[clang] Enable the -Wdangling-assignment-gsl diagnostic by default. (#100708)

Author: hokein

clang/docs/ReleaseNotes.rst

@@ -133,6 +133,8 @@ Improvements to Clang's diagnostics
 
 - Clang now diagnoses undefined behavior in constant expressions more consistently. This includes invalid shifts, and signed overflow in arithmetic.
 
+- -Wdangling-assignment-gsl is enabled by default.
+
 Improvements to Clang's time-trace
 ----------------------------------
 

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -10131,7 +10131,7 @@ def warn_dangling_lifetime_pointer : Warning<
   InGroup<DanglingGsl>;
 def warn_dangling_lifetime_pointer_assignment : Warning<"object backing the "
   "pointer %0 will be destroyed at the end of the full-expression">,
-  InGroup<DanglingAssignmentGsl>, DefaultIgnore;
+  InGroup<DanglingAssignmentGsl>;
 def warn_new_dangling_initializer_list : Warning<
   "array backing "
   "%select{initializer list subobject of the allocated object|"