Disallow "[n] const T"

3 files changed, 39 insertions, 10 deletions

diff --git a/boot/name_analysis.cc b/boot/name_analysis.cc
index cfc4e35..48251cd 100644
--- a/boot/name_analysis.cc
+++ b/boot/name_analysis.cc
@@ -51,8 +51,7 @@ namespace elna::boot
         return "Symbol '" + identifier + "' has been already defined";
     }
 
-    std::optional<std::pair<std::string, source_position>>
-        redefinition_error::note() const
+    std::optional<std::pair<std::string, source_position>> redefinition_error::note() const
     {
         if (original.has_value() && original->start().available())
         {
@@ -61,6 +60,16 @@ namespace elna::boot
         return std::nullopt;
     }
 
+    const_array_error::const_array_error(const source_position position)
+        : error(position)
+    {
+    }
+
+    std::string const_array_error::what() const
+    {
+        return "const must be written before the array size, not after";
+    }
+
     // Members of a constant aggregate are constant themselves.
     static type qualify_member_type(const type& element, const type& aggregate)
     {
@@ -176,9 +185,12 @@ namespace elna::boot
     void name_analysis_visitor::visit(array_type_expression *expression)
     {
         walking_visitor::visit(expression);
-        auto result_type = std::make_shared<array_type>(this->current_type, expression->size);
 
-        this->current_type = type(result_type);
+        if (this->current_type.get<constant_type>() != nullptr)
+        {
+            add_error<const_array_error>(expression->position());
+        }
+        this->current_type = type(std::make_shared<array_type>(this->current_type, expression->size));
     }
 
     /**
diff --git a/include/elna/boot/name_analysis.h b/include/elna/boot/name_analysis.h
index 4498d0c..feef3bf 100644
--- a/include/elna/boot/name_analysis.h
+++ b/include/elna/boot/name_analysis.h
@@ -40,16 +40,14 @@ namespace elna::boot
             local_export
         };
 
-    private:
-        std::string identifier;
-        kind error_kind;
-
-    public:
-
         declaration_error(const kind error_kind,
                 const boot::identifier& identifier);
 
         std::string what() const override;
+
+    private:
+        std::string identifier;
+        kind error_kind;
     };
 
     /**
@@ -71,6 +69,18 @@ namespace elna::boot
     };
 
     /**
+     * Array size before \c const is not valid — only \c const [n]T is
+     * accepted, not \c [n]const T.
+     */
+    class const_array_error : public error
+    {
+    public:
+        explicit const_array_error(const source_position position);
+
+        std::string what() const override;
+    };
+
+    /**
      * Origin of a field in a composite type.
      */
     struct field_origin
diff --git a/testsuite/fail_compilation/const_array.elna b/testsuite/fail_compilation/const_array.elna
new file mode 100644
index 0000000..7a1a6f5
--- /dev/null
+++ b/testsuite/fail_compilation/const_array.elna
@@ -0,0 +1,7 @@
+proc f()
+var
+  a: [10]const Int (* @Error const must be written before the array size, not after *)
+begin
+return
+
+end.