Fix datatype handling for plpgsql function parameters

[svenklemm]

Currently all plpgql function parameters are returned as UNKNOWN. This patch changes function parameters to return actual type names used in the function definition.

Fixes #126

[lfittl]

@svenklemm Thanks for the contribution - @msepga will take a look at this.

[svenklemm]

@msepga any update?

[svenklemm]

@lfittl looks like @msepga is MIA

[lfittl]

@lfittl looks like @msepga is MIA

Just got a lot on our plate, but I'll make sure we can get this reviewed in the next days. Thanks for your patience!

[msepga]

Thanks for the contribution and patience, @svenklemm! The mock LGTM 👍

One note, looks like running make extract_source seemed to drop quote_qualified_identifier in the source here. I've added a call to resolve the symbol:

 # PL/pgSQL Parsing
 runner.deep_resolve('plpgsql_compile_inline')
 runner.deep_resolve('plpgsql_free_function_memory')
+runner.deep_resolve('quote_qualified_identifier')

I'll approve this PR once the tests pass with the new commit.

For reference, here's the original diff I get after running make extract_source, without the new commit:

diff --git a/src/postgres/src_backend_utils_adt_ruleutils.c b/src/postgres/src_backend_utils_adt_ruleutils.c
index 30df7c3..9257991 100644
--- a/src/postgres/src_backend_utils_adt_ruleutils.c
+++ b/src/postgres/src_backend_utils_adt_ruleutils.c
@@ -1718,18 +1718,7 @@ quote_identifier(const char *ident)
  * Return a name of the form qualifier.ident, or just ident if qualifier
  * is NULL, quoting each component if necessary.  The result is palloc'd.
  */
-char *
-quote_qualified_identifier(const char *qualifier,
-						   const char *ident)
-{
-	StringInfoData buf;
 
-	initStringInfo(&buf);
-	if (qualifier)
-		appendStringInfo(&buf, "%s.", quote_identifier(qualifier));
-	appendStringInfoString(&buf, quote_identifier(ident));
-	return buf.data;
-}
 
 /*
  * get_relation_name
diff --git a/src/postgres/src_pl_plpgsql_src_pl_comp.c b/src/postgres/src_pl_plpgsql_src_pl_comp.c
index 197de46..f99fab0 100644
--- a/src/postgres/src_pl_plpgsql_src_pl_comp.c
+++ b/src/postgres/src_pl_plpgsql_src_pl_comp.c
@@ -879,6 +879,7 @@ plpgsql_build_recfield(PLpgSQL_rec *rec, const char *fldname)
  * It can be NULL if the type could not be a composite type, or if it was
  * identified by OID to begin with (e.g., it's a function argument type).
  */
+
 PLpgSQL_type * plpgsql_build_datatype(Oid typeOid, int32 typmod, Oid collation, TypeName *origtypname)
 {
 	PLpgSQL_type *typ;
@@ -923,6 +924,8 @@ PLpgSQL_type * plpgsql_build_datatype(Oid typeOid, int32 typmod, Oid collation,
 	return typ;
 }
 
+
+
 /*
  * Utility subroutine to make a PLpgSQL_type struct given a pg_type entry
  * and additional details (see comments for plpgsql_build_datatype).