Add support for concatenating string literals with/without interpolat…

…ions And test by applying throughout `reflect.h2` => we don't need a separate regression test case for the feature, `reflect.h2` exercises it well
hsutter · Jul 10, 2024 · 2803292 · 2803292
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diff --git a/regression-tests/test-results/mixed-as-for-variant-20-types.cpp b/regression-tests/test-results/mixed-as-for-variant-20-types.cpp
diff --git a/regression-tests/test-results/mixed-default-arguments.cpp b/regression-tests/test-results/mixed-default-arguments.cpp
@@ -27,7 +27,7 @@ auto main() -> int;
 
 #line 5 "mixed-default-arguments.cpp2"
 auto cxx2(cpp2::impl::in<int> x, cpp2::impl::in<std::string> y) -> void{
-    std::cout << (cpp2::to_string(x) + " \"" + cpp2::to_string(y) + "\"\n");
+    std::cout << "" + (cpp2::to_string(x) + " \"" + cpp2::to_string(y) + "\"\n") + "";
 }
 
 #line 9 "mixed-default-arguments.cpp2"

diff --git a/regression-tests/test-results/mixed-fixed-type-aliases.cpp b/regression-tests/test-results/mixed-fixed-type-aliases.cpp
@@ -59,6 +59,6 @@ auto test(auto const& x) -> void{
     for ( auto const& arg : args ) 
         std::cout << CPP2_UFCS(filename)(std::filesystem::path(arg)) << "\n";
 
-    std::cout << (cpp2::to_string(mytype<int>::myvalue<int>) + "\n");
+    std::cout << "" + (cpp2::to_string(mytype<int>::myvalue<int>) + "\n") + "";
 }
 
diff --git a/regression-tests/test-results/mixed-inspect-templates.cpp b/regression-tests/test-results/mixed-inspect-templates.cpp
@@ -58,14 +58,14 @@ struct my_type {};
     std::variant<int,double,std::string> var {"C++ rulez"}; 
     my_type<int,double> myt {}; 
 
-    std::cout << ("inspected vec : " + cpp2::to_string(fun(vec))) << std::endl;
-    std::cout << ("inspected arr : " + cpp2::to_string(fun(arr))) << std::endl;
-    std::cout << ("inspected var : " + cpp2::to_string(fun(var))) << std::endl;
-    std::cout << ("inspected myt : " + cpp2::to_string(fun(myt))) << std::endl;
-
-    std::cout << ("inspected vec : " + cpp2::to_string(fun2(cpp2::move(vec)))) << std::endl;
-    std::cout << ("inspected arr : " + cpp2::to_string(fun2(cpp2::move(arr)))) << std::endl;
-    std::cout << ("inspected var : " + cpp2::to_string(fun2(cpp2::move(var)))) << std::endl;
-    std::cout << ("inspected myt : " + cpp2::to_string(fun2(cpp2::move(myt)))) << std::endl;
+    std::cout << "" + ("inspected vec : " + cpp2::to_string(fun(vec))) + "" << std::endl;
+    std::cout << "" + ("inspected arr : " + cpp2::to_string(fun(arr))) + "" << std::endl;
+    std::cout << "" + ("inspected var : " + cpp2::to_string(fun(var))) + "" << std::endl;
+    std::cout << "" + ("inspected myt : " + cpp2::to_string(fun(myt))) + "" << std::endl;
+
+    std::cout << "" + ("inspected vec : " + cpp2::to_string(fun2(cpp2::move(vec)))) + "" << std::endl;
+    std::cout << "" + ("inspected arr : " + cpp2::to_string(fun2(cpp2::move(arr)))) + "" << std::endl;
+    std::cout << "" + ("inspected var : " + cpp2::to_string(fun2(cpp2::move(var)))) + "" << std::endl;
+    std::cout << "" + ("inspected myt : " + cpp2::to_string(fun2(cpp2::move(myt)))) + "" << std::endl;
 }
 
