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

---
 include/elna/boot/result.h     | 28 +++++++++++++++++-----------
 include/elna/boot/type_check.h | 15 ++++++++++++++-
 2 files changed, 31 insertions(+), 12 deletions(-)

(limited to 'include')

diff --git a/include/elna/boot/result.h b/include/elna/boot/result.h
index 4c6046d..56884ff 100644
--- a/include/elna/boot/result.h
+++ b/include/elna/boot/result.h
@@ -268,17 +268,7 @@ namespace elna::boot
 
         bool is_signed() const;
         std::size_t size() const;
-
-        template<typename T>
-        T to() const
-            requires is_integral<T>
-        {
-            T result{};
-
-            mpz_export(&result, nullptr, 1, sizeof(T), 0, 0, this->raw);
-
-            return result;
-        }
+        std::string to_string(const std::uint8_t base = 10U) const;
 
         /**
          * Exports the stored value as a host \c std::ptrdiff_t.
@@ -294,6 +284,21 @@ namespace elna::boot
          */
         std::optional<std::size_t> to_unsigned() const;
 
+        /**
+         * Attempts to narrow this literal's internally stored size to
+         * \p target_size bytes, in place.
+         *
+         * If the current value can be represented within \p target_size bytes
+         * (given the literal's existing signedness), the internal storage size
+         * is updated to \p target_size and the function returns \c true. If the
+         * value would not fit, the literal is left unmodified and \c false is
+         * returned.
+         *
+         * \param target_size Size of the target type in bytes.
+         * \return Whether the value fits and has been changed.
+         */
+        bool fit_into(const std::size_t target_size);
+
         template<typename T>
         static integer_literal from(T initial)
             requires is_integral<T>
@@ -313,6 +318,7 @@ namespace elna::boot
         mpz_t raw;
 
         integer_literal(bool is_signed, std::size_t size);
+        bool fits_in(const std::size_t bits) const;
         std::optional<integer_literal> check() &&;
         bool is_negative_minimum(const std::size_t bits) const;
         bool is_negative_minimum() const;
diff --git a/include/elna/boot/type_check.h b/include/elna/boot/type_check.h
index 628af06..82f0092 100644
--- a/include/elna/boot/type_check.h
+++ b/include/elna/boot/type_check.h
@@ -54,6 +54,10 @@ namespace elna::boot
         {
             type target;
         };
+        struct integer_literal_overflow
+        {
+            integer_literal overflow;
+        };
         enum class kind {
             record_base,
             for_range,
@@ -63,7 +67,15 @@ namespace elna::boot
             non_indexable,
             dereference_of_non_pointer
         };
-        using payload_type = std::variant<expected_type, return_type, unary, binary, invalid_cast, kind>;
+        using payload_type = std::variant<
+            expected_type,
+            return_type,
+            unary,
+            binary,
+            invalid_cast,
+            integer_literal_overflow,
+            kind
+        >;
 
         type_mismatch_error(const source_position position,
                 type actual, payload_type payload);
@@ -213,5 +225,6 @@ namespace elna::boot
         void visit(cast_expression *expression) override;
         void visit(unary_expression *expression) override;
         void visit(binary_expression *expression) override;
+        void visit(literal<integer_literal> *expression) override;
     };
 }
-- 
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