cite Herb Sutter quote re boundschecking if std::size is available + …

…hyloish arr.unsafe[idx] bypass syntax

include/boundscheck.cth

@@ -1,5 +1,15 @@
 include <iostream>
 
+cpp'
+#define CETO_UNSAFE_ARRAY_ACCESS(array, index) (array[index])
+'
+
+# Herb Sutter - ACCU 2024 - Keynote: Safety, Security, Safety and C / C++ - C++ Evolution
+# https://youtu.be/EB7yR-1317k?t=3373
+# "If you see an expression of the form a[b] and std::ssize is available,
+# including for C-arrays and vector and span and all those things,
+# just insert a 0 <= b < std::ssize(a) at the call site"
+
 defmacro (array[index], array, index:
     if (array.name() == "lambda":
         # not actually an array access (general syntax ftl)
@@ -8,8 +18,15 @@ defmacro (array[index], array, index:
     return quote(ceto.bounds_check(unquote(array), unquote(index)))
 )
 
+defmacro (array.unsafe[index], array, index:
+    return quote(CETO_UNSAFE_ARRAY_ACCESS(unquote(array), unquote(index)))
+)
+
 namespace (ceto)
 
+# Herb Sutter - ACCU Keynote
+# See slide at above URL:
+# "Inserting call-site bounds checks for a[b] if std::size(a) is available"
 if (defined(CETO_HAS_SOURCE_LOCATION):
     def (bounds_check, arr: mut:auto:ref:ref, index: size_t, loc: const:std.source_location:ref = std.source_location.current():
         if (index >= std.size(arr):
@@ -18,7 +35,7 @@ if (defined(CETO_HAS_SOURCE_LOCATION):
             std.terminate()
         )
 
-        return std.forward<decltype(arr)>(arr).unsafe_at(std.forward<decltype(index)>(index))
+        return std.forward<decltype(arr)>(arr).unsafe[std.forward<decltype(index)>(index)]
     ) : decltype(auto):requires:requires(std.size(arr))
 else:
     def (bounds_check, arr: mut:auto:ref:ref, index: size_t:
@@ -27,17 +44,17 @@ else:
             std.terminate()
         )
 
-        return std.forward<decltype(arr)>(arr).unsafe_at(std.forward<decltype(index)>(index))
+        return std.forward<decltype(arr)>(arr).unsafe[std.forward<decltype(index)>(index)]
     ) : decltype(auto):requires:requires(std.size(arr))
 ) : preprocessor
 
 def (bounds_check, non_array: mut:auto:ref:ref, obj: mut:auto:ref:ref:
-    return std.forward<decltype(non_array)>(non_array).unsafe_at(std.forward<decltype(obj)>(obj))
+    return std.forward<decltype(non_array)>(non_array).unsafe[std.forward<decltype(obj)>(obj)]
 ) : decltype(auto):requires:not std.is_integral_v<std.remove_cvref_t<decltype(obj)>>
 
 # from https://stackoverflow.com/questions/69785562/c-map-and-unordered-map-template-parameter-check-for-common-behavior-using-c/69869007#69869007
 is_map_type: template<class:T>:concept = std.same_as<typename:T.value_type, std.pair<const:typename:T.key_type, typename:T.mapped_type>>
 
 def (bounds_check, map_like: mut:auto:ref:ref, key: mut:auto:ref:ref:
-    return std.forward<decltype(map_like)>(map_like).unsafe_at(std.forward<decltype(key)>(key))
+    return std.forward<decltype(map_like)>(map_like).unsafe[std.forward<decltype(key)>(key)]
 ) : decltype(auto):requires:std.is_integral_v<std.remove_cvref_t<decltype(key)>> and is_map_type<std.remove_cvref_t<decltype(map_like)>>