diff --git a/regression-tests/test-results/mixed-string-interpolation.cpp b/regression-tests/test-results/mixed-string-interpolation.cpp
@@ -29,47 +29,47 @@ struct custom_struct_with_no_stringize_customization { } custom;
 [[nodiscard]] auto main() -> int{
     auto a {2}; 
     std::optional<int> b {}; 
-    std::cout << ("a = " + cpp2::to_string(a) + ", b = " + cpp2::to_string(b) + "\n");
+    std::cout << "" + ("a = " + cpp2::to_string(a) + ", b = " + cpp2::to_string(b) + "\n") + "";
 
     b = 42;
-    std::cout << ("a^2 + b = " + cpp2::to_string(a * a + CPP2_UFCS(value)(cpp2::move(b))) + "\n");
+    std::cout << "" + ("a^2 + b = " + cpp2::to_string(a * a + CPP2_UFCS(value)(cpp2::move(b))) + "\n") + "";
 
     std::string_view sv {"my string_view"}; 
-    std::cout << ("sv = " + cpp2::to_string(cpp2::move(sv)) + "\n");
+    std::cout << "" + ("sv = " + cpp2::to_string(cpp2::move(sv)) + "\n") + "";
 
     std::optional<std::string_view> osv {}; 
-    std::cout << ("osv = " + cpp2::to_string(osv) + "\n");
+    std::cout << "" + ("osv = " + cpp2::to_string(osv) + "\n") + "";
     osv = "string literal bound to optional string_view";
-    std::cout << ("osv = " + cpp2::to_string(cpp2::move(osv)) + "\n");
+    std::cout << "" + ("osv = " + cpp2::to_string(cpp2::move(osv)) + "\n") + "";
 
     std::variant<std::monostate,std::string,double> var {}; 
-    std::cout << ("var = " + cpp2::to_string(var) + "\n");
+    std::cout << "" + ("var = " + cpp2::to_string(var) + "\n") + "";
     var = "abracadabra";
-    std::cout << ("var = " + cpp2::to_string(var) + "\n");
+    std::cout << "" + ("var = " + cpp2::to_string(var) + "\n") + "";
     var = 2.71828;
-    std::cout << ("var = " + cpp2::to_string(cpp2::move(var)) + "\n");
+    std::cout << "" + ("var = " + cpp2::to_string(cpp2::move(var)) + "\n") + "";
 
     std::pair<int,double> mypair {12, 3.4}; 
-    std::cout << ("mypair = " + cpp2::to_string(cpp2::move(mypair)) + "\n");
+    std::cout << "" + ("mypair = " + cpp2::to_string(cpp2::move(mypair)) + "\n") + "";
 
     std::tuple<int> tup1 {12}; 
     std::tuple<int,double> tup2 {12, 3.4}; 
     std::tuple<int,double,std::string> tup3 {12, 3.4, "456"}; 
-    std::cout << ("tup1 = " + cpp2::to_string(cpp2::move(tup1)) + "\n");
-    std::cout << ("tup2 = " + cpp2::to_string(cpp2::move(tup2)) + "\n");
-    std::cout << ("tup3 = " + cpp2::to_string(cpp2::move(tup3)) + "\n");
+    std::cout << "" + ("tup1 = " + cpp2::to_string(cpp2::move(tup1)) + "\n") + "";
+    std::cout << "" + ("tup2 = " + cpp2::to_string(cpp2::move(tup2)) + "\n") + "";
+    std::cout << "" + ("tup3 = " + cpp2::to_string(cpp2::move(tup3)) + "\n") + "";
 
     std::pair<std::string_view,std::optional<std::string>> p {"first", std::nullopt}; 
-    std::cout << ("p = " + cpp2::to_string(cpp2::move(p)) + "\n");
+    std::cout << "" + ("p = " + cpp2::to_string(cpp2::move(p)) + "\n") + "";
 
     std::tuple<double,std::optional<std::pair<std::string_view,int>>,std::optional<std::tuple<int,int,int>>> t {3.14, std::nullopt, std::nullopt}; 
-    std::cout << ("t = " + cpp2::to_string(cpp2::move(t)) + "\n");
+    std::cout << "" + ("t = " + cpp2::to_string(cpp2::move(t)) + "\n") + "";
 
     std::variant<int,std::string,std::pair<int,double>> vv {}; 
-    std::cout << ("vv = " + cpp2::to_string(vv) + "\n");
+    std::cout << "" + ("vv = " + cpp2::to_string(vv) + "\n") + "";
     vv = std::make_pair(1, 2.3);
-    std::cout << ("vv = " + cpp2::to_string(cpp2::move(vv)) + "\n");
+    std::cout << "" + ("vv = " + cpp2::to_string(cpp2::move(vv)) + "\n") + "";
 
