https://github.com/OSGeo/gdal/commit/9f1da7a2546e4df2cd63b99c7fefc7f2e607260a

From 32493387de801ff143acad7572591d88ead4326a Mon Sep 17 00:00:00 2001
From: Nicklas Larsson <n_larsson@yahoo.com>
Date: Mon, 8 Jun 2026 09:36:13 +0200
Subject: [PATCH] GTiff: Avoid value-initialization of vector of forward
 declared class

Addresses "invalid application of 'sizeof' to an incomplete type 'GTiffJPEGOverviewDS'" compiler
error on macOS 12 and earlier (with AppleClang 13 and earlier).
---
 frmts/gtiff/gtiffdataset.cpp | 5 ++++-
 frmts/gtiff/gtiffdataset.h   | 4 ++--
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/frmts/gtiff/gtiffdataset.cpp b/frmts/gtiff/gtiffdataset.cpp
index fc2fc114b868..c25d26bd145b 100644
--- frmts/gtiff/gtiffdataset.cpp
+++ frmts/gtiff/gtiffdataset.cpp
@@ -70,7 +70,10 @@ const GTIFFTag *GTiffDataset::GetTIFFTags()
 /************************************************************************/
 
 GTiffDataset::GTiffDataset()
-    : m_bStreamingIn(false), m_bStreamingOut(false), m_bScanDeferred(true),
+    : m_apoJPEGOverviewDS(std::vector<std::unique_ptr<GTiffJPEGOverviewDS>>{}),
+      m_apoJPEGOverviewDSOld(
+          std::vector<std::unique_ptr<GTiffJPEGOverviewDS>>{}),
+      m_bStreamingIn(false), m_bStreamingOut(false), m_bScanDeferred(true),
       m_bSingleIFDOpened(false), m_bLoadedBlockDirty(false),
       m_bWriteError(false), m_bLookedForProjection(false),
       m_bLookedForMDAreaOrPoint(false), m_bGeoTransformValid(false),
diff --git a/frmts/gtiff/gtiffdataset.h b/frmts/gtiff/gtiffdataset.h
index 58dc03c1a501..817cbb003797 100644
--- frmts/gtiff/gtiffdataset.h
+++ frmts/gtiff/gtiffdataset.h
@@ -133,8 +133,8 @@ class GTiffDataset final : public GDALPamDataset
     GTiffDataset *m_poBaseDS = nullptr;
     // Used with MASK_OVERVIEW_DATASET open option
     std::unique_ptr<GDALDataset> m_poMaskExtOvrDS{};
-    std::vector<std::unique_ptr<GTiffJPEGOverviewDS>> m_apoJPEGOverviewDS{};
-    std::vector<std::unique_ptr<GTiffJPEGOverviewDS>> m_apoJPEGOverviewDSOld{};
+    std::vector<std::unique_ptr<GTiffJPEGOverviewDS>> m_apoJPEGOverviewDS;
+    std::vector<std::unique_ptr<GTiffJPEGOverviewDS>> m_apoJPEGOverviewDSOld;
     std::vector<gdal::GCP> m_aoGCPs{};
     std::unique_ptr<GDALColorTable> m_poColorTable{};
     char **m_papszMetadataFiles = nullptr;