From 7e3587034d17dd75838110bb3236816161bcd3f7 Mon Sep 17 00:00:00 2001
From: Joanna Hulboj <joanna.hulboj@gmail.com>
Date: Thu, 12 Oct 2023 19:49:06 +0100
Subject: [PATCH] Consume leading zeroes when parsing a number in
 ConstantExpressionTemplate

---
 .../Formats/Impl/ConstantExpressionTemplate.cpp   |  4 ++++
 .../02896_leading_zeroes_no_octal.reference       | 15 +++++++++++++++
 .../0_stateless/02896_leading_zeroes_no_octal.sql |  8 ++++++++
 3 files changed, 27 insertions(+)
 create mode 100644 tests/queries/0_stateless/02896_leading_zeroes_no_octal.reference
 create mode 100644 tests/queries/0_stateless/02896_leading_zeroes_no_octal.sql

diff --git a/src/Processors/Formats/Impl/ConstantExpressionTemplate.cpp b/src/Processors/Formats/Impl/ConstantExpressionTemplate.cpp
index fe6fb42d0a0..c2b0ce3e486 100644
--- a/src/Processors/Formats/Impl/ConstantExpressionTemplate.cpp
+++ b/src/Processors/Formats/Impl/ConstantExpressionTemplate.cpp
@@ -597,6 +597,10 @@ bool ConstantExpressionTemplate::parseLiteralAndAssertType(
             if (negative || *istr.position() == '+')
                 ++istr.position();
 
+            /// Consume leading zeroes - we don't want any funny octal business
+            while (*istr.position() == '0')
+                ++istr.position();
+
             static constexpr size_t MAX_LENGTH_OF_NUMBER = 319;
             char buf[MAX_LENGTH_OF_NUMBER + 1];
             size_t bytes_to_copy = std::min(istr.available(), MAX_LENGTH_OF_NUMBER);
diff --git a/tests/queries/0_stateless/02896_leading_zeroes_no_octal.reference b/tests/queries/0_stateless/02896_leading_zeroes_no_octal.reference
new file mode 100644
index 00000000000..5982c315878
--- /dev/null
+++ b/tests/queries/0_stateless/02896_leading_zeroes_no_octal.reference
@@ -0,0 +1,15 @@
+-0.02	0
+0	0
+0.01	0
+0.02	1
+0.03	1
+0.04	-1
+1	1
+2	5
+3	8
+4	17
+5	21
+6	51
+7	123
+8	16
+9	43981
diff --git a/tests/queries/0_stateless/02896_leading_zeroes_no_octal.sql b/tests/queries/0_stateless/02896_leading_zeroes_no_octal.sql
new file mode 100644
index 00000000000..fbb931b4c88
--- /dev/null
+++ b/tests/queries/0_stateless/02896_leading_zeroes_no_octal.sql
@@ -0,0 +1,8 @@
+DROP TABLE IF EXISTS t_leading_zeroes;
+CREATE TABLE t_leading_zeroes(ref Float64, val INTEGER) ENGINE=MergeTree ORDER BY ref;
+
+INSERT INTO t_leading_zeroes VALUES (-0.02, 00000), (0, 0), (0.01, 00), (0.02, 01), (0.03, +01), (0.04, -01), (1, 0001), (2, 0005), (3, 0008), (4, 0017), (5, 0021), (6, 0051), (7, 00000123), (8, 0b10000), (9, 0x0abcd);
+
+SELECT * FROM t_leading_zeroes;
+
+DROP TABLE IF EXISTS t_leading_zeroes;