fix: repair shared package linkage and export scan builder symbols

1. Update the shared installation interface to depend on the
   static nanoarrow target, since vendored libraries are built
   only as static artifacts(see prepare_fetchcontent).

2. Switch the example build to use shared libraries to surface
   linkage issues. This revealed that `TableScanBuilder` symbols
   are not exported. Explicitly export the `TableScanBuilder`
   template instantiations so that shared-library consumers can
   successfully link against `Build()`.

Author: zhjwpku

example/CMakeLists.txt

@@ -26,5 +26,5 @@ find_package(iceberg CONFIG REQUIRED)
 
 add_executable(demo_example demo_example.cc)
 
-target_link_libraries(demo_example PRIVATE iceberg::iceberg_bundle_static
-                                           iceberg::iceberg_rest_static)
+target_link_libraries(demo_example PRIVATE iceberg::iceberg_bundle_shared
+                                           iceberg::iceberg_rest_shared)

src/iceberg/CMakeLists.txt

@@ -149,7 +149,7 @@ list(APPEND
      "$<IF:$<BOOL:${CROARING_VENDORED}>,iceberg::roaring,roaring::roaring>")
 list(APPEND
      ICEBERG_SHARED_INSTALL_INTERFACE_LIBS
-     "$<IF:$<BOOL:${NANOARROW_VENDORED}>,iceberg::nanoarrow_shared,$<IF:$<TARGET_EXISTS:nanoarrow::nanoarrow_shared>,nanoarrow::nanoarrow_shared,nanoarrow::nanoarrow_static>>"
+     "$<IF:$<BOOL:${NANOARROW_VENDORED}>,iceberg::nanoarrow_static,$<IF:$<TARGET_EXISTS:nanoarrow::nanoarrow_shared>,nanoarrow::nanoarrow_shared,nanoarrow::nanoarrow_static>>"
      "$<IF:$<BOOL:${NLOHMANN_JSON_VENDORED}>,iceberg::nlohmann_json,$<IF:$<TARGET_EXISTS:nlohmann_json::nlohmann_json>,nlohmann_json::nlohmann_json,nlohmann_json::nlohmann_json>>"
      "$<IF:$<BOOL:${CROARING_VENDORED}>,iceberg::roaring,roaring::roaring>")
 

src/iceberg/iceberg_export.h

@@ -53,5 +53,5 @@
 
 #  define ICEBERG_TEMPLATE_EXPORT
 #  define ICEBERG_TEMPLATE_CLASS_EXPORT ICEBERG_EXPORT
-#  define ICEBERG_EXTERN_TEMPLATE_CLASS_EXPORT ICEBERG_TEMPLATE_EXPORT
+#  define ICEBERG_EXTERN_TEMPLATE_CLASS_EXPORT ICEBERG_TEMPLATE_CLASS_EXPORT
 #endif

src/iceberg/table_scan.cc

@@ -535,9 +535,9 @@ Result<std::unique_ptr<ScanType>> TableScanBuilder<ScanType>::Build() {
 }
 
 // Explicit template instantiations
-template class TableScanBuilder<DataTableScan>;
-template class TableScanBuilder<IncrementalAppendScan>;
-template class TableScanBuilder<IncrementalChangelogScan>;
+template class ICEBERG_TEMPLATE_EXPORT TableScanBuilder<DataTableScan>;
+template class ICEBERG_TEMPLATE_EXPORT TableScanBuilder<IncrementalAppendScan>;
+template class ICEBERG_TEMPLATE_EXPORT TableScanBuilder<IncrementalChangelogScan>;
 
 TableScan::TableScan(std::shared_ptr<TableMetadata> metadata,
                      std::shared_ptr<Schema> schema, std::shared_ptr<FileIO> file_io,

src/iceberg/table_scan.h

@@ -28,6 +28,7 @@
 #include <vector>
 
 #include "iceberg/arrow_c_data.h"
+#include "iceberg/iceberg_export.h"
 #include "iceberg/result.h"
 #include "iceberg/table_metadata.h"
 #include "iceberg/type_fwd.h"
@@ -252,7 +253,7 @@ concept IsIncrementalScan = std::is_base_of_v<IncrementalScan<FileScanTask>, T>
 
 /// \brief Builder class for creating TableScan instances.
 template <typename ScanType = DataTableScan>
-class ICEBERG_EXPORT TableScanBuilder : public ErrorCollector {
+class ICEBERG_TEMPLATE_CLASS_EXPORT TableScanBuilder : public ErrorCollector {
  public:
   /// \brief Constructs a TableScanBuilder for the given table.
   /// \param metadata Current table metadata.
@@ -524,4 +525,11 @@ class ICEBERG_EXPORT IncrementalChangelogScan
   using IncrementalScan::IncrementalScan;
 };
 
+extern template class ICEBERG_EXTERN_TEMPLATE_CLASS_EXPORT
+    TableScanBuilder<DataTableScan>;
+extern template class ICEBERG_EXTERN_TEMPLATE_CLASS_EXPORT
+    TableScanBuilder<IncrementalAppendScan>;
+extern template class ICEBERG_EXTERN_TEMPLATE_CLASS_EXPORT
+    TableScanBuilder<IncrementalChangelogScan>;
+
 }  // namespace iceberg