Fix PL/pgSQL's handling of integer ranges containing underscores.

Commit faff8f8e47 allowed integer literals to contain underscores, but
failed to update the lexer's "numericfail" rule. As a result, a
decimal integer literal containing underscores would fail to parse, if
used in an integer range with no whitespace after the first number,
such as "1_001..1_003" in a PL/pgSQL FOR loop.

Fix and backpatch to v16, where support for underscores in integer
literals was added.

Report and patch by Erik Wienhold.

Discussion: https://postgr.es/m/808ce947-46ec-4628-85fa-3dd600b2c154%40ewie.name

2 files changed, 20 insertions, 0 deletions

diff --git a/src/test/regress/expected/numerology.out b/src/test/regress/expected/numerology.out
index c8196d2c85a..8d4a3ba228a 100644
--- a/src/test/regress/expected/numerology.out
+++ b/src/test/regress/expected/numerology.out
@@ -297,6 +297,17 @@ SELECT 1_000.5e0_1;
     10005
 (1 row)
 
+DO $$
+DECLARE
+  i int;
+BEGIN
+  FOR i IN 1_001..1_003 LOOP
+    RAISE NOTICE 'i = %', i;
+  END LOOP;
+END $$;
+NOTICE:  i = 1001
+NOTICE:  i = 1002
+NOTICE:  i = 1003
 -- error cases
 SELECT _100;
 ERROR:  column "_100" does not exist
diff --git a/src/test/regress/sql/numerology.sql b/src/test/regress/sql/numerology.sql
index 3f0ec34ecfa..372e7bf9bc8 100644
--- a/src/test/regress/sql/numerology.sql
+++ b/src/test/regress/sql/numerology.sql
@@ -77,6 +77,15 @@ SELECT 1_000.;
 SELECT .000_005;
 SELECT 1_000.5e0_1;
 
+DO $$
+DECLARE
+  i int;
+BEGIN
+  FOR i IN 1_001..1_003 LOOP
+    RAISE NOTICE 'i = %', i;
+  END LOOP;
+END $$;
+
 -- error cases
 SELECT _100;
 SELECT 100_;