Don't rely on gcc-specific features (#1963)

* Don't use expressions inside compound statements
* Don't depend on __builtin_constant_p
* Remove reliance on S_ISLNK
* Replace use of __func__: older mcvs doesn't support this builtin

src/backend/distributed/utils/citus_nodefuncs.c

@@ -44,6 +44,8 @@ static const char *CitusNodeTagNamesD[] = {
 
 const char **CitusNodeTagNames = CitusNodeTagNamesD;
 
+/* support for CitusNewNode() macro */
+CitusNode *newCitusNodeMacroHolder;
 
 /* exports for SQL callable functions */
 PG_FUNCTION_INFO_V1(citus_extradata_container);

src/backend/distributed/worker/worker_partition_protocol.c

@@ -73,6 +73,7 @@ static void OutputBinaryHeaders(FileOutputStream *partitionFileArray, uint32 fil
 static void OutputBinaryFooters(FileOutputStream *partitionFileArray, uint32 fileCount);
 static uint32 RangePartitionId(Datum partitionValue, const void *context);
 static uint32 HashPartitionId(Datum partitionValue, const void *context);
+static bool FileIsLink(char *filename, struct stat filestat);
 
 
 /* exports for SQL callable functions */
@@ -614,6 +615,25 @@ CitusCreateDirectory(StringInfo directoryName)
 }
 
 
+#ifdef WIN32
+static bool
+FileIsLink(char *filename, struct stat filestat)
+{
+	return pgwin32_is_junction(filename);
+}
+
+
+#else
+static bool
+FileIsLink(char *filename, struct stat filestat)
+{
+	return S_ISLNK(filestat.st_mode);
+}
+
+
+#endif
+
+
 /*
  * CitusRemoveDirectory first checks if the given directory exists. If it does, the
  * function recursively deletes the contents of the given directory, and then
@@ -645,7 +665,7 @@ CitusRemoveDirectory(StringInfo filename)
 	 * content, recurse into this function. Also, make sure that we do not
 	 * recurse into symbolic links.
 	 */
-	if (S_ISDIR(fileStat.st_mode) && !S_ISLNK(fileStat.st_mode))
+	if (S_ISDIR(fileStat.st_mode) && !FileIsLink(filename->data, fileStat))
 	{
 		const char *directoryName = filename->data;
 		struct dirent *directoryEntry = NULL;

src/include/distributed/citus_nodes.h

@@ -89,6 +89,11 @@ CitusNodeTagI(Node *node)
 	return ((CitusNode*)(node))->citus_tag;
 }
 
+/*
+ * Postgres's nodes/nodes.h has more information on why we do this.
+ */
+#ifdef __GNUC__
+
 /* Citus variant of newNode(), don't use directly. */
 #define CitusNewNode(size, tag) \
 ({	CitusNode   *_result; \
@@ -100,6 +105,22 @@ CitusNodeTagI(Node *node)
 	_result; \
 })
 
+#else
+
+extern CitusNode *newCitusNodeMacroHolder;
+
+#define CitusNewNode(size, tag) \
+( \
+	AssertMacro((size) >= sizeof(CitusNode)),		/* need the tag, at least */ \
+	newCitusNodeMacroHolder = (CitusNode *) palloc0fast(size), \
+	newCitusNodeMacroHolder->extensible.type = T_ExtensibleNode, \
+	newCitusNodeMacroHolder->extensible.extnodename = CitusNodeTagNames[tag - CITUS_NODE_TAG_START], \
+	newCitusNodeMacroHolder->citus_tag =(int) (tag), \
+	newCitusNodeMacroHolder \
+)
+
+#endif
+
 
 /*
  * IsA equivalent that compares node tags, including Citus-specific nodes.

src/include/distributed/errormessage.h

@@ -11,6 +11,7 @@
 #define ERRORMESSAGE_H
 
 
+#include "c.h"
 #include "distributed/citus_nodes.h"
 
 
@@ -34,7 +35,8 @@ typedef struct DeferredErrorMessage
  * serialized/copied/deserialized, i.e. can be embedded in plans and such.
  */
 #define DeferredError(code, message, detail, hint) \
-	DeferredErrorInternal(code, message, detail, hint, __FILE__, __LINE__, __func__)
+	DeferredErrorInternal(code, message, detail, hint, __FILE__, __LINE__, \
+						  PG_FUNCNAME_MACRO)
 
 DeferredErrorMessage * DeferredErrorInternal(int code, const char *message, const
 											 char *detail, const char *hint,
@@ -48,12 +50,22 @@ DeferredErrorMessage * DeferredErrorInternal(int code, const char *message, cons
  * The trickery with __builtin_constant_p/pg_unreachable aims to have the
  * compiler understand that the function will not return if elevel >= ERROR.
  */
+#ifdef HAVE__BUILTIN_CONSTANT_P
 #define RaiseDeferredError(error, elevel) \
 	do { \
 		RaiseDeferredErrorInternal(error, elevel); \
 		if (__builtin_constant_p(elevel) && (elevel) >= ERROR) { \
 			pg_unreachable(); } \
 	} while (0)
+#else  /* !HAVE_BUILTIN_CONSTANT_P */
+#define RaiseDeferredError(error, elevel) \
+	do { \
+		const int elevel_ = (elevel); \
+		RaiseDeferredErrorInternal(error, elevel_); \
+		if (elevel_ >= ERROR) { \
+			pg_unreachable(); } \
+	} while (0)
+#endif /* HAVE_BUILTIN_CONSTANT_P */
 
 void RaiseDeferredErrorInternal(DeferredErrorMessage *error, int elevel);