Add tests for as casts that ends with static assert

* Add test for as cast to unrelated type
* Add test for as cast of arithetic types bigger to smaller
* Add test for as cast of bigger signed int to smaller unsigned
* Add test for as cast of double to int
* Add test for as cast of class to unrelated class
* Add test pure2-as-cast-custom-class-to-string

Author: filipsajdak

regression-tests/pure2-as-cast-arithetic-types-bigger-to-smaller.cpp2

@@ -0,0 +1,3 @@
+main: () = {
+    i := u16(12) as u8; // triggers static assert
+}

regression-tests/pure2-as-cast-bigger-signed-to-smaller-unsigned.cpp2

@@ -0,0 +1,3 @@
+main: () = {
+    i := i16(12) as  u8; // triggers static assert
+}

regression-tests/pure2-as-cast-class-to-unrelated-class.cpp2

@@ -0,0 +1,6 @@
+main: () = {
+    a := B() as A; // triggers static assert
+}
+
+A: type = {}
+B: type = {}

regression-tests/pure2-as-cast-custom-class-to-string.cpp2

@@ -0,0 +1,5 @@
+main: () = {
+    s := A() as std::string; // triggers static assert
+}
+
+A: type = {}

regression-tests/pure2-as-cast-double-to-int.cpp2

@@ -0,0 +1,3 @@
+main: () = {
+    i := 12.0 as int; // triggers static assert
+}

regression-tests/pure2-as-cast-to-unrelated-type.cpp2

@@ -0,0 +1,6 @@
+A: type = {}
+
+main: () = {
+    i := 42;
+    a := i as A; // triggers static assert
+}

regression-tests/test-results/apple-clang-14/pure2-as-cast-arithetic-types-bigger-to-smaller.cpp.output

@@ -0,0 +1,8 @@
+In file included from pure2-as-cast-arithetic-types-bigger-to-smaller.cpp:7:
+../../../include/cpp2util.h:1794:9: error: static_assert failed due to requirement 'program_violates_type_safety_guarantee<unsigned char, unsigned short &&>' "'as' does not allow unsafe narrowing conversions - if you're sure you want this, use `unsafe_narrow<T>()` to force the conversion"
+        static_assert(
+        ^
+pure2-as-cast-arithetic-types-bigger-to-smaller.cpp:19:19: note: in instantiation of function template specialization 'cpp2::as_<unsigned char, unsigned short>' requested here
+    auto i {cpp2::as_<cpp2::u8>(cpp2::u16(12))}; // triggers static assert
+                  ^
+1 error generated.

regression-tests/test-results/apple-clang-14/pure2-as-cast-bigger-signed-to-smaller-unsigned.cpp.output

@@ -0,0 +1,8 @@
+In file included from pure2-as-cast-bigger-signed-to-smaller-unsigned.cpp:7:
+../../../include/cpp2util.h:1794:9: error: static_assert failed due to requirement 'program_violates_type_safety_guarantee<unsigned char, short &&>' "'as' does not allow unsafe narrowing conversions - if you're sure you want this, use `unsafe_narrow<T>()` to force the conversion"
+        static_assert(
+        ^
+pure2-as-cast-bigger-signed-to-smaller-unsigned.cpp:19:19: note: in instantiation of function template specialization 'cpp2::as_<unsigned char, short>' requested here
+    auto i {cpp2::as_<cpp2::u8>(cpp2::i16(12))}; // triggers static assert
+                  ^
+1 error generated.

regression-tests/test-results/apple-clang-14/pure2-as-cast-class-to-unrelated-class.cpp.output

@@ -0,0 +1,8 @@
+In file included from pure2-as-cast-class-to-unrelated-class.cpp:7:
+../../../include/cpp2util.h:1800:9: error: static_assert failed due to requirement 'program_violates_type_safety_guarantee<A, B &&>' "No safe 'as' cast available - please check your cast"
+        static_assert(
+        ^
+pure2-as-cast-class-to-unrelated-class.cpp2:12:19: note: in instantiation of function template specialization 'cpp2::as_<A, B>' requested here
+    auto a {cpp2::as_<A>(B())}; // triggers static assert
+                  ^
+1 error generated.

regression-tests/test-results/apple-clang-14/pure2-as-cast-custom-class-to-string.cpp.output

