Change printing requires clauses in all phases

This change use the same rules for all printer phases and prints
`CPP2_REQUIRES_` or `CPP2_REQUIRES`

Author: filipsajdak

regression-tests/test-results/gcc-10-c++20/mixed-increment-decrement.cpp.output

@@ -6,11 +6,7 @@ mixed-increment-decrement.cpp2:4:39: error: expected ‘;’ at end of member de
 In file included from mixed-increment-decrement.cpp:6:
 ../../../include/cpp2util.h:10005:47: error: static assertion failed: GCC 11 or higher is required to support variables and type-scope functions that have a 'requires' clause. This includes a type-scope 'forward' parameter of non-wildcard type, such as 'func: (this, forward s: std::string)', which relies on being able to add a 'requires' clause - in that case, use 'forward s: _' instead if you need the result to compile with GCC 10.
 mixed-increment-decrement.cpp2:5:1: note: in expansion of macro ‘CPP2_REQUIRES_’
-mixed-increment-decrement.cpp2:4:32: error: no declaration matches ‘iterator<T>& iterator<T>::operator++() & requires  true’
-mixed-increment-decrement.cpp2:4:18: note: candidates are: ‘iterator<T> iterator<T>::operator++(int) &’
-mixed-increment-decrement.cpp2:4:18: note:                 ‘iterator<T>& iterator<T>::operator++() &’
-mixed-increment-decrement.cpp2:2:28: note: ‘class iterator<T>’ defined here
-mixed-increment-decrement.cpp2:4:32: error: no declaration matches ‘iterator<T> iterator<T>::operator++(int) & requires  true’
-mixed-increment-decrement.cpp2:4:18: note: candidates are: ‘iterator<T> iterator<T>::operator++(int) &’
-mixed-increment-decrement.cpp2:4:18: note:                 ‘iterator<T>& iterator<T>::operator++() &’
-mixed-increment-decrement.cpp2:2:28: note: ‘class iterator<T>’ defined here
+../../../include/cpp2util.h:10005:33: error: expected initializer before ‘static_assert’
+mixed-increment-decrement.cpp2:5:1: note: in expansion of macro ‘CPP2_REQUIRES_’
+../../../include/cpp2util.h:10005:33: error: expected initializer before ‘static_assert’
+mixed-increment-decrement.cpp2:5:1: note: in expansion of macro ‘CPP2_REQUIRES_’

regression-tests/test-results/gcc-10-c++20/mixed-type-safety-1.cpp.execution

@@ -0,0 +1,6 @@
+1.1 is int? 0
+1   is int? 1
+
+s* is Shape?  1
+s* is Circle? true
+s* is Square? false

regression-tests/test-results/gcc-10-c++20/pure2-bugfix-for-requires-clause-in-forward-declaration.cpp.output

@@ -6,12 +6,9 @@ pure2-bugfix-for-requires-clause-in-forward-declaration.cpp2:3:46: error: expect
 In file included from pure2-bugfix-for-requires-clause-in-forward-declaration.cpp:7:
 ../../../include/cpp2util.h:10005:47: error: static assertion failed: GCC 11 or higher is required to support variables and type-scope functions that have a 'requires' clause. This includes a type-scope 'forward' parameter of non-wildcard type, such as 'func: (this, forward s: std::string)', which relies on being able to add a 'requires' clause - in that case, use 'forward s: _' instead if you need the result to compile with GCC 10.
 pure2-bugfix-for-requires-clause-in-forward-declaration.cpp2:4:1: note: in expansion of macro ‘CPP2_REQUIRES_’
-pure2-bugfix-for-requires-clause-in-forward-declaration.cpp2:3:3: error: no declaration matches ‘element::element(auto:95&&) requires  is_same_v<std::__cxx11::string, typename std::remove_cv<typename std::remove_reference<decltype(element::__ct ::n)>::type>::type>’
-pure2-bugfix-for-requires-clause-in-forward-declaration.cpp2:5:11: note: candidates are: ‘element::element(const element&)’
-pure2-bugfix-for-requires-clause-in-forward-declaration.cpp2:3:20: note:                 ‘template<class auto:93> element::element(auto:93&&)’
-pure2-bugfix-for-requires-clause-in-forward-declaration.cpp2:1:7: note: ‘class element’ defined here
+../../../include/cpp2util.h:10005:33: error: expected initializer before ‘static_assert’
+pure2-bugfix-for-requires-clause-in-forward-declaration.cpp2:4:1: note: in expansion of macro ‘CPP2_REQUIRES_’
 pure2-bugfix-for-requires-clause-in-forward-declaration.cpp2:5:78: error: expected unqualified-id before ‘{’ token
-pure2-bugfix-for-requires-clause-in-forward-declaration.cpp2:3:8: error: no declaration matches ‘element& element::operator=(auto:96&&) requires  is_same_v<std::__cxx11::string, typename std::remove_cv<typename std::remove_reference<decltype(element::operator=::n)>::type>::type>’
-pure2-bugfix-for-requires-clause-in-forward-declaration.cpp2:6:16: note: candidates are: ‘void element::operator=(const element&)’
-pure2-bugfix-for-requires-clause-in-forward-declaration.cpp2:3:16: note:                 ‘template<class auto:94> element& element::operator=(auto:94&&)’
-pure2-bugfix-for-requires-clause-in-forward-declaration.cpp2:1:7: note: ‘class element’ defined here
+In file included from pure2-bugfix-for-requires-clause-in-forward-declaration.cpp:7:
+../../../include/cpp2util.h:10005:33: error: expected initializer before ‘static_assert’
+pure2-bugfix-for-requires-clause-in-forward-declaration.cpp2:4:1: note: in expansion of macro ‘CPP2_REQUIRES_’

