Provide plpgsql tests for cases involving record field changes.

We suppressed one of these test cases in commit feb1cc559 because
it was failing to produce the expected results on CLOBBER_CACHE_ALWAYS
buildfarm members.  But now we need another test with similar behavior,
so let's set up a test file that is expected to vary between regular and
CLOBBER_CACHE_ALWAYS cases, and provide variant expected files.

Someday we should fix plpgsql's failure for change-of-field-type, and
then the discrepancy will go away and we can fold these tests back
into plpgsql_record.sql.  But today is not that day.

Discussion: https://postgr.es/m/87wotkfju1.fsf@news-spur.riddles.org.uk

src/pl/plpgsql/src/Makefile

@@ -27,7 +27,7 @@ DATA = plpgsql.control plpgsql--1.0.sql plpgsql--unpackaged--1.0.sql
 REGRESS_OPTS = --dbname=$(PL_TESTDB)
 
 REGRESS = plpgsql_call plpgsql_control plpgsql_domain plpgsql_record \
-	plpgsql_transaction plpgsql_varprops
+	plpgsql_cache plpgsql_transaction plpgsql_varprops
 
 all: all-lib
 

src/pl/plpgsql/src/expected/plpgsql_cache.out

@@ -0,0 +1,67 @@
+--
+-- Cache-behavior-dependent test cases
+--
+-- These tests logically belong in plpgsql_record.sql, and perhaps someday
+-- can be merged back into it.  For now, however, their results are different
+-- between regular and CLOBBER_CACHE_ALWAYS builds, so we must have two
+-- expected-output files to cover both cases.  To minimize the maintenance
+-- effort resulting from that, this file should contain only tests that
+-- do have different results under CLOBBER_CACHE_ALWAYS.
+--
+-- check behavior with changes of a named rowtype
+create table c_mutable(f1 int, f2 text);
+create function c_sillyaddone(int) returns int language plpgsql as
+$$ declare r c_mutable; begin r.f1 := $1; return r.f1 + 1; end $$;
+select c_sillyaddone(42);
+ c_sillyaddone 
+---------------
+            43
+(1 row)
+
+alter table c_mutable drop column f1;
+alter table c_mutable add column f1 float8;
+-- currently, this fails due to cached plan for "r.f1 + 1" expression
+-- (but a CLOBBER_CACHE_ALWAYS build will succeed)
+select c_sillyaddone(42);
+ERROR:  type of parameter 4 (double precision) does not match that when preparing the plan (integer)
+CONTEXT:  PL/pgSQL function c_sillyaddone(integer) line 1 at RETURN
+-- but it's OK if we force plan rebuilding
+discard plans;
+select c_sillyaddone(42);
+ c_sillyaddone 
+---------------
+            43
+(1 row)
+
+-- check behavior with changes in a record rowtype
+create function show_result_type(text) returns text language plpgsql as
+$$
+    declare
+        r record;
+        t text;
+    begin
+        execute $1 into r;
+        select pg_typeof(r.a) into t;
+        return format('type %s value %s', t, r.a::text);
+    end;
+$$;
+select show_result_type('select 1 as a');
+   show_result_type   
+----------------------
+ type integer value 1
+(1 row)
+
+-- currently this fails due to cached plan for pg_typeof expression
+-- (but a CLOBBER_CACHE_ALWAYS build will succeed)
+select show_result_type('select 2.0 as a');
+ERROR:  type of parameter 5 (numeric) does not match that when preparing the plan (integer)
+CONTEXT:  SQL statement "select pg_typeof(r.a)"
+PL/pgSQL function show_result_type(text) line 7 at SQL statement
+-- but it's OK if we force plan rebuilding
+discard plans;
+select show_result_type('select 2.0 as a');
+    show_result_type    
+------------------------
+ type numeric value 2.0
+(1 row)
+