@@ -0,0 +1,8 @@
+In file included from pure2-as-cast-custom-class-to-string.cpp:7:
+../../../include/cpp2util.h:1800:9: error: static_assert failed due to requirement 'program_violates_type_safety_guarantee<std::string, A &&>' "No safe 'as' cast available - please check your cast"
+        static_assert(
+        ^
+pure2-as-cast-custom-class-to-string.cpp2:11:19: note: in instantiation of function template specialization 'cpp2::as_<std::string, A>' requested here
+    auto s {cpp2::as_<std::string>(A())}; // triggers static assert
+                  ^
+1 error generated.

regression-tests/test-results/apple-clang-14/pure2-as-cast-double-to-int.cpp.output

@@ -0,0 +1,8 @@
+In file included from pure2-as-cast-double-to-int.cpp:7:
+../../../include/cpp2util.h:1794:9: error: static_assert failed due to requirement 'program_violates_type_safety_guarantee<int, double &&>' "'as' does not allow unsafe narrowing conversions - if you're sure you want this, use `unsafe_narrow<T>()` to force the conversion"
+        static_assert(
+        ^
+pure2-as-cast-double-to-int.cpp:19:19: note: in instantiation of function template specialization 'cpp2::as_<int, double>' requested here
+    auto i {cpp2::as_<int>(12.0)}; // triggers static assert
+                  ^
+1 error generated.

regression-tests/test-results/apple-clang-14/pure2-as-cast-to-unrelated-type.cpp.output

@@ -0,0 +1,8 @@
+In file included from pure2-as-cast-to-unrelated-type.cpp:7:
+../../../include/cpp2util.h:1800:9: error: static_assert failed due to requirement 'program_violates_type_safety_guarantee<A, int &>' "No safe 'as' cast available - please check your cast"
+        static_assert(
+        ^
+pure2-as-cast-to-unrelated-type.cpp2:5:19: note: in instantiation of function template specialization 'cpp2::as_<A, int &>' requested here
+    auto a {cpp2::as_<A>(i)}; // triggers static assert
+                  ^
+1 error generated.

regression-tests/test-results/pure2-as-cast-arithetic-types-bigger-to-smaller.cpp

@@ -0,0 +1,21 @@
+
+#define CPP2_USE_MODULES         Yes
+
+//=== Cpp2 type declarations ====================================================
+
+
+#include "cpp2util.h"
+
+
+
+//=== Cpp2 type definitions and function declarations ===========================
+
+auto main() -> int;
+    
+
+//=== Cpp2 function definitions =================================================
+
+auto main() -> int{
+    auto i {cpp2::as_<cpp2::u8>(cpp2::u16(12))}; // triggers static assert
+}
+

regression-tests/test-results/pure2-as-cast-arithetic-types-bigger-to-smaller.cpp2.output

@@ -0,0 +1,2 @@
+pure2-as-cast-arithetic-types-bigger-to-smaller.cpp2... ok (all Cpp2, passes safety checks)
+

regression-tests/test-results/pure2-as-cast-bigger-signed-to-smaller-unsigned.cpp

@@ -0,0 +1,21 @@
+
+#define CPP2_USE_MODULES         Yes
+
+//=== Cpp2 type declarations ====================================================
+
+
+#include "cpp2util.h"
+
+
+
+//=== Cpp2 type definitions and function declarations ===========================
+
+auto main() -> int;
+
+
+//=== Cpp2 function definitions =================================================
+
+auto main() -> int{
+    auto i {cpp2::as_<cpp2::u8>(cpp2::i16(12))}; // triggers static assert
+}
+

regression-tests/test-results/pure2-as-cast-bigger-signed-to-smaller-unsigned.cpp2.output