regression-tests/test-results/gcc-10-c++20/pure2-print.cpp.output

@@ -7,11 +7,9 @@ In file included from pure2-print.cpp:7:
 pure2-print.cpp2:68:1: note: in expansion of macro ‘CPP2_REQUIRES_’
 ../../../include/cpp2util.h:10005:33: error: expected initializer before ‘static_assert’
 pure2-print.cpp2:97:1: note: in expansion of macro ‘CPP2_REQUIRES_’
-pure2-print.cpp2:9:41: error: ‘constexpr const T outer::object_alias’ is not a static data member of ‘class outer’
-pure2-print.cpp2:9:48: error: template definition of non-template ‘constexpr const T outer::object_alias’
-pure2-print.cpp2:67:14: error: no declaration matches ‘void outer::mytype::variadic(const auto:94& ...) requires (is_convertible_v<typename std::remove_cv<typename std::remove_reference<decltype(outer::mytype::variadic::x)>::type>::type, int> && ...)’
-pure2-print.cpp2:67:29: note: candidate is: ‘template<class ... auto:93> static void outer::mytype::variadic(const auto:93& ...)’
-pure2-print.cpp2:10:19: note: ‘class outer::mytype’ defined here
-pure2-print.cpp2:96:37: error: no declaration matches ‘void outer::print(std::ostream&, const Args& ...) requires  cpp2::impl::cmp_greater_eq(sizeof ... (Args ...), 0)’
-pure2-print.cpp2:96:37: note: no functions named ‘void outer::print(std::ostream&, const Args& ...) requires  cpp2::impl::cmp_greater_eq(sizeof ... (Args ...), 0)’
-pure2-print.cpp2:6:7: note: ‘class outer’ defined here
+../../../include/cpp2util.h:10005:33: error: expected unqualified-id before ‘static_assert’
+pure2-print.cpp2:9:1: note: in expansion of macro ‘CPP2_REQUIRES_’
+../../../include/cpp2util.h:10005:33: error: expected initializer before ‘static_assert’
+pure2-print.cpp2:68:1: note: in expansion of macro ‘CPP2_REQUIRES_’
+../../../include/cpp2util.h:10005:33: error: expected initializer before ‘static_assert’
+pure2-print.cpp2:97:1: note: in expansion of macro ‘CPP2_REQUIRES_’

regression-tests/test-results/gcc-10-c++20/pure2-requires-clauses.cpp.output

@@ -1,3 +1,5 @@
 In file included from pure2-requires-clauses.cpp:7:
 ../../../include/cpp2util.h:10005:33: error: expected unqualified-id before ‘static_assert’
 pure2-requires-clauses.cpp2:21:1: note: in expansion of macro ‘CPP2_REQUIRES_’
+../../../include/cpp2util.h:10005:33: error: expected unqualified-id before ‘static_assert’
+pure2-requires-clauses.cpp2:21:1: note: in expansion of macro ‘CPP2_REQUIRES_’

regression-tests/test-results/gcc-10-c++20/pure2-type-constraints.cpp.output

@@ -0,0 +1,2 @@
+pure2-type-constraints.cpp2:6:6: error: redefinition of ‘template<class auto:96> void print(const auto:96&)’
+pure2-type-constraints.cpp2:2:6: note: ‘template<class auto:93> void print(const auto:93&)’ previously declared here

regression-tests/test-results/mixed-increment-decrement.cpp

@@ -132,10 +132,10 @@ auto operator--(number_line_pre_decrement<1>& x,int) -> number_line_pre_decremen
 
