Prepare C code for compiling on Windows

For all exported functions the macro PGDLLEXPORT needs to be pre-
pended. Additionally, on Windows `open` is a macro that needed to
be renamed. A few other small changes are done to make Visual
Studio's compiler happy / get rid of warnings (e.g. adding return
statements after elog).

src/agg_bookend.c

@@ -15,6 +15,15 @@
  *	 SELECT first(metric, time), last(metric, time) FROM metric GROUP BY hostname.
  */
 
+PGDLLEXPORT Datum first_sfunc(PG_FUNCTION_ARGS);
+PGDLLEXPORT Datum first_combinefunc(PG_FUNCTION_ARGS);
+PGDLLEXPORT Datum last_sfunc(PG_FUNCTION_ARGS);
+PGDLLEXPORT Datum last_combinefunc(PG_FUNCTION_ARGS);
+PGDLLEXPORT Datum bookend_finalfunc(PG_FUNCTION_ARGS);
+PGDLLEXPORT Datum bookend_serializefunc(PG_FUNCTION_ARGS);
+PGDLLEXPORT Datum bookend_deserializefunc(PG_FUNCTION_ARGS);
+
+
 PG_FUNCTION_INFO_V1(first_sfunc);
 PG_FUNCTION_INFO_V1(first_combinefunc);
 PG_FUNCTION_INFO_V1(last_sfunc);
@@ -369,7 +378,6 @@ bookend_combinefunc(MemoryContext aggcontext, InternalCmpAggStore *state1, Inter
 	PG_RETURN_POINTER(state1);
 }
 
-
 /* first(internal internal_state, anyelement value, "any" comparison_element) */
 Datum
 first_sfunc(PG_FUNCTION_ARGS)

src/cache.h

@@ -8,7 +8,7 @@
 typedef struct CacheQuery
 {
 	void	   *result;
-	void	   *data[0];
+	void	   *data;
 } CacheQuery;
 
 typedef struct CacheStats

src/cache_invalidate.c

@@ -60,6 +60,7 @@ inval_cache_callback(Datum arg, Oid relid)
 		hypertable_cache_invalidate_callback();
 }
 
+PGDLLEXPORT Datum invalidate_relcache_trigger(PG_FUNCTION_ARGS);
 PG_FUNCTION_INFO_V1(invalidate_relcache_trigger);
 
 /*
@@ -101,6 +102,7 @@ invalidate_relcache_trigger(PG_FUNCTION_ARGS)
 		return PointerGetDatum(trigdata->tg_trigtuple);
 }
 
+PGDLLEXPORT Datum invalidate_relcache(PG_FUNCTION_ARGS);
 PG_FUNCTION_INFO_V1(invalidate_relcache);
 
 /*

src/chunk.h

@@ -36,7 +36,7 @@ typedef struct Chunk
 	Hypercube  *cube;
 	int16		capacity;
 	int16		num_constraints;
-	ChunkConstraint constraints[0];
+	ChunkConstraint constraints[FLEXIBLE_ARRAY_MEMBER];
 } Chunk;
 
 #define CHUNK_SIZE(num_constraints)								\

src/chunk_constraint.h

@@ -16,7 +16,7 @@ typedef struct ChunkConstraint
 typedef struct ChunkConstraintVec
 {
 	int16		num_constraints;
-	ChunkConstraint constraints[0];
+	ChunkConstraint constraints[FLEXIBLE_ARRAY_MEMBER];
 }	ChunkConstraintVec;
 
 typedef struct Chunk Chunk;

src/compat.c

@@ -3,6 +3,7 @@
 
 /* Old functions that are no longer used but are needed for compatibiliy when
  * updating the extension. */
+PGDLLEXPORT Datum insert_main_table_trigger(PG_FUNCTION_ARGS);
 PG_FUNCTION_INFO_V1(insert_main_table_trigger);
 
 Datum
@@ -12,6 +13,7 @@ insert_main_table_trigger(PG_FUNCTION_ARGS)
 	PG_RETURN_NULL();
 }
 
+PGDLLEXPORT Datum insert_main_table_trigger_after(PG_FUNCTION_ARGS);
 PG_FUNCTION_INFO_V1(insert_main_table_trigger_after);
 
 Datum
@@ -21,6 +23,7 @@ insert_main_table_trigger_after(PG_FUNCTION_ARGS)
 	PG_RETURN_NULL();
 }
 
+PGDLLEXPORT Datum ddl_is_change_owner(PG_FUNCTION_ARGS);
 PG_FUNCTION_INFO_V1(ddl_is_change_owner);
 
 Datum
@@ -30,6 +33,7 @@ ddl_is_change_owner(PG_FUNCTION_ARGS)
 	PG_RETURN_NULL();
 }
 
