Add std::source_location support when logging error information (#1185)

Author: dmachaj

strings/base_error.h

@@ -28,6 +28,10 @@
 #include <format>
 #endif
 
+#ifdef __cpp_lib_source_location
+#include <source_location>
+#endif
+
 #ifdef __cpp_lib_coroutine
 
 #include <coroutine>

strings/base_includes.h

@@ -54,3 +54,27 @@
 struct IUnknown;
 typedef struct _GUID GUID;
 #endif
+
+// std::source_location is a C++20 feature, which is above the C++17 feature floor for cppwinrt.  The source location needs
+// to be the calling code, not cppwinrt itself, so that it is useful to developers building on top of this library.  As a
+// result any public-facing method that can result in an error needs a default-constructed source_location argument.  Because
+// this type does not exist in C++17 we need to use a macro to optionally add parameters and forwarding wherever appropriate.
+#ifdef __cpp_lib_source_location
+#define WINRT_IMPL_SOURCE_LOCATION_ARGS_NO_DEFAULT , std::source_location const& sourceInformation
+#define WINRT_IMPL_SOURCE_LOCATION_ARGS , std::source_location const& sourceInformation = std::source_location::current()
+#define WINRT_IMPL_SOURCE_LOCATION_ARGS_SINGLE_PARAM std::source_location const& sourceInformation = std::source_location::current()
+
+#define WINRT_IMPL_SOURCE_LOCATION_FORWARD , sourceInformation
+#define WINRT_IMPL_SOURCE_LOCATION_FORWARD_SINGLE_PARAM sourceInformation
+
+#pragma detect_mismatch("WINRT_SOURCE_LOCATION", "true")
+#else
+#define WINRT_IMPL_SOURCE_LOCATION_ARGS_NO_DEFAULT
+#define WINRT_IMPL_SOURCE_LOCATION_ARGS
+#define WINRT_IMPL_SOURCE_LOCATION_ARGS_SINGLE_PARAM
+
+#define WINRT_IMPL_SOURCE_LOCATION_FORWARD
+#define WINRT_IMPL_SOURCE_LOCATION_FORWARD_SINGLE_PARAM
+
+#pragma detect_mismatch("WINRT_SOURCE_LOCATION", "false")
+#endif

strings/base_macros.h

@@ -1,7 +1,7 @@
 
 WINRT_EXPORT namespace winrt
 {
-    hresult check_hresult(hresult const result);
+    hresult check_hresult(hresult const result WINRT_IMPL_SOURCE_LOCATION_ARGS);
     hresult to_hresult() noexcept;
 
     template <typename D, typename I>

strings/base_meta.h

@@ -59,7 +59,11 @@ namespace
 
     void __stdcall logger(uint32_t lineNumber, char const* fileName, char const* functionName, void* returnAddress, winrt::hresult const result) noexcept
     {
-        lineNumber; fileName; functionName;
+        // In C++17 these fields cannot be filled in so they are expected to be empty.
+        REQUIRE(lineNumber == 0);
+        REQUIRE(fileName == nullptr);
+        REQUIRE(functionName == nullptr);
+
         REQUIRE(returnAddress);
         REQUIRE(result == 0x80000018); // E_ILLEGAL_DELEGATE_ASSIGNMENT)
         s_loggerCalled = true;

test/test/custom_error.cpp

@@ -0,0 +1,48 @@
+#include "pch.h"
+
+using namespace winrt;
+using namespace Windows::Foundation;
+
+namespace
+{
+    static bool s_loggerCalled = false;
+
+    // Note that we are checking that the source line number matches expectations.  If lines above this are changed
+    // then this value needs to change as well.
+    void FailOnLine15()
+    {
+        // Validate that handler translated exception
+        REQUIRE_THROWS_AS(check_hresult(0x80000018), hresult_illegal_delegate_assignment);
+    }
+
+    void __stdcall logger(uint32_t lineNumber, char const* fileName, char const* functionName, void* returnAddress, winrt::hresult const result) noexcept
+    {
+        // In C++20 these fields should be filled in by std::source_location
+        REQUIRE(lineNumber == 15);
+        const auto fileNameSv = std::string_view(fileName);
+        REQUIRE(!fileNameSv.empty());
+        REQUIRE(fileNameSv.find("custom_error.cpp") != std::string::npos);
+        const auto functionNameSv = std::string_view(functionName);
+        REQUIRE(!functionNameSv.empty());
+        REQUIRE(functionNameSv == "FailOnLine15");
+
+        REQUIRE(returnAddress);
+        REQUIRE(result == 0x80000018); // E_ILLEGAL_DELEGATE_ASSIGNMENT)
+        s_loggerCalled = true;
+    }
+}
+
+TEST_CASE("custom_error_logger")
+{
+    // Set up global handler
+    REQUIRE(!s_loggerCalled);
+    REQUIRE(!winrt_throw_hresult_handler);
+    winrt_throw_hresult_handler = logger;
+
+    FailOnLine15();
+    REQUIRE(s_loggerCalled);
+
+    // Remove global handler
+    winrt_throw_hresult_handler = nullptr;
+    s_loggerCalled = false;
+}

test/test_cpp20/custom_error.cpp

@@ -11,4 +11,6 @@
 #include <winstring.h>
 #include "catch.hpp"
 
+#include <string_view>
+
 using namespace std::literals;

test/test_cpp20/pch.h

@@ -281,6 +281,7 @@
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="await_completed.cpp" />
+    <ClCompile Include="custom_error.cpp" />
     <ClCompile Include="format.cpp" />
     <ClCompile Include="hstring.cpp" />
     <ClCompile Include="main.cpp">