Improve ExplainState type handling in header files

Now that we can have repeat typedefs with C11, we don't need to use
"struct ExplainState" anymore but can instead make a typedef where
necessary.  This doesn't change anything but makes it look nicer.

(There are more opportunities for similar changes, but this is broken
out because there was a separate discussion about it, and it's
somewhat bulky on its own.)

Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/f36c0a45-98cd-40b2-a7cc-f2bf02b12890%40eisentraut.org#a12fb1a2c1089d6d03010f6268871b00
Discussion: https://www.postgresql.org/message-id/flat/10d32190-f31b-40a5-b177-11db55597355@eisentraut.org

5 files changed, 40 insertions, 38 deletions

diff --git a/src/include/commands/explain.h b/src/include/commands/explain.h
index 3b122f79ed8..6e51d50efc7 100644
--- a/src/include/commands/explain.h
+++ b/src/include/commands/explain.h
@@ -16,13 +16,13 @@
 #include "executor/executor.h"
 #include "parser/parse_node.h"
 
-struct ExplainState;			/* defined in explain_state.h */
+typedef struct ExplainState ExplainState;	/* defined in explain_state.h */
 
 /* Hook for plugins to get control in ExplainOneQuery() */
 typedef void (*ExplainOneQuery_hook_type) (Query *query,
 										   int cursorOptions,
 										   IntoClause *into,
-										   struct ExplainState *es,
+										   ExplainState *es,
 										   const char *queryString,
 										   ParamListInfo params,
 										   QueryEnvironment *queryEnv);
@@ -31,7 +31,7 @@ extern PGDLLIMPORT ExplainOneQuery_hook_type ExplainOneQuery_hook;
 /* Hook for EXPLAIN plugins to print extra information for each plan */
 typedef void (*explain_per_plan_hook_type) (PlannedStmt *plannedstmt,
 											IntoClause *into,
-											struct ExplainState *es,
+											ExplainState *es,
 											const char *queryString,
 											ParamListInfo params,
 											QueryEnvironment *queryEnv);
@@ -42,7 +42,7 @@ typedef void (*explain_per_node_hook_type) (PlanState *planstate,
 											List *ancestors,
 											const char *relationship,
 											const char *plan_name,
-											struct ExplainState *es);
+											ExplainState *es);
 extern PGDLLIMPORT explain_per_node_hook_type explain_per_node_hook;
 
 /* Hook for plugins to get control in explain_get_index_name() */
@@ -53,32 +53,32 @@ extern PGDLLIMPORT explain_get_index_name_hook_type explain_get_index_name_hook;
 extern void ExplainQuery(ParseState *pstate, ExplainStmt *stmt,
 						 ParamListInfo params, DestReceiver *dest);
 extern void standard_ExplainOneQuery(Query *query, int cursorOptions,
-									 IntoClause *into, struct ExplainState *es,
+									 IntoClause *into, ExplainState *es,
 									 const char *queryString, ParamListInfo params,
 									 QueryEnvironment *queryEnv);
 
 extern TupleDesc ExplainResultDesc(ExplainStmt *stmt);
 
 extern void ExplainOneUtility(Node *utilityStmt, IntoClause *into,
-							  struct ExplainState *es, ParseState *pstate,
+							  ExplainState *es, ParseState *pstate,
 							  ParamListInfo params);
 
 extern void ExplainOnePlan(PlannedStmt *plannedstmt, IntoClause *into,
-						   struct ExplainState *es, const char *queryString,
+						   ExplainState *es, const char *queryString,
 						   ParamListInfo params, QueryEnvironment *queryEnv,
 						   const instr_time *planduration,
 						   const BufferUsage *bufusage,
 						   const MemoryContextCounters *mem_counters);
 
-extern void ExplainPrintPlan(struct ExplainState *es, QueryDesc *queryDesc);
-extern void ExplainPrintTriggers(struct ExplainState *es,
+extern void ExplainPrintPlan(ExplainState *es, QueryDesc *queryDesc);
+extern void ExplainPrintTriggers(ExplainState *es,
 								 QueryDesc *queryDesc);
 
-extern void ExplainPrintJITSummary(struct ExplainState *es,
+extern void ExplainPrintJITSummary(ExplainState *es,
 								   QueryDesc *queryDesc);
 
-extern void ExplainQueryText(struct ExplainState *es, QueryDesc *queryDesc);
-extern void ExplainQueryParameters(struct ExplainState *es,
+extern void ExplainQueryText(ExplainState *es, QueryDesc *queryDesc);
+extern void ExplainQueryParameters(ExplainState *es,
 								   ParamListInfo params, int maxlen);
 
 #endif							/* EXPLAIN_H */
diff --git a/src/include/commands/explain_dr.h b/src/include/commands/explain_dr.h
index 55da63d66bd..b62f1f8542c 100644
--- a/src/include/commands/explain_dr.h
+++ b/src/include/commands/explain_dr.h
@@ -16,7 +16,8 @@
 #include "executor/instrument.h"
 #include "tcop/dest.h"
 
-struct ExplainState;			/* avoid including explain.h here */
+/* avoid including explain_state.h here */
+typedef struct ExplainState ExplainState;
 
 /* Instrumentation data for EXPLAIN's SERIALIZE option */
 typedef struct SerializeMetrics
@@ -26,7 +27,7 @@ typedef struct SerializeMetrics
 	BufferUsage bufferUsage;	/* buffers accessed during serialization */
 } SerializeMetrics;
 
