_identifier ()))
+    rust_warning_at (enm.get_locus (), OPT_Wunused_variable,
+		     "enum %qs should have an upper camel case name",
+		     enm.get_identifier ().as_string ().c_str ());
+}
+
 void
 UnusedChecker::visit_loop_label (HIR::LoopLabel &label)
 {

gcc/rust/checks/lints/unused/rust-unused-checker.h

@@ -44,6 +44,10 @@ class UnusedChecker : public HIR::DefaultHIRVisitor
   virtual void visit (HIR::AssignmentExpr &identifier) override;
   virtual void visit (HIR::StructPatternFieldIdent &identifier) override;
   virtual void visit (HIR::EmptyStmt &stmt) override;
+  virtual void visit (HIR::Trait &item) override;
+  virtual void visit (HIR::StructStruct &strct) override;
+  virtual void visit (HIR::TupleStruct &strct) override;
+  virtual void visit (HIR::Enum &enm) override;
   virtual void visit_loop_label (HIR::LoopLabel &label) override;
 };
 } // namespace Analysis

gcc/testsuite/rust/compile/non-camel-case-types_0.rs

@@ -0,0 +1,11 @@
+// { dg-additional-options "-frust-unused-check-2.0" }
+
+struct my_struct; // { dg-warning "struct is never constructed: .my.struct." }
+// { dg-warning "struct .my.struct. should have an upper camel case name" "" { target *-*-* } .-1 }
+
+enum my_enum {}
+// { dg-warning "enum .my.enum. should have an upper camel case name" "" { target *-*-* } .-1 }
+
+trait my_trait {}
+// { dg-warning "trait .my.trait. should have an upper camel case name" "" { target *-*-* } .-1 }
+