[libunwind] Bump to CXX_STANDARD 17

[MaskRay]

libunwind uses C-style and low-level C++, so the language standard
doesn't matter that much, but bumping to C++17 aligns with the rest of
LLVM and enables some features that would cause pedantic warnings in
C++11 (e.g. -Wc++17-attribute-extensions for [[fallthrough]]/
[[nodiscard]]/[[maybe_unused]]). (Contributors might use these features
unaware of the pedantic warnings).

Suggested-by: Christopher Di Bella cjdb@google.com

[llvmbot]

@llvm/pr-subscribers-libunwind

Author: Fangrui Song (MaskRay)

Changes

libunwind uses C-style and low-level C++, so the language standard
doesn't matter that much, but bumping to C++17 aligns with the rest of
LLVM and enables some features that would cause pedantic warnings in
C++11 (e.g. -Wc++17-attribute-extensions for [[fallthrough]]/
[[nodiscard]]/[[maybe_unused]]). (Contributors might use these features
unaware of the pedantic warnings).

Suggested-by: Christopher Di Bella <cjdb@google.com>

---

Full diff: https://github.com/llvm/llvm-project/pull/75986.diff

1 Files Affected:

• (modified) libunwind/src/CMakeLists.txt (+2-2)

diff --git a/libunwind/src/CMakeLists.txt b/libunwind/src/CMakeLists.txt
index 570824260465d6..9c6f5d908b0945 100644
--- a/libunwind/src/CMakeLists.txt
+++ b/libunwind/src/CMakeLists.txt
@@ -154,7 +154,7 @@ target_link_libraries(unwind_shared_objects PUBLIC "${LIBUNWIND_ADDITIONAL_LIBRA
 set_target_properties(unwind_shared_objects
   PROPERTIES
     CXX_EXTENSIONS OFF
-    CXX_STANDARD 11
+    CXX_STANDARD 17
     CXX_STANDARD_REQUIRED ON
     COMPILE_FLAGS "${LIBUNWIND_COMPILE_FLAGS}"
 )
@@ -194,7 +194,7 @@ target_link_libraries(unwind_static_objects PUBLIC "${LIBUNWIND_ADDITIONAL_LIBRA
 set_target_properties(unwind_static_objects
   PROPERTIES
     CXX_EXTENSIONS OFF
-    CXX_STANDARD 11
+    CXX_STANDARD 17
     CXX_STANDARD_REQUIRED ON
     COMPILE_FLAGS "${LIBUNWIND_COMPILE_FLAGS}"
 )

[compnerd]

Sure, aligning with the rest of LLVM makes sense

[cjdb]

Thanks for making this change!

CC @ajordanr-google