-    std::cout << ("custom = " + cpp2::to_string(custom) + "\n");
+    std::cout << "" + ("custom = " + cpp2::to_string(custom) + "\n") + "";
 }
 
diff --git a/regression-tests/test-results/mixed-test-parens.cpp b/regression-tests/test-results/mixed-test-parens.cpp
@@ -32,7 +32,7 @@ constexpr int a = 1;
 
     std::vector<int> v {1, 2, 3}; 
     std::cout << (1 + 2) * (3 + CPP2_ASSERT_IN_BOUNDS_LITERAL(cpp2::move(v), 0));
-    std::cout << ("\n13*14 is " + cpp2::to_string(13 * 14) + "\n");
+    std::cout << "" + ("\n13*14 is " + cpp2::to_string(13 * 14) + "\n") + "";
     f<(cpp2::impl::cmp_greater(1,2))>(3, 4);
     f<a + a>(5, 6);
 }

diff --git a/regression-tests/test-results/pure2-bugfix-for-template-argument.cpp b/regression-tests/test-results/pure2-bugfix-for-template-argument.cpp
@@ -19,5 +19,5 @@ auto main() -> int;
 #line 1 "pure2-bugfix-for-template-argument.cpp2"
 auto main() -> int { 
 #line 2 "pure2-bugfix-for-template-argument.cpp2"
-    std::cout << (cpp2::to_string(std::is_void_v<cpp2::i32*> && std::is_void_v<cpp2::i32 const>) + "\n");  }
+    std::cout << "" + (cpp2::to_string(std::is_void_v<cpp2::i32*> && std::is_void_v<cpp2::i32 const>) + "\n") + "";  }
 
diff --git a/regression-tests/test-results/pure2-contracts.cpp b/regression-tests/test-results/pure2-contracts.cpp
@@ -43,7 +43,7 @@ auto main() -> int{
     if (cpp2::type_safety.is_active() && !(test_condition_evaluation(2)) ) { cpp2::type_safety.report_violation(CPP2_CONTRACT_MSG("type")); }// evaluated: prints "2"
     CPP2_UFCS(set_handler)(cpp2::type_safety);
     //  Type does not have a handler
-    if (cpp2::type_safety.is_active() && !(test_condition_evaluation(3)) ) { cpp2::type_safety.report_violation(CPP2_CONTRACT_MSG(("1 == " + cpp2::to_string(1)))); }// not evaluated
+    if (cpp2::type_safety.is_active() && !(test_condition_evaluation(3)) ) { cpp2::type_safety.report_violation(CPP2_CONTRACT_MSG("" + ("1 == " + cpp2::to_string(1)) + "")); }// not evaluated
 
     //  Bounds has a handler, and audit is true
     if (audit && cpp2::bounds_safety.is_active() && !(test_condition_evaluation(4)) ) { cpp2::bounds_safety.report_violation(CPP2_CONTRACT_MSG("type")); }// evaluated: prints "4"

diff --git a/regression-tests/test-results/pure2-enum.cpp b/regression-tests/test-results/pure2-enum.cpp
@@ -255,8 +255,8 @@ auto main() -> int{
     // if x == 9 { }                    // error, can't compare skat_game and integer
     // if x == rgb::red { }             // error, can't compare skat_game and rgb color
 
-    std::cout << ("x.to_string() is " + cpp2::to_string(CPP2_UFCS(to_string)(x)) + "\n");
-    std::cout << ("x2.to_string() is " + cpp2::to_string(CPP2_UFCS(to_string)(cpp2::move(x2))) + "\n");
+    std::cout << "" + ("x.to_string() is " + cpp2::to_string(CPP2_UFCS(to_string)(x)) + "\n") + "";
+    std::cout << "" + ("x2.to_string() is " + cpp2::to_string(CPP2_UFCS(to_string)(cpp2::move(x2))) + "\n") + "";
 
     std::cout << "with if else: ";
     if (x == skat_game::diamonds) {     // ok, can compare two skat_games
@@ -288,17 +288,17 @@ auto main() -> int{
 