@@ -0,0 +1,2 @@
+pure2-as-cast-bigger-signed-to-smaller-unsigned.cpp2... ok (all Cpp2, passes safety checks)
+

regression-tests/test-results/pure2-as-cast-class-to-unrelated-class.cpp

@@ -0,0 +1,42 @@
+
+#define CPP2_USE_MODULES         Yes
+
+//=== Cpp2 type declarations ====================================================
+
+
+#include "cpp2util.h"
+
+
+#line 5 "pure2-as-cast-class-to-unrelated-class.cpp2"
+class A;
+class B;
+
+
+//=== Cpp2 type definitions and function declarations ===========================
+
+auto main() -> int;
+    
+
+#line 5 "pure2-as-cast-class-to-unrelated-class.cpp2"
+class A {
+      public: A() = default;
+      public: A(A const&) = delete; /* No 'that' constructor, suppress copy */
+      public: auto operator=(A const&) -> void = delete;
+
+#line 5 "pure2-as-cast-class-to-unrelated-class.cpp2"
+};
+class B {
+      public: B() = default;
+      public: B(B const&) = delete; /* No 'that' constructor, suppress copy */
+      public: auto operator=(B const&) -> void = delete;
+
+#line 6 "pure2-as-cast-class-to-unrelated-class.cpp2"
+};
+
+
+//=== Cpp2 function definitions =================================================
+
+auto main() -> int{
+    auto a {cpp2::as_<A>(B())}; // triggers static assert
+}
+

regression-tests/test-results/pure2-as-cast-class-to-unrelated-class.cpp2.output

@@ -0,0 +1,2 @@
+pure2-as-cast-class-to-unrelated-class.cpp2... ok (all Cpp2, passes safety checks)
+

regression-tests/test-results/pure2-as-cast-custom-class-to-string.cpp

@@ -0,0 +1,34 @@
+
+#define CPP2_USE_MODULES         Yes
+
+//=== Cpp2 type declarations ====================================================
+
+
+#include "cpp2util.h"
+
+
+#line 5 "pure2-as-cast-custom-class-to-string.cpp2"
+class A;
+
+
+//=== Cpp2 type definitions and function declarations ===========================
+
+auto main() -> int;
+    
+
+#line 5 "pure2-as-cast-custom-class-to-string.cpp2"
+class A {
+      public: A() = default;
+      public: A(A const&) = delete; /* No 'that' constructor, suppress copy */
+      public: auto operator=(A const&) -> void = delete;
+
+#line 5 "pure2-as-cast-custom-class-to-string.cpp2"
+};
+
+
+//=== Cpp2 function definitions =================================================
+
+auto main() -> int{
+    auto s {cpp2::as_<std::string>(A())}; // triggers static assert
+}
+

regression-tests/test-results/pure2-as-cast-custom-class-to-string.cpp2.output

@@ -0,0 +1,2 @@
+pure2-as-cast-custom-class-to-string.cpp2... ok (all Cpp2, passes safety checks)
+

regression-tests/test-results/pure2-as-cast-double-to-int.cpp

@@ -0,0 +1,21 @@
+
+#define CPP2_USE_MODULES         Yes
+
+//=== Cpp2 type declarations ====================================================
+
+
+#include "cpp2util.h"
+
+
+
+//=== Cpp2 type definitions and function declarations ===========================
+
+auto main() -> int;
+    
+
+//=== Cpp2 function definitions =================================================
+
+auto main() -> int{
+    auto i {cpp2::as_<int>(12.0)}; // triggers static assert
+}
+

regression-tests/test-results/pure2-as-cast-double-to-int.cpp2.output

@@ -0,0 +1,2 @@
+pure2-as-cast-double-to-int.cpp2... ok (all Cpp2, passes safety checks)
+

regression-tests/test-results/pure2-as-cast-to-unrelated-type.cpp

@@ -0,0 +1,31 @@
+
+#define CPP2_USE_MODULES         Yes
+
+//=== Cpp2 type declarations ====================================================
+
+
+#include "cpp2util.h"
+
+class A;
+
+
+//=== Cpp2 type definitions and function declarations ===========================
+
+class A {
+      public: A() = default;
+      public: A(A const&) = delete; /* No 'that' constructor, suppress copy */
+      public: auto operator=(A const&) -> void = delete;
+};
+
+auto main() -> int;
+    
+
+//=== Cpp2 function definitions =================================================
+
+
+#line 3 "pure2-as-cast-to-unrelated-type.cpp2"
+auto main() -> int{
+    auto i {42}; 
+    auto a {cpp2::as_<A>(i)}; // triggers static assert
+}
+

regression-tests/test-results/pure2-as-cast-to-unrelated-type.cpp2.output

@@ -0,0 +1,2 @@
+pure2-as-cast-to-unrelated-type.cpp2... ok (all Cpp2, passes safety checks)
+