 #line 4 "mixed-increment-decrement.cpp2"
     template <typename T> auto iterator<T>::operator++() & -> iterator<T>&
-CPP2_REQUIRES (true) {++x; return (*this); }
+CPP2_REQUIRES_ (true) {++x; return (*this); }
 #line 4 "mixed-increment-decrement.cpp2"
     template <typename T> auto iterator<T>::operator++(int) & -> iterator<T>
-CPP2_REQUIRES (true)  { auto ret = *this; ++*this; return ret; }
+CPP2_REQUIRES_ (true)  { auto ret = *this; ++*this; return ret; }
 
 
     template <typename T> iterator<T>::iterator(iterator const& that)

regression-tests/test-results/pure2-bugfix-for-requires-clause-in-forward-declaration.cpp

@@ -35,11 +35,11 @@ auto main() -> int;
 
 #line 3 "pure2-bugfix-for-requires-clause-in-forward-declaration.cpp2"
   element::element(auto&& n)
-CPP2_REQUIRES (std::is_same_v<std::string, CPP2_TYPEOF(n)>) 
+CPP2_REQUIRES_ (std::is_same_v<std::string, CPP2_TYPEOF(n)>) 
                                                     : name{ CPP2_FORWARD(n) }{}
 #line 3 "pure2-bugfix-for-requires-clause-in-forward-declaration.cpp2"
   auto element::operator=(auto&& n) -> element& 
-CPP2_REQUIRES (std::is_same_v<std::string, CPP2_TYPEOF(n)>) {
+CPP2_REQUIRES_ (std::is_same_v<std::string, CPP2_TYPEOF(n)>) {
                                                     name = CPP2_FORWARD(n);
                                                     return *this; }
 

regression-tests/test-results/pure2-print.cpp

@@ -89,7 +89,7 @@ bool testing_enabled {false};
 
 #line 8 "pure2-print.cpp2"
     template<typename T> 
-CPP2_REQUIRES (true) inline CPP2_CONSTEXPR T outer::object_alias{ 42 };
+CPP2_REQUIRES_ (true) inline CPP2_CONSTEXPR T outer::object_alias{ 42 };
 #line 9 "pure2-print.cpp2"
 
 #line 12 "pure2-print.cpp2"
@@ -163,7 +163,7 @@ CPP2_REQUIRES (true) inline CPP2_CONSTEXPR T outer::object_alias{ 42 };
 
 #line 67 "pure2-print.cpp2"
         auto outer::mytype::variadic(auto const& ...x) -> void
-CPP2_REQUIRES ((std::is_convertible_v<CPP2_TYPEOF(x), int> && ...)) {(std::cout << ... << x); }
+CPP2_REQUIRES_ ((std::is_convertible_v<CPP2_TYPEOF(x), int> && ...)) {(std::cout << ... << x); }
 
 #line 70 "pure2-print.cpp2"
     auto outer::test() -> void{
@@ -190,7 +190,7 @@ CPP2_REQUIRES ((std::is_convertible_v<CPP2_TYPEOF(x), int> && ...)) {(std::cout
 
 #line 96 "pure2-print.cpp2"
     template<typename ...Args> auto outer::print(std::ostream& out, Args const& ...args) -> void
-CPP2_REQUIRES (cpp2::impl::cmp_greater_eq(sizeof...(Args),0u)) {
+CPP2_REQUIRES_ (cpp2::impl::cmp_greater_eq(sizeof...(Args),0u)) {
 #line 97 "pure2-print.cpp2"
         (out << ... << args);
     }

regression-tests/test-results/pure2-requires-clauses.cpp

@@ -72,7 +72,7 @@ CPP2_REQUIRES (true)  { return x;  }
 
 #line 20 "pure2-requires-clauses.cpp2"
 template<typename T> 
-CPP2_REQUIRES (std::same_as<T,cpp2::i32>) T const v {0}; 
+CPP2_REQUIRES_ (std::same_as<T,cpp2::i32>) T const v {0}; 
 
 #line 22 "pure2-requires-clauses.cpp2"
 auto main() -> int{

source/to_cpp1.h

@@ -5601,15 +5601,8 @@ class cppfront
             {
                 printer.print_extra("\n");
                 printer.ignore_alignment( true, n.position().colno + 4 );
-                if (printer.get_phase() == printer.phase1_type_defs_func_decls) {
-                    // Workaround GCC 10 not supporting requires in forward declarations in some cases.
-                    // See commit 5a0d77f8e297902c0b9712c5aafb6208cfa4c139.
-                    if (n.is_object() || n.parent_is_type()) {
-                        printer.print_extra("CPP2_REQUIRES_ (");
-                    }
-                    else {
-                        printer.print_extra("CPP2_REQUIRES (");
-                    }
+                if (n.is_object() || n.parent_is_type()) {
+                    printer.print_extra("CPP2_REQUIRES_ (");
                 }
                 else {
                     printer.print_extra("CPP2_REQUIRES (");