From 71b3bbb7698b13b42c99a4ca66c27db4a6189ff8 Mon Sep 17 00:00:00 2001
From: Eugen Wissner <belka@caraus.de>
Date: Sat, 1 Aug 2026 16:05:51 +0200
Subject: Enforce integral values in slice ranges

---
 boot/type_check.cc | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

(limited to 'boot/type_check.cc')

diff --git a/boot/type_check.cc b/boot/type_check.cc
index 07deb2d..529f66a 100644
--- a/boot/type_check.cc
+++ b/boot/type_check.cc
@@ -165,6 +165,11 @@ namespace elna::boot
                 return "Type '" + this->actual.to_string()
                     + "' cannot be converted to '" + payload.target.to_string() + "'";
             }
+            else if constexpr (std::is_same_v<T, integer_literal_overflow>)
+            {
+                return "The number " + payload.overflow.to_string()
+                    + " does not fit into the type '" + actual.to_string() + "'";
+            }
             else if constexpr (std::is_same_v<T, kind>)
             {
                 switch (payload)
@@ -762,6 +767,17 @@ namespace elna::boot
     void type_analysis_visitor::visit(slicing_expression *expression)
     {
         walking_visitor::visit(expression);
+
+        if (!is_integral_type(resolve_underlying_type(expression->start().type_decoration)))
+        {
+            add_error<type_mismatch_error>(expression->start().position(),
+                    expression->start().type_decoration, type_mismatch_error::kind::array_index);
+        }
+        if (!is_integral_type(resolve_underlying_type(expression->end().type_decoration)))
+        {
+            add_error<type_mismatch_error>(expression->end().position(),
+                    expression->end().type_decoration, type_mismatch_error::kind::array_index);
+        }
     }
 
     void type_analysis_visitor::visit(array_access_expression *expression)
@@ -1008,4 +1024,22 @@ namespace elna::boot
             }
         }
     }
+
+    void type_analysis_visitor::visit(literal<integer_literal> *expression)
+    {
+        bool narrowed{ false };
+        if (expression->value.is_signed())
+        {
+            narrowed = expression->value.fit_into(target.int_properties.size);
+        }
+        else
+        {
+            narrowed = expression->value.fit_into(target.word_properties.size);
+        }
+        if (!narrowed)
+        {
+            add_error<type_mismatch_error>(expression->position(), expression->type_decoration,
+                    type_mismatch_error::integer_literal_overflow{ expression->value });
+        }
+    }
 }
-- 
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