[PATCH 0/1] MR9306: msvcrt: Use the correct arguments when a WinRT exception is thrown with _CxxThrowException.

[Vibhav Pant (＠vibhavp)]

Another dependency for !9209.

When C++/CX applications manually throw exceptions (i.e, by calling `_CxxThrowException` and not `__abi_WinRTraise*`), msvcrt/ucrt will still use the `cxx_exception_type` RTTI data from `vccorlib`, and not the one passed by the user. It also invokes a callback inside the `exception_info`, which likely performs the necessary RoOriginateError/RoOriginateLanguageException booking, and sets the `IRestrictedErrorInfo` field.

[PATCH 1/1] msvcrt: Use the correct arguments when a WinRT exception is thrown with _CxxThrowException.

[Vibhav Pant]

From: Vibhav Pant

---
 dlls/msvcrt/cpp.c       |  9 +++++++++
 dlls/msvcrt/cppexcept.h | 14 ++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/dlls/msvcrt/cpp.c b/dlls/msvcrt/cpp.c
index c30fd4994a6..9277854ee1c 100644
--- a/dlls/msvcrt/cpp.c
+++ b/dlls/msvcrt/cpp.c
@@ -905,6 +905,15 @@ void WINAPI _CxxThrowException( void *object, const cxx_exception_type *type )

args[0] = CXX_FRAME_MAGIC_VC6;
     args[1] = (ULONG_PTR)object;
+    if (type && type->flags & TYPE_FLAG_IUNKNOWN)
+    {
+        /* This is a COM/WinRT exception, which contains a pointer to com_exception_info just before the object.
+         * We use the exception_type field inside that struct as the actual value for args[2]. */
+         com_exception_info **info = (com_exception_info **)((char *)object - sizeof(void *));
+
+         type = (*info)->exception_type;
+         (*info)->set_exception_info( info );
+    }
     args[2] = (ULONG_PTR)type;
     if (CXX_EXCEPTION_PARAMS == 4) args[3] = cxx_rva_base( type );
     for (;;) RaiseException( CXX_EXCEPTION, EXCEPTION_NONCONTINUABLE, CXX_EXCEPTION_PARAMS, args );
diff --git a/dlls/msvcrt/cppexcept.h b/dlls/msvcrt/cppexcept.h
index 21a7e6a8009..98e26da6f11 100644
--- a/dlls/msvcrt/cppexcept.h
+++ b/dlls/msvcrt/cppexcept.h
@@ -142,6 +142,20 @@ typedef struct
 #define TYPE_FLAG_REFERENCE  8
 #define TYPE_FLAG_IUNKNOWN  16

+typedef struct
+{
+    BSTR message1;
+    BSTR message2;
+    void *unknown1;
+    void *unknown2;
+    HRESULT hr;
+    void *error_info; /* IRestrictedErrorInfo */
+    const cxx_exception_type *exception_type;
+    UINT32 unknown3;
+    /* Sets message1, message2, error_info. */
+    void (*WINAPI set_exception_info)(void *);
+} com_exception_info;
+
 void WINAPI DECLSPEC_NORETURN _CxxThrowException(void*,const cxx_exception_type*);

static inline BOOL is_cxx_exception( EXCEPTION_RECORD *rec )