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diff --git a/src/test/regress/sql/case.sql b/src/test/regress/sql/case.sql
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+--
+-- CASE
+-- Test the case statement
+--
+
+CREATE TABLE CASE_TBL (
+  i integer,
+  f double precision
+);
+
+CREATE TABLE CASE2_TBL (
+  i integer,
+  j integer
+);
+
+INSERT INTO CASE_TBL VALUES (1, 10.1);
+INSERT INTO CASE_TBL VALUES (2, 20.2);
+INSERT INTO CASE_TBL VALUES (3, -30.3);
+INSERT INTO CASE_TBL VALUES (4, NULL);
+
+INSERT INTO CASE2_TBL VALUES (1, -1);
+INSERT INTO CASE2_TBL VALUES (2, -2);
+INSERT INTO CASE2_TBL VALUES (3, -3);
+INSERT INTO CASE2_TBL VALUES (2, -4);
+INSERT INTO CASE2_TBL VALUES (1, NULL);
+INSERT INTO CASE2_TBL VALUES (NULL, -6);
+
+--
+-- Simplest examples without tables
+--
+
+SELECT '3' AS "One",
+  CASE
+    WHEN 1 < 2 THEN 3
+  END AS "Simple WHEN";
+
+SELECT '<NULL>' AS "One",
+  CASE
+    WHEN 1 > 2 THEN 3
+  END AS "Simple default";
+
+SELECT '3' AS "One",
+  CASE
+    WHEN 1 < 2 THEN 3
+    ELSE 4
+  END AS "Simple ELSE";
+
+SELECT '4' AS "One",
+  CASE
+    WHEN 1 > 2 THEN 3
+    ELSE 4
+  END AS "ELSE default";
+
+SELECT '6' AS "One",
+  CASE
+    WHEN 1 > 2 THEN 3
+    WHEN 4 < 5 THEN 6
+    ELSE 7
+  END AS "Two WHEN with default";
+
+
+SELECT '7' AS "None",
+   CASE WHEN random() < 0 THEN 1
+   END AS "NULL on no matches";
+
+-- Constant-expression folding shouldn't evaluate unreachable subexpressions
+SELECT CASE WHEN 1=0 THEN 1/0 WHEN 1=1 THEN 1 ELSE 2/0 END;
+SELECT CASE 1 WHEN 0 THEN 1/0 WHEN 1 THEN 1 ELSE 2/0 END;
+
+-- However we do not currently suppress folding of potentially
+-- reachable subexpressions
+SELECT CASE WHEN i > 100 THEN 1/0 ELSE 0 END FROM case_tbl;
+
+-- Test for cases involving untyped literals in test expression
+SELECT CASE 'a' WHEN 'a' THEN 1 ELSE 2 END;
+
+--
+-- Examples of targets involving tables
+--
+
+SELECT
+  CASE
+    WHEN i >= 3 THEN i
+  END AS ">= 3 or Null"
+  FROM CASE_TBL;
+
+SELECT
+  CASE WHEN i >= 3 THEN (i + i)
+       ELSE i
+  END AS "Simplest Math"
+  FROM CASE_TBL;
+
+SELECT i AS "Value",
+  CASE WHEN (i < 0) THEN 'small'
+       WHEN (i = 0) THEN 'zero'
+       WHEN (i = 1) THEN 'one'
+       WHEN (i = 2) THEN 'two'
+       ELSE 'big'
+  END AS "Category"
+  FROM CASE_TBL;
+
+SELECT
+  CASE WHEN ((i < 0) or (i < 0)) THEN 'small'
+       WHEN ((i = 0) or (i = 0)) THEN 'zero'
+       WHEN ((i = 1) or (i = 1)) THEN 'one'
+       WHEN ((i = 2) or (i = 2)) THEN 'two'
+       ELSE 'big'
+  END AS "Category"
+  FROM CASE_TBL;
+
+--
+-- Examples of qualifications involving tables
+--
+
+--
+-- NULLIF() and COALESCE()
+-- Shorthand forms for typical CASE constructs
+--  defined in the SQL standard.
