Add a testing case for a decimal number with a leading zero

That syntax is invalid, since decimal numbers should never have a
leading zero and octal numbers use the `0o` prefix instead.

This matches Python 3 syntax which does not accept it:

  $ python3
  >>> 0123
    File "<stdin>", line 1
      0123
         ^
  SyntaxError: invalid token
  >>>

Add a "failing" test case to confirm this property is preserved and no
regressions are introduced in this area.

1 files changed, 6 insertions, 0 deletions

diff --git a/test cases/failing/76 int literal leading zero/meson.build b/test cases/failing/76 int literal leading zero/meson.build
new file mode 100644
index 0000000..7ad64ae
--- /dev/null
+++ b/test cases/failing/76 int literal leading zero/meson.build
@@ -0,0 +1,6 @@
+
+# This should fail.
+# Decimal syntax is 123.
+# Octal syntax is 0o123.
+fail_0123 = 0123
+