+PGDLLEXPORT Datum ddl_change_owner_to(PG_FUNCTION_ARGS);
 PG_FUNCTION_INFO_V1(ddl_change_owner_to);
 
 Datum

src/dimension.c

@@ -149,6 +149,7 @@ calculate_open_range_default(Dimension *dim, int64 value)
 	return dimension_slice_create(dim->fd.id, range_start, range_end);
 }
 
+PGDLLEXPORT Datum dimension_calculate_open_range_default(PG_FUNCTION_ARGS);
 PG_FUNCTION_INFO_V1(dimension_calculate_open_range_default);
 
 /*
@@ -194,6 +195,7 @@ calculate_closed_range_default(Dimension *dim, int64 value)
 	return dimension_slice_create(dim->fd.id, range_start, range_end);
 }
 
+PGDLLEXPORT Datum dimension_calculate_closed_range_default(PG_FUNCTION_ARGS);
 PG_FUNCTION_INFO_V1(dimension_calculate_closed_range_default);
 
 /*

src/dimension.h

@@ -42,7 +42,7 @@ typedef struct Hyperspace
 	uint16		capacity;
 	uint16		num_dimensions;
 	/* Open dimensions should be stored before closed dimensions */
-	Dimension	dimensions[0];
+	Dimension	dimensions[FLEXIBLE_ARRAY_MEMBER];
 } Hyperspace;
 
 #define HYPERSPACE_SIZE(num_dimensions)							\
@@ -56,7 +56,7 @@ typedef struct Point
 	int16		cardinality;
 	uint8		num_coords;
 	/* Open dimension coordinates are stored before the closed coordinates */
-	int64		coordinates[0];
+	int64		coordinates[FLEXIBLE_ARRAY_MEMBER];
 } Point;
 
 #define POINT_SIZE(cardinality)							\

src/dimension_vector.h

@@ -14,7 +14,7 @@ typedef struct DimensionVec
 	int32		capacity;		/* The capacity of the slices array */
 	int32		num_slices;		/* The current number of slices in slices
 								 * array */
-	DimensionSlice *slices[0];
+	DimensionSlice *slices[FLEXIBLE_ARRAY_MEMBER];
 } DimensionVec;
 
 #define DIMENSION_VEC_SIZE(num_slices)								\

src/event_trigger.c

@@ -5,6 +5,8 @@
 
 #include "event_trigger.h"
 
+#define DDL_INFO_NATTS 9
+
 /* Function manager info for the event "pg_event_trigger_ddl_commands", which is
  * used to retrieve information on executed DDL commands in an event
  * trigger. The function manager info is initialized on extension load. */
@@ -42,8 +44,8 @@ event_trigger_ddl_commands(void)
 	{
 		HeapTuple	tuple = ExecFetchSlotTuple(slot);
 		CollectedCommand *cmd;
-		Datum		values[rsinfo.setDesc->natts];
-		bool		nulls[rsinfo.setDesc->natts];
+		Datum		values[DDL_INFO_NATTS];
+		bool		nulls[DDL_INFO_NATTS];
 
 		heap_deform_tuple(tuple, rsinfo.setDesc, values, nulls);
 

src/extension.c

@@ -167,6 +167,7 @@ extension_invalidate(Oid relid)
 			return false;
 		default:
 			elog(ERROR, "unknown state: %d", extstate);
+			return false;
 	}
 }
 
@@ -201,5 +202,6 @@ extension_is_loaded(void)
 			return false;
 		default:
 			elog(ERROR, "unknown state: %d", extstate);
+			return false;
 	}
 }

src/histogram.c

@@ -21,6 +21,12 @@
  * nbucket+2 buckets accounting for buckets outside the range.
  */
 
+PGDLLEXPORT Datum hist_sfunc(PG_FUNCTION_ARGS);
+PGDLLEXPORT Datum hist_combinefunc(PG_FUNCTION_ARGS);
+PGDLLEXPORT Datum hist_serializefunc(PG_FUNCTION_ARGS);
+PGDLLEXPORT Datum hist_deserializefunc(PG_FUNCTION_ARGS);
+PGDLLEXPORT Datum hist_finalfunc(PG_FUNCTION_ARGS);
+
 PG_FUNCTION_INFO_V1(hist_sfunc);
 PG_FUNCTION_INFO_V1(hist_combinefunc);
 PG_FUNCTION_INFO_V1(hist_serializefunc);

src/hypercube.h

@@ -15,7 +15,7 @@ typedef struct Hypercube
 	int16		num_slices;		/* actual number of slices (should equal
 								 * capacity after create) */
 	/* Slices are stored in dimension order */
-	DimensionSlice *slices[0];
+	DimensionSlice *slices[FLEXIBLE_ARRAY_MEMBER];
 } Hypercube;
 
