test: add test case for discard precedence

Author: JohelEGP

regression-tests/pure2-bugfix-for-discard-precedence.cpp2

@@ -0,0 +1,16 @@
+quantity: type = {
+  number: i32;
+  operator=: (out this, _: std::in_place_t, x: i32) = {
+    number = x;
+    _      = _;
+  }
+  operator+=: (inout this, that) -> forward quantity = {
+    _ = number += that.number;
+    return this;
+  }
+}
+
+main: () = {
+  x: quantity = (std::in_place, 1729);
+  _ = x += x;
+}

regression-tests/test-results/clang-18/clang-version.output

@@ -0,0 +1,4 @@
+clang version 18.0.0 (https://git.uplinklabs.net/mirrors/llvm-project.git c0abd3814564a568dfc607c216e6407eaa314f46)
+Target: x86_64-pc-linux-gnu
+Thread model: posix
+InstalledDir: /home/johel/root/clang-main/bin

regression-tests/test-results/clang-18/pure2-bugfix-for-discard-precedence.cpp.output

@@ -0,0 +1,7 @@
+pure2-bugfix-for-discard-precedence.cpp2:8:19: error: invalid operands to binary expression ('void' and 'const cpp2::i32' (aka 'const int'))
+    8 |     (void) number += that.number;
+      |     ~~~~~~~~~~~~~ ^  ~~~~~~~~~~~
+pure2-bugfix-for-discard-precedence.cpp2:15:12: error: invalid operands to binary expression ('void' and '__libcpp_remove_reference_t<quantity &>' (aka 'quantity'))
+   15 |   (void) x += std::move(x);
+      |   ~~~~~~~~ ^  ~~~~~~~~~~~~
+2 errors generated.

regression-tests/test-results/pure2-bugfix-for-discard-precedence.cpp

@@ -0,0 +1,55 @@
+
+#define CPP2_USE_MODULES         Yes
+
+//=== Cpp2 type declarations ====================================================
+
+
+#include "cpp2util.h"
+
+#line 1 "pure2-bugfix-for-discard-precedence.cpp2"
+class quantity;
+  
+
+//=== Cpp2 type definitions and function declarations ===========================
+
+#line 1 "pure2-bugfix-for-discard-precedence.cpp2"
+class quantity {
+  private: cpp2::i32 number; 
+  public: explicit quantity(cpp2::in<std::in_place_t> _, cpp2::in<cpp2::i32> x);
+    
+
+#line 7 "pure2-bugfix-for-discard-precedence.cpp2"
+  public: [[nodiscard]] auto operator+=(quantity const& that) -> quantity&;
+    
+  public: quantity(quantity const&) = delete; /* No 'that' constructor, suppress copy */
+  public: auto operator=(quantity const&) -> void = delete;
+
+
+#line 11 "pure2-bugfix-for-discard-precedence.cpp2"
+};
+
+auto main() -> int;
+  
+
+//=== Cpp2 function definitions =================================================
+
+
+#line 3 "pure2-bugfix-for-discard-precedence.cpp2"
+  quantity::quantity(cpp2::in<std::in_place_t> _, cpp2::in<cpp2::i32> x)
+    : number{ x }
+#line 3 "pure2-bugfix-for-discard-precedence.cpp2"
+  {
+
+    (void)   _;
+  }
+  [[nodiscard]] auto quantity::operator+=(quantity const& that) -> quantity&{
+    (void) number += that.number;
+    return (*this); 
+  }
+
+#line 13 "pure2-bugfix-for-discard-precedence.cpp2"
+auto main() -> int{
+  quantity x {std::in_place, 1729}; 
+  (void) x += std::move(x);
+}
+

regression-tests/test-results/pure2-bugfix-for-discard-precedence.cpp2.output

@@ -0,0 +1,2 @@
+pure2-bugfix-for-discard-precedence.cpp2... ok (all Cpp2, passes safety checks)
+