[lldb] [Windows] Silence format string warnings

[mstorsjo]

This fixes the following build warnings in a mingw environment:

../../lldb/source/Host/windows/MainLoopWindows.cpp:226:50: warning: format specifies type 'int' but the argument has type 'IOObject::WaitableHandle' (aka 'void *') [-Wformat]
  226 |         "File descriptor %d already monitored.", waitable_handle);
      |                          ~~                      ^~~~~~~~~~~~~~~
../../lldb/source/Host/windows/MainLoopWindows.cpp:239:49: warning: format specifies type 'int' but the argument has type 'DWORD' (aka 'unsigned long') [-Wformat]
  238 |       error = Status::FromErrorStringWithFormat("Unsupported file type %d",
      |                                                                        ~~
      |                                                                        %lu
  239 |                                                 file_type);
      |                                                 ^~~~~~~~~
2 warnings generated.

[llvmbot]

@llvm/pr-subscribers-lldb

Author: Martin Storsjö (mstorsjo)

Changes

This fixes the following build warnings in a mingw environment:

../../lldb/source/Host/windows/MainLoopWindows.cpp:226:50: warning: format specifies type 'int' but the argument has type 'IOObject::WaitableHandle' (aka 'void *') [-Wformat]
  226 |         "File descriptor %d already monitored.", waitable_handle);
      |                          ~~                      ^~~~~~~~~~~~~~~
../../lldb/source/Host/windows/MainLoopWindows.cpp:239:49: warning: format specifies type 'int' but the argument has type 'DWORD' (aka 'unsigned long') [-Wformat]
  238 |       error = Status::FromErrorStringWithFormat("Unsupported file type %d",
      |                                                                        ~~
      |                                                                        %lu
  239 |                                                 file_type);
      |                                                 ^~~~~~~~~
2 warnings generated.

---

Full diff: https://github.com/llvm/llvm-project/pull/150886.diff

1 Files Affected:

• (modified) lldb/source/Host/windows/MainLoopWindows.cpp (+2-2)

diff --git a/lldb/source/Host/windows/MainLoopWindows.cpp b/lldb/source/Host/windows/MainLoopWindows.cpp
index c1a018238432d..f7f65a82f726f 100644
--- a/lldb/source/Host/windows/MainLoopWindows.cpp
+++ b/lldb/source/Host/windows/MainLoopWindows.cpp
@@ -223,7 +223,7 @@ MainLoopWindows::RegisterReadObject(const IOObjectSP &object_sp,
 
   if (m_read_fds.find(waitable_handle) != m_read_fds.end()) {
     error = Status::FromErrorStringWithFormat(
-        "File descriptor %d already monitored.", waitable_handle);
+        "File descriptor %p already monitored.", waitable_handle);
     return nullptr;
   }
 
@@ -236,7 +236,7 @@ MainLoopWindows::RegisterReadObject(const IOObjectSP &object_sp,
     DWORD file_type = GetFileType(waitable_handle);
     if (file_type != FILE_TYPE_PIPE) {
       error = Status::FromErrorStringWithFormat("Unsupported file type %d",
-                                                file_type);
+                                                static_cast<int>(file_type));
       return nullptr;
     }
 

[DavidSpickett]

Should you use %lu instead of casting? https://learn.microsoft.com/en-gb/windows/win32/winprog/windows-data-types?redirectedfrom=MSDN:

A 32-bit unsigned integer. The range is 0 through 4294967295 decimal.
This type is declared in IntSafe.h as follows:
typedef unsigned long DWORD;

I assume since they didn't note it, it's the same size on x86 and x86_64.

[DavidSpickett]

Oh but is there a Mingw detail here that means the cast is better?

[mstorsjo]

Oh but is there a Mingw detail here that means the cast is better?

No, mingw should conform quite closely regarding such details. I just didn't feel like assuming such details about the type of DWORD, but you're right, and it should be fine to do that instead. Will update.

[mstorsjo]

Tested that this still silences the warnings, on both 32 and 64 bit.

[labath]

Looks good, though personally, I'd use FromErrorStringWithFormatv and let it deduce the format.

[mstorsjo]

/cherry-pick 98ec927

[llvmbot]

/pull-request #150919