Get rid of COERCE_DONTCARE.

We don't need this hack any more.

src/backend/executor/functions.c

@@ -1572,7 +1572,7 @@ check_sql_fn_retval(Oid func_id, Oid rettype, List *queryTreeList,
 												 rettype,
 												 -1,
 												 get_typcollation(rettype),
-												 COERCE_DONTCARE);
+												 COERCE_IMPLICIT_CAST);
 			/* Relabel is dangerous if TLE is a sort/group or setop column */
 			if (tle->ressortgroupref != 0 || parse->setOperations)
 				*modifyTargetList = true;
@@ -1618,7 +1618,7 @@ check_sql_fn_retval(Oid func_id, Oid rettype, List *queryTreeList,
 														 rettype,
 														 -1,
 												   get_typcollation(rettype),
-														 COERCE_DONTCARE);
+														 COERCE_IMPLICIT_CAST);
 					/* Relabel is dangerous if sort/group or setop column */
 					if (tle->ressortgroupref != 0 || parse->setOperations)
 						*modifyTargetList = true;
@@ -1722,7 +1722,7 @@ check_sql_fn_retval(Oid func_id, Oid rettype, List *queryTreeList,
 														 atttype,
 														 -1,
 												   get_typcollation(atttype),
-														 COERCE_DONTCARE);
+														 COERCE_IMPLICIT_CAST);
 					/* Relabel is dangerous if sort/group or setop column */
 					if (tle->ressortgroupref != 0 || parse->setOperations)
 						*modifyTargetList = true;

src/backend/nodes/nodeFuncs.c

@@ -554,8 +554,7 @@ exprIsLengthCoercion(const Node *expr, int32 *coercedTypmod)
  *
  * This is primarily intended to be used during planning.  Therefore, it
  * strips any existing RelabelType nodes to maintain the planner's invariant
- * that there are not adjacent RelabelTypes, and it uses COERCE_DONTCARE
- * which would typically be inappropriate earlier.
+ * that there are not adjacent RelabelTypes.
  */
 Node *
 relabel_to_typmod(Node *expr, int32 typmod)
@@ -569,7 +568,7 @@ relabel_to_typmod(Node *expr, int32 typmod)
 
 	/* Apply new typmod, preserving the previous exposed type and collation */
 	return (Node *) makeRelabelType((Expr *) expr, type, typmod, coll,
-									COERCE_DONTCARE);
+									COERCE_EXPLICIT_CAST);
 }
 
 /*

src/backend/optimizer/path/equivclass.c

@@ -431,13 +431,13 @@ canonicalize_ec_expression(Expr *expr, Oid req_type, Oid req_collation)
 											req_type,
 											-1,
 											req_collation,
-											COERCE_DONTCARE);
+											COERCE_IMPLICIT_CAST);
 		else if (exprCollation((Node *) expr) != req_collation)
 			expr = (Expr *) makeRelabelType(expr,
 											req_type,
 											exprTypmod((Node *) expr),
 											req_collation,
-											COERCE_DONTCARE);
+											COERCE_IMPLICIT_CAST);
 	}
 
 	return expr;

src/backend/optimizer/prep/prepunion.c

@@ -982,7 +982,7 @@ generate_setop_tlist(List *colTypes, List *colCollations,
 											exprType(expr),
 											exprTypmod(expr),
 											colColl,
-											COERCE_DONTCARE);
+											COERCE_IMPLICIT_CAST);
 		}
 
 		tle = makeTargetEntry((Expr *) expr,

src/backend/optimizer/util/clauses.c

@@ -2789,7 +2789,7 @@ eval_const_expressions_mutator(Node *node,
 					relabel->resulttype = exprType(arg);
 					relabel->resulttypmod = exprTypmod(arg);
 					relabel->resultcollid = collate->collOid;
-					relabel->relabelformat = COERCE_DONTCARE;
+					relabel->relabelformat = COERCE_IMPLICIT_CAST;
 					relabel->location = collate->location;
 
 					/* Don't create stacked RelabelTypes */
@@ -3625,7 +3625,7 @@ simplify_function(Oid funcid, Oid result_type, int32 result_typmod,
 		fexpr.funcid = funcid;
 		fexpr.funcresulttype = result_type;
 		fexpr.funcretset = func_form->proretset;
-		fexpr.funcformat = COERCE_DONTCARE;
+		fexpr.funcformat = COERCE_EXPLICIT_CALL;
 		fexpr.funccollid = result_collid;
 		fexpr.inputcollid = input_collid;
 		fexpr.args = args;
@@ -3959,7 +3959,7 @@ evaluate_function(Oid funcid, Oid result_type, int32 result_typmod,
 	newexpr->funcid = funcid;
 	newexpr->funcresulttype = result_type;
 	newexpr->funcretset = false;
-	newexpr->funcformat = COERCE_DONTCARE;		/* doesn't matter */
+	newexpr->funcformat = COERCE_EXPLICIT_CALL;	/* doesn't matter */
 	newexpr->funccollid = result_collid;		/* doesn't matter */
 	newexpr->inputcollid = input_collid;
 	newexpr->args = args;
@@ -4089,7 +4089,7 @@ inline_function(Oid funcid, Oid result_type, Oid result_collid,
 	fexpr->funcid = funcid;
 	fexpr->funcresulttype = result_type;
 	fexpr->funcretset = false;
-	fexpr->funcformat = COERCE_DONTCARE;		/* doesn't matter */
+	fexpr->funcformat = COERCE_EXPLICIT_CALL;	/* doesn't matter */
 	fexpr->funccollid = result_collid;	/* doesn't matter */
 	fexpr->inputcollid = input_collid;
 	fexpr->args = args;

src/backend/parser/parse_agg.c

@@ -1001,7 +1001,7 @@ build_aggregate_fnexprs(Oid *agg_input_types,
 										 args,
 										 InvalidOid,
 										 agg_input_collation,
-										 COERCE_DONTCARE);
+										 COERCE_EXPLICIT_CALL);
 
 	/* see if we have a final function */
 	if (!OidIsValid(finalfn_oid))
@@ -1027,5 +1027,5 @@ build_aggregate_fnexprs(Oid *agg_input_types,
 										 args,
 										 InvalidOid,
 										 agg_input_collation,
-										 COERCE_DONTCARE);
+										 COERCE_EXPLICIT_CALL);
 }

src/include/nodes/primnodes.h

@@ -316,7 +316,7 @@ typedef enum CoercionContext
 } CoercionContext;
 
 /*
- * CoercionForm - information showing how to display a function-call node
+ * CoercionForm - how to display a node that could have come from a cast
  *
  * NB: equal() ignores CoercionForm fields, therefore this *must* not carry
  * any semantically significant information.  We need that behavior so that
@@ -328,8 +328,7 @@ typedef enum CoercionForm
 {
 	COERCE_EXPLICIT_CALL,		/* display as a function call */
 	COERCE_EXPLICIT_CAST,		/* display as an explicit cast */
-	COERCE_IMPLICIT_CAST,		/* implicit cast, so hide it */
-	COERCE_DONTCARE				/* special case for planner */
+	COERCE_IMPLICIT_CAST		/* implicit cast, so hide it */
 } CoercionForm;
 
 /*