-extern DestReceiver *CreateExplainSerializeDestReceiver(struct ExplainState *es);
+extern DestReceiver *CreateExplainSerializeDestReceiver(ExplainState *es);
 extern SerializeMetrics GetSerializationMetrics(DestReceiver *dest);
 
 #endif
diff --git a/src/include/commands/explain_format.h b/src/include/commands/explain_format.h
index 05045bf8cb4..f849a3938ce 100644
--- a/src/include/commands/explain_format.h
+++ b/src/include/commands/explain_format.h
@@ -15,44 +15,45 @@
 
 #include "nodes/pg_list.h"
 
-struct ExplainState;			/* avoid including explain.h here */
+/* avoid including explain_state.h here */
+typedef struct ExplainState ExplainState;
 
 extern void ExplainPropertyList(const char *qlabel, List *data,
-								struct ExplainState *es);
+								ExplainState *es);
 extern void ExplainPropertyListNested(const char *qlabel, List *data,
-									  struct ExplainState *es);
+									  ExplainState *es);
 extern void ExplainPropertyText(const char *qlabel, const char *value,
-								struct ExplainState *es);
+								ExplainState *es);
 extern void ExplainPropertyInteger(const char *qlabel, const char *unit,
-								   int64 value, struct ExplainState *es);
+								   int64 value, ExplainState *es);
 extern void ExplainPropertyUInteger(const char *qlabel, const char *unit,
-									uint64 value, struct ExplainState *es);
+									uint64 value, ExplainState *es);
 extern void ExplainPropertyFloat(const char *qlabel, const char *unit,
 								 double value, int ndigits,
-								 struct ExplainState *es);
+								 ExplainState *es);
 extern void ExplainPropertyBool(const char *qlabel, bool value,
-								struct ExplainState *es);
+								ExplainState *es);
 
 extern void ExplainOpenGroup(const char *objtype, const char *labelname,
-							 bool labeled, struct ExplainState *es);
+							 bool labeled, ExplainState *es);
 extern void ExplainCloseGroup(const char *objtype, const char *labelname,
-							  bool labeled, struct ExplainState *es);
+							  bool labeled, ExplainState *es);
 
 extern void ExplainOpenSetAsideGroup(const char *objtype, const char *labelname,
 									 bool labeled, int depth,
-									 struct ExplainState *es);
-extern void ExplainSaveGroup(struct ExplainState *es, int depth,
+									 ExplainState *es);
+extern void ExplainSaveGroup(ExplainState *es, int depth,
 							 int *state_save);
-extern void ExplainRestoreGroup(struct ExplainState *es, int depth,
+extern void ExplainRestoreGroup(ExplainState *es, int depth,
 								int *state_save);
 
 extern void ExplainDummyGroup(const char *objtype, const char *labelname,
-							  struct ExplainState *es);
+							  ExplainState *es);
 
-extern void ExplainBeginOutput(struct ExplainState *es);
-extern void ExplainEndOutput(struct ExplainState *es);
-extern void ExplainSeparatePlans(struct ExplainState *es);
+extern void ExplainBeginOutput(ExplainState *es);
+extern void ExplainEndOutput(ExplainState *es);
+extern void ExplainSeparatePlans(ExplainState *es);
 
-extern void ExplainIndentText(struct ExplainState *es);
+extern void ExplainIndentText(ExplainState *es);
 
 #endif
diff --git a/src/include/commands/explain_state.h b/src/include/commands/explain_state.h
index 32728f5d1a1..ba073b86918 100644
--- a/src/include/commands/explain_state.h
+++ b/src/include/commands/explain_state.h
@@ -79,7 +79,7 @@ typedef struct ExplainState
 typedef void (*ExplainOptionHandler) (ExplainState *, DefElem *, ParseState *);
 
 /* Hook to perform additional EXPLAIN options validation */
-typedef void (*explain_validate_options_hook_type) (struct ExplainState *es, List *options,
+typedef void (*explain_validate_options_hook_type) (ExplainState *es, List *options,
 													ParseState *pstate);
 extern PGDLLIMPORT explain_validate_options_hook_type explain_validate_options_hook;
 
diff --git a/src/include/foreign/fdwapi.h b/src/include/foreign/fdwapi.h
index b4da4e6a16a..fcd7e7027f3 100644
--- a/src/include/foreign/fdwapi.h
+++ b/src/include/foreign/fdwapi.h
@@ -16,8 +16,8 @@
 #include "nodes/execnodes.h"
 #include "nodes/pathnodes.h"
 
-/* To avoid including explain.h here, reference ExplainState thus: */
-struct ExplainState;
+/* avoid including explain_state.h here */
+typedef struct ExplainState ExplainState;
 
 
 /*
@@ -137,16 +137,16 @@ typedef void (*RefetchForeignRow_function) (EState *estate,
 											bool *updated);
 
 typedef void (*ExplainForeignScan_function) (ForeignScanState *node,
-											 struct ExplainState *es);
+											 ExplainState *es);
 
 typedef void (*ExplainForeignModify_function) (ModifyTableState *mtstate,
 											   ResultRelInfo *rinfo,
 											   List *fdw_private,
 											   int subplan_index,
-											   struct ExplainState *es);
+											   ExplainState *es);
 
 typedef void (*ExplainDirectModify_function) (ForeignScanState *node,
-											  struct ExplainState *es);
+											  ExplainState *es);
 
 typedef int (*AcquireSampleRowsFunc) (Relation relation, int elevel,
 									  HeapTuple *rows, int targrows,