Remove most C++ from pgduckdb.cpp

include/pgduckdb/pgduckdb.h

@@ -7,8 +7,21 @@ typedef enum {
 	MOTHERDUCK_AUTO,
 } MotherDuckEnabled;
 
-// pgduckdb.c
+// pgduckdb.cpp
 extern "C" void _PG_init(void);
 
-// pgduckdb_hooks.c
-void DuckdbInitHooks(void);
+void DuckdbInitGUC();
+
+// pgduckdb_hooks.cpp
+void DuckdbInitHooks();
+
+// pgduckdb_node.cpp
+void DuckdbInitNode();
+
+// pgduckdb_background_worker.cpp
+void DuckdbInitBackgroundWorker();
+
+namespace pgduckdb {
+// pgduckdb_xact.cpp
+void RegisterDuckdbXactCallback();
+} // namespace pgduckdb

include/pgduckdb/pgduckdb_background_worker.hpp

@@ -1,7 +1,5 @@
 #pragma once
 
-void DuckdbInitBackgroundWorker(void);
-
 namespace pgduckdb {
 
 void SyncMotherDuckCatalogsWithPg(bool drop_with_cascade);

include/pgduckdb/pgduckdb_node.hpp

@@ -6,4 +6,3 @@ extern "C" {
 }
 
 extern CustomScanMethods duckdb_scan_scan_methods;
-extern "C" void DuckdbInitNode(void);

include/pgduckdb/pgduckdb_xact.hpp

@@ -6,7 +6,6 @@ void PreventInTransactionBlock(const char *statement_type);
 } // namespace pg
 
 void ClaimCurrentCommandId();
-void RegisterDuckdbXactCallback();
 void AutocommitSingleStatementQueries();
 void MarkStatementNotTopLevel();
 } // namespace pgduckdb

src/pgduckdb.cpp

@@ -1,18 +1,13 @@
-#include "duckdb.hpp"
+#include "pgduckdb/pgduckdb.h"
+
+#include <type_traits>
 
 extern "C" {
 #include "postgres.h"
 #include "miscadmin.h"
 #include "utils/guc.h"
 }
 
-#include "pgduckdb/pgduckdb.h"
-#include "pgduckdb/pgduckdb_node.hpp"
-#include "pgduckdb/pgduckdb_background_worker.hpp"
-#include "pgduckdb/pgduckdb_xact.hpp"
-
-static void DuckdbInitGUC(void);
-
 bool duckdb_force_execution = false;
 int duckdb_max_threads_per_postgres_scan = 1;
 int duckdb_motherduck_enabled = MotherDuckEnabled::MOTHERDUCK_AUTO;
@@ -99,6 +94,7 @@ DefineCustomVariable(const char *name, const char *short_desc, T *var, T min, T
 	} else {
 		static_assert("Unsupported type");
 	}
+
 	func(name, gettext_noop(short_desc), NULL, var, *var, min, max, context, flags, check_hook, assign_hook, show_hook);
 }
 
@@ -122,8 +118,8 @@ static const struct config_enum_entry motherduck_enabled_options[] = {
 };
 /* clang-format on */
 
-static void
-DuckdbInitGUC(void) {
+void
+DuckdbInitGUC() {
 	DefineCustomVariable("duckdb.force_execution", "Force queries to use DuckDB execution", &duckdb_force_execution);
 
 	DefineCustomVariable("duckdb.enable_external_access", "Allow the DuckDB to access external state.",

src/pgduckdb_background_worker.cpp

@@ -125,7 +125,7 @@ force_motherduck_sync(PG_FUNCTION_ARGS) {
 }
 
 void
-DuckdbInitBackgroundWorker(void) {
+DuckdbInitBackgroundWorker() {
 	if (!pgduckdb::IsMotherDuckEnabledAnywhere()) {
 		return;
 	}

src/pgduckdb_hooks.cpp

@@ -256,11 +256,7 @@ IsDuckdbPlan(PlannedStmt *stmt) {
 	}
 
 	CustomScan *custom_scan = castNode(CustomScan, plan);
-	if (custom_scan->methods != &duckdb_scan_scan_methods) {
-		return false;
-	}
-
-	return true;
+	return custom_scan->methods == &duckdb_scan_scan_methods;
 }
 
 /*

src/pgduckdb_node.cpp

@@ -265,7 +265,7 @@ Duckdb_ExplainCustomScan(CustomScanState *node, List * /*ancestors*/, ExplainSta
 	InvokeCPPFunc(Duckdb_ExplainCustomScan_Cpp, node, es);
 }
 
-extern "C" void
+void
 DuckdbInitNode() {
 	/* setup scan methods */
 	memset(&duckdb_scan_scan_methods, 0, sizeof(duckdb_scan_scan_methods));