 #define HYPERCUBE_SIZE(num_dimensions)									\

src/partitioning.c

@@ -95,6 +95,7 @@ partitioning_func_apply_tuple(PartitioningInfo *pinfo, HeapTuple tuple, TupleDes
 }
 
 /* _timescaledb_catalog.get_partition_for_key(key TEXT) RETURNS INT */
+PGDLLEXPORT Datum get_partition_for_key(PG_FUNCTION_ARGS);
 PG_FUNCTION_INFO_V1(get_partition_for_key);
 
 Datum

src/scanner.c

@@ -33,11 +33,11 @@ typedef struct InternalScannerCtx
  */
 typedef struct Scanner
 {
-	Relation	(*open) (InternalScannerCtx *ctx);
+	Relation	(*openheap) (InternalScannerCtx *ctx);
 	ScanDesc	(*beginscan) (InternalScannerCtx *ctx);
 	bool		(*getnext) (InternalScannerCtx *ctx);
 	void		(*endscan) (InternalScannerCtx *ctx);
-	void		(*close) (InternalScannerCtx *ctx);
+	void		(*closeheap) (InternalScannerCtx *ctx);
 } Scanner;
 
 /* Functions implementing heap scans */
@@ -127,18 +127,18 @@ index_scanner_close(InternalScannerCtx *ctx)
  */
 static Scanner scanners[] = {
 	[ScannerTypeHeap] = {
-		.open = heap_scanner_open,
+		.openheap = heap_scanner_open,
 		.beginscan = heap_scanner_beginscan,
 		.getnext = heap_scanner_getnext,
 		.endscan = heap_scanner_endscan,
-		.close = heap_scanner_close,
+		.closeheap = heap_scanner_close,
 	},
 	[ScannerTypeIndex] = {
-		.open = index_scanner_open,
+		.openheap = index_scanner_open,
 		.beginscan = index_scanner_beginscan,
 		.getnext = index_scanner_getnext,
 		.endscan = index_scanner_endscan,
-		.close = index_scanner_close,
+		.closeheap = index_scanner_close,
 	}
 };
 
@@ -159,7 +159,7 @@ scanner_scan(ScannerCtx *ctx)
 		.sctx = ctx,
 	};
 
-	scanner->open(&ictx);
+	scanner->openheap(&ictx);
 	scanner->beginscan(&ictx);
 
 	tuple_desc = RelationGetDescr(ictx.tablerel);
@@ -214,7 +214,7 @@ scanner_scan(ScannerCtx *ctx)
 		ctx->postscan(ictx.tinfo.count, ctx->data);
 
 	scanner->endscan(&ictx);
-	scanner->close(&ictx);
+	scanner->closeheap(&ictx);
 
 	return ictx.tinfo.count;
 }

src/utils.c

@@ -176,6 +176,7 @@ time_value_to_internal(Datum time_val, Oid type)
 	}
 
 	elog(ERROR, "unkown time type oid '%d'", type);
+	return -1;
 }
 
 /* Make a RangeVar from a regclass Oid */

src/utils.h

@@ -4,12 +4,14 @@
 #include "fmgr.h"
 #include "nodes/primnodes.h"
 
-extern Datum pg_timestamp_to_microseconds(PG_FUNCTION_ARGS);
-extern Datum pg_microseconds_to_timestamp(PG_FUNCTION_ARGS);
-extern Datum pg_timestamp_to_unix_microseconds(PG_FUNCTION_ARGS);
-extern Datum pg_unix_microseconds_to_timestamp(PG_FUNCTION_ARGS);
-
-extern Datum timestamp_bucket(PG_FUNCTION_ARGS);
+extern PGDLLEXPORT Datum pg_timestamp_to_microseconds(PG_FUNCTION_ARGS);
+extern PGDLLEXPORT Datum pg_microseconds_to_timestamp(PG_FUNCTION_ARGS);
+extern PGDLLEXPORT Datum pg_timestamp_to_unix_microseconds(PG_FUNCTION_ARGS);
+extern PGDLLEXPORT Datum pg_unix_microseconds_to_timestamp(PG_FUNCTION_ARGS);
+
+extern PGDLLEXPORT Datum timestamp_bucket(PG_FUNCTION_ARGS);
+extern PGDLLEXPORT Datum timestamptz_bucket(PG_FUNCTION_ARGS);
+extern PGDLLEXPORT Datum date_bucket(PG_FUNCTION_ARGS);
 
 /*
  * Convert a column value into the internal time representation.

src/version.c

@@ -4,6 +4,8 @@
 
 const char *git_commit = EXT_GIT_COMMIT;
 
+PGDLLEXPORT Datum get_git_commit(PG_FUNCTION_ARGS);
+
 PG_FUNCTION_INFO_V1(get_git_commit);
 
 Datum