[clang] [llvm] [NFC] Address bit-field storage sizes to ensure ideal packing (PR #139825)

[via cfe-commits]

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@@ -74,20 +75,23 @@ enum DiagnosticClass {
 struct StaticDiagInfoRec {
   uint16_t DiagID;
   LLVM_PREFERRED_TYPE(diag::Severity)
-  uint8_t DefaultSeverity : 3;
+  uint16_t DefaultSeverity : 3;
   LLVM_PREFERRED_TYPE(DiagnosticClass)
-  uint8_t Class : 3;
+  uint16_t Class : 3;
   LLVM_PREFERRED_TYPE(DiagnosticIDs::SFINAEResponse)
-  uint8_t SFINAE : 2;
-  uint8_t Category : 6;
+  uint16_t SFINAE : 2;
+  LLVM_PREFERRED_TYPE(diag::DiagCategory)
+  uint16_t Category : 6;
   LLVM_PREFERRED_TYPE(bool)
-  uint8_t WarnNoWerror : 1;
+  uint16_t WarnNoWerror : 1;
   LLVM_PREFERRED_TYPE(bool)
-  uint8_t WarnShowInSystemHeader : 1;
+  uint16_t WarnShowInSystemHeader : 1;
   LLVM_PREFERRED_TYPE(bool)
-  uint8_t WarnShowInSystemMacro : 1;
+  uint16_t WarnShowInSystemMacro : 1;
 
+  LLVM_PREFERRED_TYPE(diag::Group)
   uint16_t OptionGroupIndex : 15;
+
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cor3ntin wrote:

Would the size be reduced if DescriptionLen was a bit shorter?

https://github.com/llvm/llvm-project/pull/139825