[Lldb-commits] [lldb] [lldb] Fix `from_size` initialization in `DoIntegralPromotion` (PR #191421)

[Ilia Kuklin via lldb-commits]

https://github.com/kuilpd created https://github.com/llvm/llvm-project/pull/191421

The check `(*from_size == *int_byte_size)` can only pass on systems where `short` and `int` types are the same width, which is why the bug was never triggered by tests.

>From bff9f6d51c8062feeb02c8a4b6df5626889f5eff Mon Sep 17 00:00:00 2001
From: Ilia Kuklin <ikuklin at accesssoftek.com>
Date: Fri, 10 Apr 2026 18:53:54 +0500
Subject: [PATCH] [lldb] Fix `from_size` initialization in
 TypeSystemClang::DoIntegralPromotion

---
 lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp b/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
index 86d39b51e9b4c..8689b5b353368 100644
--- a/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
+++ b/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
@@ -7315,7 +7315,9 @@ TypeSystemClang::DoIntegralPromotion(CompilerType from,
 
   lldb::BasicType builtin_type =
       from.GetCanonicalType().GetBasicTypeEnumeration();
-  uint64_t from_size = 0;
+  llvm::Expected<uint64_t> from_size = from.GetByteSize(exe_scope);
+  if (!from_size)
+    return from_size.takeError();
   if (builtin_type == lldb::eBasicTypeWChar ||
       builtin_type == lldb::eBasicTypeSignedWChar ||
       builtin_type == lldb::eBasicTypeUnsignedWChar ||
@@ -7323,9 +7325,6 @@ TypeSystemClang::DoIntegralPromotion(CompilerType from,
       builtin_type == lldb::eBasicTypeChar32) {
     // Find the type that can hold the entire range of values for our type.
     bool is_signed = from.IsSigned();
-    llvm::Expected<uint64_t> from_size = from.GetByteSize(exe_scope);
-    if (!from_size)
-      return from_size.takeError();
     CompilerType promote_types[] = {
         GetBasicTypeFromAST(lldb::eBasicTypeInt),
         GetBasicTypeFromAST(lldb::eBasicTypeUnsignedInt),
@@ -7358,7 +7357,7 @@ TypeSystemClang::DoIntegralPromotion(CompilerType from,
   }
   // Unsigned integer types are promoted to "unsigned int" if "int" cannot hold
   // their entire value range.
-  return (from_size == *int_byte_size)
+  return (*from_size == *int_byte_size)
              ? GetBasicTypeFromAST(lldb::eBasicTypeUnsignedInt)
              : int_type;
 }