+--
+
+SELECT * FROM CASE_TBL WHERE COALESCE(f,i) = 4;
+
+SELECT * FROM CASE_TBL WHERE NULLIF(f,i) = 2;
+
+SELECT COALESCE(a.f, b.i, b.j)
+  FROM CASE_TBL a, CASE2_TBL b;
+
+SELECT *
+  FROM CASE_TBL a, CASE2_TBL b
+  WHERE COALESCE(a.f, b.i, b.j) = 2;
+
+SELECT NULLIF(a.i,b.i) AS "NULLIF(a.i,b.i)",
+  NULLIF(b.i, 4) AS "NULLIF(b.i,4)"
+  FROM CASE_TBL a, CASE2_TBL b;
+
+SELECT *
+  FROM CASE_TBL a, CASE2_TBL b
+  WHERE COALESCE(f,b.i) = 2;
+
+-- Tests for constant subexpression simplification
+
+explain (costs off)
+SELECT * FROM CASE_TBL WHERE NULLIF(1, 2) = 2;
+
+explain (costs off)
+SELECT * FROM CASE_TBL WHERE NULLIF(1, 1) IS NOT NULL;
+
+explain (costs off)
+SELECT * FROM CASE_TBL WHERE NULLIF(1, null) = 2;
+
+--
+-- Examples of updates involving tables
+--
+
+UPDATE CASE_TBL
+  SET i = CASE WHEN i >= 3 THEN (- i)
+                ELSE (2 * i) END;
+
+SELECT * FROM CASE_TBL;
+
+UPDATE CASE_TBL
+  SET i = CASE WHEN i >= 2 THEN (2 * i)
+                ELSE (3 * i) END;
+
+SELECT * FROM CASE_TBL;
+
+UPDATE CASE_TBL
+  SET i = CASE WHEN b.i >= 2 THEN (2 * j)
+                ELSE (3 * j) END
+  FROM CASE2_TBL b
+  WHERE j = -CASE_TBL.i;
+
+SELECT * FROM CASE_TBL;
+
+--
+-- Nested CASE expressions
+--
+
+-- This test exercises a bug caused by aliasing econtext->caseValue_isNull
+-- with the isNull argument of the inner CASE's CaseExpr evaluation.  After
+-- evaluating the vol(null) expression in the inner CASE's second WHEN-clause,
+-- the isNull flag for the case test value incorrectly became true, causing
+-- the third WHEN-clause not to match.  The volatile function calls are needed
+-- to prevent constant-folding in the planner, which would hide the bug.
+
+-- Wrap this in a single transaction so the transient '=' operator doesn't
+-- cause problems in concurrent sessions
+BEGIN;
+
+CREATE FUNCTION vol(text) returns text as
+  'begin return $1; end' language plpgsql volatile;
+
+SELECT CASE
+  (CASE vol('bar')
+    WHEN 'foo' THEN 'it was foo!'
+    WHEN vol(null) THEN 'null input'
+    WHEN 'bar' THEN 'it was bar!' END
+  )
+  WHEN 'it was foo!' THEN 'foo recognized'
+  WHEN 'it was bar!' THEN 'bar recognized'
+  ELSE 'unrecognized' END;
+
+-- In this case, we can't inline the SQL function without confusing things.
+CREATE DOMAIN foodomain AS text;
+
+CREATE FUNCTION volfoo(text) returns foodomain as
+  'begin return $1::foodomain; end' language plpgsql volatile;
+
+CREATE FUNCTION inline_eq(foodomain, foodomain) returns boolean as
+  'SELECT CASE $2::text WHEN $1::text THEN true ELSE false END' language sql;
+
+CREATE OPERATOR = (procedure = inline_eq,
+                   leftarg = foodomain, rightarg = foodomain);
+
+SELECT CASE volfoo('bar') WHEN 'foo'::foodomain THEN 'is foo' ELSE 'is not foo' END;
+
+ROLLBACK;
+
+-- Test multiple evaluation of a CASE arg that is a read/write object (#14472)
+-- Wrap this in a single transaction so the transient '=' operator doesn't
+-- cause problems in concurrent sessions
+BEGIN;
+
+CREATE DOMAIN arrdomain AS int[];
+
+CREATE FUNCTION make_ad(int,int) returns arrdomain as
+  'declare x arrdomain;
+   begin
+     x := array[$1,$2];
+     return x;
+   end' language plpgsql volatile;
+
+CREATE FUNCTION ad_eq(arrdomain, arrdomain) returns boolean as
+  'begin return array_eq($1, $2); end' language plpgsql;
+
+CREATE OPERATOR = (procedure = ad_eq,
+                   leftarg = arrdomain, rightarg = arrdomain);
+
+SELECT CASE make_ad(1,2)
+  WHEN array[2,4]::arrdomain THEN 'wrong'
+  WHEN array[2,5]::arrdomain THEN 'still wrong'
+  WHEN array[1,2]::arrdomain THEN 'right'
+  END;
+
+ROLLBACK;
+
+-- Test interaction of CASE with ArrayCoerceExpr (bug #15471)
+BEGIN;
+
+CREATE TYPE casetestenum AS ENUM ('e', 'f', 'g');
+
+SELECT
+  CASE 'foo'::text
+    WHEN 'foo' THEN ARRAY['a', 'b', 'c', 'd'] || enum_range(NULL::casetestenum)::text[]
+    ELSE ARRAY['x', 'y']
+    END;
+
+ROLLBACK;
+
+--
+-- Clean up
+--
+
+DROP TABLE CASE_TBL;
+DROP TABLE CASE2_TBL;