Only use std::as_const to capture by const ref in the immediately inv…

…oked (TODO nonescaping) case. Make return value of ceto::default_capture const for the other cases.

ceto/codegen.py

@@ -562,7 +562,7 @@ def is_capture(n):
             capture_list = ["&" + i + " = " + "std::as_const(" + i + ")" for i in possible_captures]
         else:
             # capture only a few things by const value (shared/weak instances, arithithmetic_v, enums):
-            capture_list = [i + " = " + "std::as_const(ceto::default_capture(" + i + "))" for i in possible_captures]
+            capture_list = [i + " = " + "ceto::default_capture(" + i + ")" for i in possible_captures]
     else:
         capture_list = ""
 

include/ceto.h

@@ -290,19 +290,19 @@ call_or_construct(TArgs&&... args) {
 
 // this one may be controversial (strong capture of shared object references by default - use 'weak' to break cycle)
 template <class T>
-std::enable_if_t<std::is_base_of_v<object, T>, std::shared_ptr<T>>  // We now autoderef all shared/unique_ptrs not just to ceto class instances. doing the same for lambda capture might go a bit too far - don't want to encourange writing shared_ptr<vector<int>> instead of creating a wrapper class instance that's automatically placed in the capture list
+std::enable_if_t<std::is_base_of_v<object, T>, const std::shared_ptr<T>>  // We now autoderef all shared/unique_ptrs not just to ceto class instances. doing the same for lambda capture might go a bit too far - don't want to encourange writing shared_ptr<vector<int>> instead of creating a wrapper class instance that's automatically placed in the capture list
 constexpr default_capture(std::shared_ptr<T> t) {
     return t;
 }
 
 template <class T>
-std::enable_if_t<std::is_base_of_v<object, T>, std::weak_ptr<T>>
+std::enable_if_t<std::is_base_of_v<object, T>, const std::weak_ptr<T>>
 constexpr default_capture(std::weak_ptr<T> t) {
     return t;
 }
 
 template <class T>
-std::enable_if_t<std::is_arithmetic_v<T> || std::is_enum_v<T>, T>
+std::enable_if_t<std::is_arithmetic_v<T> || std::is_enum_v<T>, const T>
 constexpr default_capture(T t) {
     return t;
 }

tests/regression/capture.donotedit.autogenerated.cpp

@@ -56,7 +56,7 @@ auto foo(const T1& x) const -> void {
                 };
         l();
         const auto i = std::make_shared<const decltype(Inner{f})>(f);
-        [&]() {
+        [&x = std::as_const(x), &i = std::as_const(i)]() {
                 if constexpr (!std::is_void_v<decltype((*ceto::mad(i)).foo(x))>) { return (*ceto::mad(i)).foo(x); } else { static_cast<void>((*ceto::mad(i)).foo(x)); };
                 }();
     }