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Fix oversight in commit 0dca5d6.
As coded, fmgr_sql() would get an assertion failure for a SQL function that has an empty body and is declared to return some type other than VOID. Typically you'd never get that far because fmgr_sql_validator() would reject such a definition (I suspect that's how come I managed to miss the bug). But if check_function_bodies is off or the function is polymorphic, the validation check wouldn't get made. Reported-by: Alexander Lakhin <exclusion@gmail.com> Author: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://postgr.es/m/0fde377a-3870-4d18-946a-ce008ee5bb88@gmail.com
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3 files changed

+40
-2
lines changed

3 files changed

+40
-2
lines changed

‎src/backend/executor/functions.c

Lines changed: 14 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1116,6 +1116,19 @@ sql_compile_callback(FunctionCallInfo fcinfo,
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*/
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func->num_queries = list_length(source_list);
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1119+
/*
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* Edge case: empty function body is OK only if it returns VOID. Normally
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* we validate that the last statement returns the right thing in
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* check_sql_stmt_retval, but we'll never reach that if there's no last
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* statement.
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*/
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if (func->num_queries == 0 && rettype != VOIDOID)
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ereport(ERROR,
1127+
(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
1128+
errmsg("return type mismatch in function declared to return %s",
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format_type_be(rettype)),
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errdetail("Function's final statement must be SELECT or INSERT/UPDATE/DELETE/MERGE RETURNING.")));
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11191132
/* Save the source trees in pcontext for now. */
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MemoryContextSwitchTo(pcontext);
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func->source_list = copyObject(source_list);
@@ -2103,7 +2116,7 @@ check_sql_stmt_retval(List *queryTreeList,
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}
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else
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{
2106-
/* Empty function body, or last statement is a utility command */
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/* Last statement is a utility command, or it rewrote to nothing */
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
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errmsg("return type mismatch in function declared to return %s",

‎src/test/regress/expected/create_function_sql.out

Lines changed: 16 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -757,9 +757,23 @@ LINE 2: AS 'SELECT $2;';
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CREATE FUNCTION test1 (int) RETURNS int LANGUAGE SQL
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AS 'a', 'b';
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ERROR: only one AS item needed for language "sql"
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CREATE FUNCTION test1 (int) RETURNS int LANGUAGE SQL
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AS '';
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ERROR: return type mismatch in function declared to return integer
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DETAIL: Function's final statement must be SELECT or INSERT/UPDATE/DELETE/MERGE RETURNING.
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CONTEXT: SQL function "test1"
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-- make sure empty-body case is handled at execution time, too
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SET check_function_bodies = off;
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CREATE FUNCTION test1 (anyelement) RETURNS anyarray LANGUAGE SQL
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AS '';
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SELECT test1(0);
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ERROR: return type mismatch in function declared to return integer[]
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DETAIL: Function's final statement must be SELECT or INSERT/UPDATE/DELETE/MERGE RETURNING.
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CONTEXT: SQL function "test1" during startup
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RESET check_function_bodies;
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-- Cleanup
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DROP SCHEMA temp_func_test CASCADE;
762-
NOTICE: drop cascades to 34 other objects
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NOTICE: drop cascades to 35 other objects
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DETAIL: drop cascades to function functest_a_1(text,date)
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drop cascades to function functest_a_2(text[])
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drop cascades to function functest_a_3()
@@ -794,5 +808,6 @@ drop cascades to function create_and_insert()
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drop cascades to table ddl_test
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drop cascades to function alter_and_insert()
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drop cascades to function double_append(anyarray,anyelement)
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drop cascades to function test1(anyelement)
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DROP USER regress_unpriv_user;
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RESET search_path;

‎src/test/regress/sql/create_function_sql.sql

Lines changed: 10 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -449,6 +449,16 @@ CREATE FUNCTION test1 (int) RETURNS int LANGUAGE SQL
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CREATE FUNCTION test1 (int) RETURNS int LANGUAGE SQL
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AS 'a', 'b';
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CREATE FUNCTION test1 (int) RETURNS int LANGUAGE SQL
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AS '';
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-- make sure empty-body case is handled at execution time, too
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SET check_function_bodies = off;
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CREATE FUNCTION test1 (anyelement) RETURNS anyarray LANGUAGE SQL
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AS '';
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SELECT test1(0);
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RESET check_function_bodies;
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-- Cleanup
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DROP SCHEMA temp_func_test CASCADE;
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DROP USER regress_unpriv_user;

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