     x = skat_game::diamonds;        // ok, can assign one skat_game from another
 
-    std::cout << ("file_attributes::cached.get_raw_value() is " + cpp2::to_string(CPP2_UFCS(get_raw_value)(file_attributes::cached)) + "\n");
-    std::cout << ("file_attributes::current.get_raw_value() is " + cpp2::to_string(CPP2_UFCS(get_raw_value)(file_attributes::current)) + "\n");
-    std::cout << ("file_attributes::obsolete.get_raw_value() is " + cpp2::to_string(CPP2_UFCS(get_raw_value)(file_attributes::obsolete)) + "\n");
-    std::cout << ("file_attributes::cached_and_current.get_raw_value() is " + cpp2::to_string(CPP2_UFCS(get_raw_value)(file_attributes::cached_and_current)) + "\n");
+    std::cout << "" + ("file_attributes::cached.get_raw_value() is " + cpp2::to_string(CPP2_UFCS(get_raw_value)(file_attributes::cached)) + "\n") + "";
+    std::cout << "" + ("file_attributes::current.get_raw_value() is " + cpp2::to_string(CPP2_UFCS(get_raw_value)(file_attributes::current)) + "\n") + "";
+    std::cout << "" + ("file_attributes::obsolete.get_raw_value() is " + cpp2::to_string(CPP2_UFCS(get_raw_value)(file_attributes::obsolete)) + "\n") + "";
+    std::cout << "" + ("file_attributes::cached_and_current.get_raw_value() is " + cpp2::to_string(CPP2_UFCS(get_raw_value)(file_attributes::cached_and_current)) + "\n") + "";
 
     file_attributes f {file_attributes::cached_and_current}; 
     f &= file_attributes::cached | file_attributes::obsolete;
-    std::cout << ("f. get_raw_value() is " + cpp2::to_string(CPP2_UFCS(get_raw_value)(f)) + "\n");
+    std::cout << "" + ("f. get_raw_value() is " + cpp2::to_string(CPP2_UFCS(get_raw_value)(f)) + "\n") + "";
 
     auto f2 {file_attributes::cached}; 
-    std::cout << ("f2.get_raw_value() is " + cpp2::to_string(CPP2_UFCS(get_raw_value)(f2)) + "\n");
+    std::cout << "" + ("f2.get_raw_value() is " + cpp2::to_string(CPP2_UFCS(get_raw_value)(f2)) + "\n") + "";
 
     std::cout << "f  is " << CPP2_UFCS(to_string)(f) << "\n";
     std::cout << "f2 is " << CPP2_UFCS(to_string)(f2) << "\n";
@@ -308,11 +308,11 @@ auto main() -> int{
     CPP2_UFCS(set)(f2, file_attributes::cached);
     std::cout << "f2 is " << CPP2_UFCS(to_string)(f2) << "\n";
 
-    std::cout << ("f. get_raw_value() is " + cpp2::to_string(CPP2_UFCS(get_raw_value)(f)) + "\n");
-    std::cout << ("f2.get_raw_value() is " + cpp2::to_string(CPP2_UFCS(get_raw_value)(f2)) + "\n");
+    std::cout << "" + ("f. get_raw_value() is " + cpp2::to_string(CPP2_UFCS(get_raw_value)(f)) + "\n") + "";
+    std::cout << "" + ("f2.get_raw_value() is " + cpp2::to_string(CPP2_UFCS(get_raw_value)(f2)) + "\n") + "";
 
-    std::cout << ("f  is (f2) is " + cpp2::to_string(cpp2::impl::is(f, (f2))) + "\n");
-    std::cout << ("f2 is (f ) is " + cpp2::to_string(cpp2::impl::is(f2, (f))) + "\n\n");
+    std::cout << "" + ("f  is (f2) is " + cpp2::to_string(cpp2::impl::is(f, (f2))) + "\n") + "";
+    std::cout << "" + ("f2 is (f ) is " + cpp2::to_string(cpp2::impl::is(f2, (f))) + "\n\n") + "";
 