src/pl/plpgsql/src/expected/plpgsql_cache_1.out

@@ -0,0 +1,72 @@
+--
+-- Cache-behavior-dependent test cases
+--
+-- These tests logically belong in plpgsql_record.sql, and perhaps someday
+-- can be merged back into it.  For now, however, their results are different
+-- between regular and CLOBBER_CACHE_ALWAYS builds, so we must have two
+-- expected-output files to cover both cases.  To minimize the maintenance
+-- effort resulting from that, this file should contain only tests that
+-- do have different results under CLOBBER_CACHE_ALWAYS.
+--
+-- check behavior with changes of a named rowtype
+create table c_mutable(f1 int, f2 text);
+create function c_sillyaddone(int) returns int language plpgsql as
+$$ declare r c_mutable; begin r.f1 := $1; return r.f1 + 1; end $$;
+select c_sillyaddone(42);
+ c_sillyaddone 
+---------------
+            43
+(1 row)
+
+alter table c_mutable drop column f1;
+alter table c_mutable add column f1 float8;
+-- currently, this fails due to cached plan for "r.f1 + 1" expression
+-- (but a CLOBBER_CACHE_ALWAYS build will succeed)
+select c_sillyaddone(42);
+ c_sillyaddone 
+---------------
+            43
+(1 row)
+
+-- but it's OK if we force plan rebuilding
+discard plans;
+select c_sillyaddone(42);
+ c_sillyaddone 
+---------------
+            43
+(1 row)
+
+-- check behavior with changes in a record rowtype
+create function show_result_type(text) returns text language plpgsql as
+$$
+    declare
+        r record;
+        t text;
+    begin
+        execute $1 into r;
+        select pg_typeof(r.a) into t;
+        return format('type %s value %s', t, r.a::text);
+    end;
+$$;
+select show_result_type('select 1 as a');
+   show_result_type   
+----------------------
+ type integer value 1
+(1 row)
+
+-- currently this fails due to cached plan for pg_typeof expression
+-- (but a CLOBBER_CACHE_ALWAYS build will succeed)
+select show_result_type('select 2.0 as a');
+    show_result_type    
+------------------------
+ type numeric value 2.0
+(1 row)
+
+-- but it's OK if we force plan rebuilding
+discard plans;
+select show_result_type('select 2.0 as a');
+    show_result_type    
+------------------------
+ type numeric value 2.0
+(1 row)
+

src/pl/plpgsql/src/expected/plpgsql_record.out

@@ -421,20 +421,8 @@ select sillyaddone(42);
           43
 (1 row)
 
-alter table mutable drop column f1;
-alter table mutable add column f1 float8;
--- currently, this fails due to cached plan for "r.f1 + 1" expression
--- (but we can't actually show that, because a CLOBBER_CACHE_ALWAYS build
--- will succeed)
--- select sillyaddone(42);
--- but it's OK if we force plan rebuilding
-discard plans;
-select sillyaddone(42);
- sillyaddone 
--------------
-          43
-(1 row)
-
+-- test for change of type of column f1 should be here someday;
+-- for now see plpgsql_cache test
 alter table mutable drop column f1;
 select sillyaddone(42);  -- fail
 ERROR:  record "r" has no field "f1"

src/pl/plpgsql/src/sql/plpgsql_cache.sql

@@ -0,0 +1,50 @@
+--
+-- Cache-behavior-dependent test cases
+--
+-- These tests logically belong in plpgsql_record.sql, and perhaps someday
+-- can be merged back into it.  For now, however, their results are different
+-- between regular and CLOBBER_CACHE_ALWAYS builds, so we must have two
+-- expected-output files to cover both cases.  To minimize the maintenance
+-- effort resulting from that, this file should contain only tests that
+-- do have different results under CLOBBER_CACHE_ALWAYS.
+--
+
+-- check behavior with changes of a named rowtype
+create table c_mutable(f1 int, f2 text);
+
+create function c_sillyaddone(int) returns int language plpgsql as
+$$ declare r c_mutable; begin r.f1 := $1; return r.f1 + 1; end $$;
+select c_sillyaddone(42);
+
+alter table c_mutable drop column f1;
+alter table c_mutable add column f1 float8;
+
+-- currently, this fails due to cached plan for "r.f1 + 1" expression
+-- (but a CLOBBER_CACHE_ALWAYS build will succeed)
+select c_sillyaddone(42);
+
+-- but it's OK if we force plan rebuilding
+discard plans;
+select c_sillyaddone(42);
+
+-- check behavior with changes in a record rowtype
+create function show_result_type(text) returns text language plpgsql as
+$$
+    declare
+        r record;
+        t text;
+    begin
+        execute $1 into r;
+        select pg_typeof(r.a) into t;
+        return format('type %s value %s', t, r.a::text);
+    end;
+$$;
+
+select show_result_type('select 1 as a');
+-- currently this fails due to cached plan for pg_typeof expression
+-- (but a CLOBBER_CACHE_ALWAYS build will succeed)
+select show_result_type('select 2.0 as a');
+
+-- but it's OK if we force plan rebuilding
+discard plans;
+select show_result_type('select 2.0 as a');

src/pl/plpgsql/src/sql/plpgsql_record.sql

@@ -270,17 +270,8 @@ create function sillyaddone(int) returns int language plpgsql as
 $$ declare r mutable; begin r.f1 := $1; return r.f1 + 1; end $$;
 select sillyaddone(42);
 
-alter table mutable drop column f1;
-alter table mutable add column f1 float8;
-
--- currently, this fails due to cached plan for "r.f1 + 1" expression
--- (but we can't actually show that, because a CLOBBER_CACHE_ALWAYS build
--- will succeed)
--- select sillyaddone(42);
-
--- but it's OK if we force plan rebuilding
-discard plans;
-select sillyaddone(42);
+-- test for change of type of column f1 should be here someday;
+-- for now see plpgsql_cache test
 
 alter table mutable drop column f1;
 select sillyaddone(42);  -- fail