[Minor] Fix compilation warnings for clang

[cbalint13]

Fix compilation warnings for clang.

---

The warnings was:

BUILD/tvm/src/target/llvm/llvm_instance.cc:84:81: warning: reference to stack memory associated with parameter 'Obj' returned [-Wreturn-stack-address]
   84 |   friend ArrayRef<SubtargetFeatureKV>& featViewer(MCSubtargetInfo Obj) { return Obj.*Member; }
      |                                                                                 ^~~
BUILD/tvm/src/target/llvm/llvm_instance.cc:833:49: 
 warning: cast from 'const llvm::MCSubtargetInfo *' to 'llvm::MCSubtargetInfo *' drops const qualifier [-Wcast-qual]
  833 |       llvm::featViewer(*(llvm::MCSubtargetInfo*)MCInfo);
      |                                                 ^
BUILD/tvm/src/target/llvm/llvm_instance.cc:84:81: 
 warning: reference to stack memory associated with parameter 'Obj' returned [-Wreturn-stack-address]
   84 |   friend ArrayRef<SubtargetFeatureKV>& featViewer(MCSubtargetInfo Obj) { return Obj.*Member; }
      |                                                                                 ^~~
BUILD/tvm/src/target/llvm/llvm_instance.cc:833:13: note: in instantiation of member function 'llvm::featViewer' requested here
  833 |       llvm::featViewer(*(llvm::MCSubtargetInfo*)MCInfo);
      |           

$ rpm -q clang
clang-17.0.2-1.fc40.x86_64

No warnings was for: gcc (13.2) or vscode (2019) sides.

Cc: @junrushao

[quic-sanirudh]

LGTM, Thanks.

[junrushao]

Hey @cbalint13 thanks a lot for the swift fix!! Yeah this issue was reported by clang++ on macOS, and I can confirm it’s gone with this change. Thanks again 🙏

[cbalint13]

Hey @cbalint13 thanks a lot for the swift fix!! Yeah this issue was reported by clang++ on macOS, and I can confirm it’s gone with this change. Thanks again 🙏

With pleasure, anytime.

---

Just some extra info:

I also checked using gcc's "hardening" stack-protector flags, being a default thing for fedora/redhat releng, and it is fine.

Short, the very flag: -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong

The full flags, added by rhel/fedora at packaging creation time:

$ rpm --eval %{optflags}
-O2 -flto=auto -ffat-lto-objects -fexceptions -g -grecord-gcc-switches -pipe -Wall 
-Wno-complain-wrong-lang -Werror=format-security -Werror=implicit-function-declaration 
-Werror=implicit-int -Wp,-U_FORTIFY_SOURCE,-D_FORTIFY_SOURCE=3 -Wp,-D_GLIBCXX_ASSERTIONS 
-specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong 
-specs=/usr/lib/rpm/redhat/redhat-annobin-cc1  -m64   -mtune=generic 
-fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection -fno-omit-frame-pointer 
-mno-omit-leaf-frame-pointer

[junrushao]

Thanks for testing with the extra stack protector 🙏❤️ Let's get it merged soon!