     CPP2_UFCS(clear)(f, f2);
     CPP2_UFCS(set)(f, file_attributes::current | f2);
@@ -321,12 +321,12 @@ auto main() -> int{
 
     std::cout << "f  is " << CPP2_UFCS(to_string)(f) << "\n";
     std::cout << "f2 is " << CPP2_UFCS(to_string)(f2) << "\n";
-    std::cout << ("f. get_raw_value() is " + cpp2::to_string(CPP2_UFCS(get_raw_value)(f)) + "\n");
-    std::cout << ("f2.get_raw_value() is " + cpp2::to_string(CPP2_UFCS(get_raw_value)(f2)) + "\n");
-    std::cout << ("f  == f2   is " + cpp2::to_string(f  == f2  ) + "\n");
-    std::cout << ("f  is (f2) is " + cpp2::to_string(cpp2::impl::is(f, (f2))) + "\n");
-    std::cout << ("f2 is (f ) is " + cpp2::to_string(cpp2::impl::is(f2, (f))) + "\n");
-    std::cout << ("(f & f2) == f2 is " + cpp2::to_string((f & f2) == f2) + "\n");
+    std::cout << "" + ("f. get_raw_value() is " + cpp2::to_string(CPP2_UFCS(get_raw_value)(f)) + "\n") + "";
+    std::cout << "" + ("f2.get_raw_value() is " + cpp2::to_string(CPP2_UFCS(get_raw_value)(f2)) + "\n") + "";
+    std::cout << "" + ("f  == f2   is " + cpp2::to_string(f  == f2  ) + "\n") + "";
+    std::cout << "" + ("f  is (f2) is " + cpp2::to_string(cpp2::impl::is(f, (f2))) + "\n") + "";
+    std::cout << "" + ("f2 is (f ) is " + cpp2::to_string(cpp2::impl::is(f2, (f))) + "\n") + "";
+    std::cout << "" + ("(f & f2) == f2 is " + cpp2::to_string((f & f2) == f2) + "\n") + "";
 
     std::cout << "inspecting f: " << [&] () -> std::string { auto&& _expr = cpp2::move(f);
         if (cpp2::impl::is(_expr, (file_attributes::current))) { if constexpr( requires{"exactly 'current'";} ) if constexpr( std::is_convertible_v<CPP2_TYPEOF(("exactly 'current'")),std::string> ) return "exactly 'current'"; else return std::string{}; else return std::string{}; }

diff --git a/regression-tests/test-results/pure2-interpolation.cpp b/regression-tests/test-results/pure2-interpolation.cpp
@@ -46,16 +46,16 @@ auto const& x{0};
 
 #line 11 "pure2-interpolation.cpp2"
     {
-        std::cout << ("g" + cpp2::to_string(x) + "g" + cpp2::to_string(x) + "g")  << "\n";
-        std::cout << (cpp2::to_string(x) + "g" + cpp2::to_string(x) + "g")   << "\n";
-        std::cout << (cpp2::to_string(x) + "g" + cpp2::to_string(x))    << "\n";
-        std::cout << (cpp2::to_string(x) + cpp2::to_string(x))     << "\n";
-        std::cout << ("\"" + cpp2::to_string(x) + "\"")     << "\n";
-        std::cout << ("\"" + cpp2::to_string(x))       << "\n";
+        std::cout << "" + ("g" + cpp2::to_string(x) + "g" + cpp2::to_string(x) + "g") + "" << "\n";
+        std::cout << "" + (cpp2::to_string(x) + "g" + cpp2::to_string(x) + "g") + ""  << "\n";
+        std::cout << "" + (cpp2::to_string(x) + "g" + cpp2::to_string(x)) + ""   << "\n";
+        std::cout << "" + (cpp2::to_string(x) + cpp2::to_string(x)) + ""    << "\n";
+        std::cout << "" + ("\"" + cpp2::to_string(x) + "\"") + ""    << "\n";
+        std::cout << "" + ("\"" + cpp2::to_string(x)) + ""      << "\n";
         std::cout << "\""           << "\n";
         std::cout << ""             << "\n";
         std::cout << "pl(ug$h"      << "\n";
-        std::cout << (cpp2::to_string(x) + "pl(ug$h")  << "\n";
+        std::cout << "" + (cpp2::to_string(x) + "pl(ug$h") + "" << "\n";
 
