Edit release notes

Author: YutongZhuu

clang/docs/ReleaseNotes.rst

@@ -352,6 +352,9 @@ Improvements to Clang's diagnostics
 - Now correctly diagnose a tentative definition of an array with static
   storage duration in pedantic mode in C. (#GH50661)
 
+- Split diagnosis of implicit integer comparison on negation to a new diagnostic group ``-Wimplicit-int-comparison-on-negation``, 
+  so user can turn it off independently.
+
 Improvements to Clang's time-trace
 ----------------------------------
 

clang/test/Sema/implicit-int-conversion-on-int.c

@@ -9,4 +9,4 @@ unsigned char test_no_diag(unsigned char x) {
 unsigned char test_diag(unsigned char x) {
     return -x; // expected-warning {{implicit conversion loses integer precision: 'int' to 'unsigned char' on negation}}
 }
-#endif
+#endif