Support arbitrary unsigned integer attributes (#3591)

Fixes #3586. On macOS, `size_t` resolves to `unsigned long` whereas `uint64_t`
resolves to `unsigned long long`. Even though the types have the same bit-width
and signedness, they are not considered the same type. This caused issues with
`Attribute`s that store `size_t` values because we only specialized the
`getTable()` struct for `uint64_t`. This commit changes the specialization to
work for arbitrary unsigned integer types of at most 64-bit. It does that by
generalizing the specialization of `getTable()` and by implementing a
`KindValueToTableValueMapping` for unsigned integer attributes of up to 64-bit
that casts integers between the attributes bit-width and `uint64_t`.

1 files changed, 13 insertions, 4 deletions

diff --git a/src/expr/attribute.h b/src/expr/attribute.h
index 46302fc9f..44bf7aae5 100644
--- a/src/expr/attribute.h
+++ b/src/expr/attribute.h
@@ -61,7 +61,7 @@ class AttributeManager {
    * getTable<> is a helper template that gets the right table from an
    * AttributeManager given its type.
    */
-  template <class T, bool context_dep>
+  template <class T, bool context_dep, class Enable>
   friend struct getTable;
 
   bool d_inGarbageCollection;
@@ -190,8 +190,13 @@ namespace attr {
 /**
  * The getTable<> template provides (static) access to the
  * AttributeManager field holding the table.
+ *
+ * The `Enable` template parameter is used to instantiate the template
+ * conditionally: If the template substitution of Enable fails (e.g. when using
+ * `std::enable_if` in the template parameter and the condition is false), the
+ * instantiation is ignored due to the SFINAE rule.
  */
-template <class T, bool context_dep>
+template <class T, bool context_dep, class Enable = void>
 struct getTable;
 
 /** Access the "d_bools" member of AttributeManager. */
@@ -208,8 +213,12 @@ struct getTable<bool, false> {
 };
 
 /** Access the "d_ints" member of AttributeManager. */
-template <>
-struct getTable<uint64_t, false> {
+template <class T>
+struct getTable<T,
+                false,
+                // Use this specialization only for unsigned integers
+                typename std::enable_if<std::is_unsigned<T>::value>::type>
+{
   static const AttrTableId id = AttrTableUInt64;
   typedef AttrHash<uint64_t> table_type;
   static inline table_type& get(AttributeManager& am) {