     }
 }
@@ -66,13 +66,13 @@ auto const& x{item()};
     {
         std::cout << std::left << std::setw(20) << CPP2_UFCS(name)(x) << " color " << std::left << std::setw(10) << CPP2_UFCS(color)(x) << " price " << std::setw(10) << std::setprecision(3) << CPP2_UFCS(price)(x) << " in stock = " << std::boolalpha << (cpp2::impl::cmp_greater(CPP2_UFCS(count)(x),0)) << "\n";
 
-        std::cout << (cpp2::to_string(CPP2_UFCS(name)(x), "{:20}") + " color " + cpp2::to_string(CPP2_UFCS(color)(x), "{:10}") + " price " + cpp2::to_string(CPP2_UFCS(price)(x), "{: <10.2f}") + " in stock = " + cpp2::to_string(cpp2::impl::cmp_greater(CPP2_UFCS(count)(x),0)) + "\n");
+        std::cout << "" + (cpp2::to_string(CPP2_UFCS(name)(x), "{:20}") + " color " + cpp2::to_string(CPP2_UFCS(color)(x), "{:10}") + " price " + cpp2::to_string(CPP2_UFCS(price)(x), "{: <10.2f}") + " in stock = " + cpp2::to_string(cpp2::impl::cmp_greater(CPP2_UFCS(count)(x),0)) + "\n") + "";
     }
 }
 
 #line 31 "pure2-interpolation.cpp2"
     std::complex ri {1.2, 3.4}; 
-    std::cout << ("complex: " + cpp2::to_string(cpp2::move(ri)) + "\n");// works on GCC 11.2+ and Clang 13+
+    std::cout << "" + ("complex: " + cpp2::to_string(cpp2::move(ri)) + "\n") + "";// works on GCC 11.2+ and Clang 13+
                                         // prints "customize me" on GCC 11.1 and Clang 12
 }
 
diff --git a/regression-tests/test-results/pure2-is-with-free-functions-predicate.cpp b/regression-tests/test-results/pure2-is-with-free-functions-predicate.cpp
@@ -32,15 +32,15 @@ auto fun(auto const& v) -> void;
 auto fun(auto const& v) -> void{
 #line 2 "pure2-is-with-free-functions-predicate.cpp2"
     if (cpp2::impl::is(v, (pred_i))) {
-        std::cout << (cpp2::to_string(v) + " is integer bigger than 3") << std::endl;
+        std::cout << "" + (cpp2::to_string(v) + " is integer bigger than 3") + "" << std::endl;
     }
 
     if (cpp2::impl::is(v, (pred_d))) {
-        std::cout << (cpp2::to_string(v) + " is double bigger than 3") << std::endl;
+        std::cout << "" + (cpp2::to_string(v) + " is double bigger than 3") + "" << std::endl;
     }
 
     if (cpp2::impl::is(v, (pred_))) {
-        std::cout << (cpp2::to_string(v) + " is bigger than 3") << std::endl;
+        std::cout << "" + (cpp2::to_string(v) + " is bigger than 3") + "" << std::endl;
     }
 }
 

diff --git a/regression-tests/test-results/pure2-is-with-unnamed-predicates.cpp b/regression-tests/test-results/pure2-is-with-unnamed-predicates.cpp
@@ -23,15 +23,15 @@ auto fun(auto const& v) -> void;
 auto fun(auto const& v) -> void{
 #line 2 "pure2-is-with-unnamed-predicates.cpp2"
     if (cpp2::impl::is(v, ([](cpp2::impl::in<int> x) mutable -> auto { return cpp2::impl::cmp_greater(x,3); }))) {
-        std::cout << (cpp2::to_string(v) + " is integer bigger than 3") << std::endl;
+        std::cout << "" + (cpp2::to_string(v) + " is integer bigger than 3") + "" << std::endl;
     }
 
     if (cpp2::impl::is(v, ([](cpp2::impl::in<double> x) mutable -> auto { return cpp2::impl::cmp_greater(x,3); }))) {
-        std::cout << (cpp2::to_string(v) + " is double bigger than 3") << std::endl;
+        std::cout << "" + (cpp2::to_string(v) + " is double bigger than 3") + "" << std::endl;
     }
 
