[Lldb-commits] [clang] [lldb] [lldb] Analyze enum promotion type during parsing (PR #115005)

[Michael Buch via lldb-commits]

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@@ -2367,11 +2369,38 @@ size_t DWARFASTParserClang::ParseChildEnumerators(
     }
 
     if (name && name[0] && got_value) {
-      m_ast.AddEnumerationValueToEnumerationType(
+      auto ECD = m_ast.AddEnumerationValueToEnumerationType(
           clang_type, decl, name, enum_value, enumerator_byte_size * 8);
       ++enumerators_added;
+
+      llvm::APSInt InitVal = ECD->getInitVal();
+      // Keep track of the size of positive and negative values.
+      if (InitVal.isUnsigned() || InitVal.isNonNegative()) {
+        // If the enumerator is zero that should still be counted as a positive
+        // bit since we need a bit to store the value zero.
+        unsigned ActiveBits = InitVal.getActiveBits();
+        NumPositiveBits = std::max({NumPositiveBits, ActiveBits, 1u});
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Michael137 wrote:

Oh I didn't realize you're doing this over a loop. And you're mimicking the behaviour of SemaDecl. Hmmm again this feels like something we could share with Clang. Something like `bool computeEnumBits(unsigned &NumNegativeBits, unsigned &NumPositiveBits` (where the return value implies `MembersRepresentableByInt`). Then just call it from `TypeSystemClang::CompleteTagDeclarationDefinition`. What do you think?

I feel like that would reduce the diff in this patch quite nicely

https://github.com/llvm/llvm-project/pull/115005