From fa079fb34b19b52dd92e215f8e58957f206c35e1 Mon Sep 17 00:00:00 2001
From: David Machaj <46852402+dmachaj@users.noreply.github.com>
Date: Tue, 19 Nov 2024 16:25:25 -0800
Subject: [PATCH] Address variable name collisions in generated consume methods
 (#1455)

Why is this change being made?
Someone discovered a subtle compatibility issue with the cast result checking changes and certain projected methods. The variables in the consume_ method, such as the generically-named code variable, can shadow the parameters to the function. This led to a build break where a function took an int16_t named code and that was shadowed by the int32_t named code with the HRESULT in it. Fortunately the compiler had our back and flagged the size truncation as a build break so it was noticed.

Briefly summarize what changed
The variable names in these generated functions are now much uglier (and therefore less likely to collide by coincidence). They have an underscore prefix and then lowercase which should put them into an unofficial namespace that shouldn't collide with anything else. The code variable is now named _winrt_cast_result_code for example. While I was renaming everything I realized that my previous names mismatched the cppwinrt naming convention of snake_case so I fixed them up.
---
 cppwinrt/code_writers.h | 36 ++++++++++++++++++------------------
 1 file changed, 18 insertions(+), 18 deletions(-)

diff --git a/cppwinrt/code_writers.h b/cppwinrt/code_writers.h
index 01f7dea1..9d75d347 100644
--- a/cppwinrt/code_writers.h
+++ b/cppwinrt/code_writers.h
@@ -1137,15 +1137,15 @@ namespace cppwinrt
     {%
         if constexpr (!std::is_same_v<D, %>)
         {
-            auto const [castedResult, code] = impl::try_as_with_reason<%, D const*>(static_cast<D const*>(this));
-            check_hresult(code);
-            auto const abiType = *(abi_t<%>**)&castedResult;
-            abiType->%(%);
+            auto const [_winrt_casted_result, _winrt_cast_result_code] = impl::try_as_with_reason<%, D const*>(static_cast<D const*>(this));
+            check_hresult(_winrt_cast_result_code);
+            auto const _winrt_abi_type = *(abi_t<%>**)&_winrt_casted_result;
+            _winrt_abi_type->%(%);
         }
         else
         {
-            auto const abiType = *(abi_t<%>**)this;
-            abiType->%(%);
+            auto const _winrt_abi_type = *(abi_t<%>**)this;
+            _winrt_abi_type->%(%);
         }%
     }
 )";
@@ -1156,15 +1156,15 @@ namespace cppwinrt
     {%
         if constexpr (!std::is_same_v<D, %>)
         {
-            auto const [castedResult, code] = impl::try_as_with_reason<%, D const*>(static_cast<D const*>(this));
-            check_hresult(code);
-            auto const abiType = *(abi_t<%>**)&castedResult;
-            WINRT_VERIFY_(0, abiType->%(%));
+            auto const [_winrt_casted_result, _winrt_cast_result_code] = impl::try_as_with_reason<%, D const*>(static_cast<D const*>(this));
+            check_hresult(_winrt_cast_result_code);
+            auto const _winrt_abi_type = *(abi_t<%>**)&_winrt_casted_result;
+            WINRT_VERIFY_(0, _winrt_abi_type->%(%));
         }
         else
         {
-            auto const abiType = *(abi_t<%>**)this;
-            WINRT_VERIFY_(0, abiType->%(%));
+            auto const _winrt_abi_type = *(abi_t<%>**)this;
+            WINRT_VERIFY_(0, _winrt_abi_type->%(%));
         }%
     }
 )";
@@ -1176,15 +1176,15 @@ namespace cppwinrt
     {%
         if constexpr (!std::is_same_v<D, %>)
         {
-            auto const [castedResult, code] = impl::try_as_with_reason<%, D const*>(static_cast<D const*>(this));
-            check_hresult(code);
-            auto const abiType = *(abi_t<%>**)&castedResult;
-            check_hresult(abiType->%(%));
+            auto const [_winrt_casted_result, _winrt_cast_result_code] = impl::try_as_with_reason<%, D const*>(static_cast<D const*>(this));
+            check_hresult(_winrt_cast_result_code);
+            auto const _winrt_abi_type = *(abi_t<%>**)&_winrt_casted_result;
+            check_hresult(_winrt_abi_type->%(%));
         }
         else
         {
-            auto const abiType = *(abi_t<%>**)this;
-            check_hresult(abiType->%(%));
+            auto const _winrt_abi_type = *(abi_t<%>**)this;
+            check_hresult(_winrt_abi_type->%(%));
         }%
     }
 )";