     if (cpp2::impl::is(v, ([](auto const& x) mutable -> auto { return cpp2::impl::cmp_greater(x,3); }))) {
-        std::cout << (cpp2::to_string(v) + " is bigger than 3") << std::endl;
+        std::cout << "" + (cpp2::to_string(v) + " is bigger than 3") + "" << std::endl;
     }
 }
 

diff --git a/regression-tests/test-results/pure2-last-use.cpp b/regression-tests/test-results/pure2-last-use.cpp
@@ -1298,7 +1298,7 @@ auto const& x{cpp2_new<int>(0)};
 #line 790 "pure2-last-use.cpp2"
 auto issue_962(cpp2::impl::in<::std::string> s) -> void{
   using ::std::string;
-  std::cout << ("A: " + cpp2::to_string(s)) << std::endl;
+  std::cout << "" + ("A: " + cpp2::to_string(s)) + "" << std::endl;
 }
 
 #line 795 "pure2-last-use.cpp2"

diff --git a/regression-tests/test-results/pure2-main-args.cpp b/regression-tests/test-results/pure2-main-args.cpp
@@ -26,8 +26,8 @@ auto main(int const argc_, char** argv_) -> int{
 #line 6 "pure2-main-args.cpp2"
     auto exe {CPP2_UFCS(string)(CPP2_UFCS(filename)(std::filesystem::path(CPP2_ASSERT_IN_BOUNDS_LITERAL(args.argv, 0))))}; 
     std::cout 
-        << ("args.argc            is " + cpp2::to_string(args.argc) + "\n") 
-        << ("args.argv[0]         is " + cpp2::to_string(cpp2::move(exe)) + "\n");
+        << "" + ("args.argc            is " + cpp2::to_string(args.argc) + "\n") + "" 
+        << "" + ("args.argv[0]         is " + cpp2::to_string(cpp2::move(exe)) + "\n") + "";
 
 }
 
diff --git a/regression-tests/test-results/pure2-print.cpp b/regression-tests/test-results/pure2-print.cpp
@@ -121,7 +121,7 @@ requires (true) inline CPP2_CONSTEXPR T outer::object_alias{ 42 };
 #line 36 "pure2-print.cpp2"
         {
             if (cpp2::cpp2_default.is_active() && !(CPP2_UFCS(empty)(m) == false || false) ) { cpp2::cpp2_default.report_violation(CPP2_CONTRACT_MSG("message")); }
-            if (testing_enabled && cpp2::bounds_safety.is_active() && !([_0 = 0, _1 = CPP2_UFCS(ssize)(m), _2 = 100]{ return cpp2::impl::cmp_less(_0,_1) && cpp2::impl::cmp_less(_1,_2); }() && true != false) ) { cpp2::bounds_safety.report_violation(CPP2_CONTRACT_MSG(("size is " + cpp2::to_string(CPP2_UFCS(ssize)(m))))); }
+            if (testing_enabled && cpp2::bounds_safety.is_active() && !([_0 = 0, _1 = CPP2_UFCS(ssize)(m), _2 = 100]{ return cpp2::impl::cmp_less(_0,_1) && cpp2::impl::cmp_less(_1,_2); }() && true != false) ) { cpp2::bounds_safety.report_violation(CPP2_CONTRACT_MSG("" + ("size is " + cpp2::to_string(CPP2_UFCS(ssize)(m))) + "")); }
 #line 37 "pure2-print.cpp2"
             auto a {[]() mutable -> void{}}; 
             auto b {[]() mutable -> void{}}; 

diff --git a/regression-tests/test-results/pure2-print.cpp2.output b/regression-tests/test-results/pure2-print.cpp2.output
@@ -33,7 +33,7 @@ outer:/* @print */ type =
             inout m: std::map<const int, std::string>, 
         ) -> move std::string
             pre( m.empty() == false || false, "message" )
-            pre<bounds_safety,testing_enabled>( 0 < m.ssize() < 100 && true != false, ("size is " + cpp2::to_string(m.ssize())) ) = 
+            pre<bounds_safety,testing_enabled>( 0 < m.ssize() < 100 && true != false, "" + ("size is " + cpp2::to_string(m.ssize())) + "" ) = 
         {
             a: _ = :() = 
                 {