vim-patch:9.0.1704: Cannot use positional arguments for printf() (#24719)

Problem: Cannot use positional arguments for printf()
Solution: Support positional arguments in string formatting

closes: vim/vim#12140

https://github.com/vim/vim/commit/0c6181fec4c362eb9682d5af583341eb20cb1af5

Co-authored-by: Christ van Willegen <cvwillegen@gmail.com>

4 files changed, 442 insertions, 33 deletions

diff --git a/test/old/testdir/test_expr.vim b/test/old/testdir/test_expr.vim
index 4cb8da8c74..bf1ba240eb 100644
--- a/test/old/testdir/test_expr.vim
+++ b/test/old/testdir/test_expr.vim
@@ -239,6 +239,8 @@ func Test_printf_misc()
   let lines =<< trim END
       call assert_equal('123', printf('123'))
 
+      call assert_equal('', printf('%'))
+      call assert_equal('', printf('%.0d', 0))
       call assert_equal('123', printf('%d', 123))
       call assert_equal('123', printf('%i', 123))
       call assert_equal('123', printf('%D', 123))
diff --git a/test/old/testdir/test_format.vim b/test/old/testdir/test_format.vim
new file mode 100644
index 0000000000..eae8af7b92
--- /dev/null
+++ b/test/old/testdir/test_format.vim
@@ -0,0 +1,361 @@
+" Tests for expressions.
+
+source check.vim
+source vim9.vim
+
+func Test_printf_pos_misc()
+  let lines =<< trim END
+      call assert_equal('123', printf('%1$d', 123))
+      call assert_equal('', printf('%1$.0d', 0))
+      call assert_equal('00005', printf('%1$5.5d', 5))
+      call assert_equal('00005', printf('%1$*1$.5d', 5))
+      call assert_equal('00005', printf('%1$5.*1$d', 5))
+      call assert_equal('00005', printf('%1$*1$.*1$d', 5))
+      call assert_equal('00005', printf('%1$*10$.5d%2$.0d%3$.0d%4$.0d%5$.0d%6$.0d%7$.0d%8$.0d%9$.0d', 5, 0, 0, 0, 0, 0, 0, 0, 0, 5))
+      call assert_equal('00005', printf('%1$5.*10$d%2$.0d%3$.0d%4$.0d%5$.0d%6$.0d%7$.0d%8$.0d%9$.0d', 5, 0, 0, 0, 0, 0, 0, 0, 0, 5))
+      call assert_equal('123', printf('%1$i', 123))
+      call assert_equal('123', printf('%1$D', 123))
+      call assert_equal('123', printf('%1$U', 123))
+      call assert_equal('173', printf('%1$o', 123))
+      call assert_equal('173', printf('%1$O', 123))
+      call assert_equal('7b', printf('%1$x', 123))
+      call assert_equal('7B', printf('%1$X', 123))
+      call assert_equal('Printing 1 at width 1 gives: 1', 1->printf("Printing %1$d at width %1$d gives: %1$*1$d"))
+      call assert_equal('Printing 2 at width 2 gives:  2', 2->printf("Printing %1$d at width %1$d gives: %1$*1$d"))
+      call assert_equal('Printing 3 at width 3 gives:   3', 3->printf("Printing %1$d at width %1$d gives: %1$*1$d"))
+      call assert_equal('Printing 1 at width/precision 1.1 gives: 1', 1->printf("Printing %1$d at width/precision %1$d.%1$d gives: %1$*1$.*1$d"))
+      call assert_equal('Printing 2 at width/precision 2.2 gives: 02', 2->printf("Printing %1$d at width/precision %1$d.%1$d gives: %1$*1$.*1$d"))
+      call assert_equal('Printing 3 at width/precision 3.3 gives: 003', 3->printf("Printing %1$d at width/precision %1$d.%1$d gives: %1$*1$.*1$d"))
+
+      call assert_equal('123', printf('%1$hd', 123))
+      call assert_equal('-123', printf('%1$hd', -123))
+      call assert_equal('-1', printf('%1$hd', 0xFFFF))
+      call assert_equal('-1', printf('%1$hd', 0x1FFFFF))
+
+      call assert_equal('123', printf('%1$hu', 123))
+      call assert_equal('65413', printf('%1$hu', -123))
+      call assert_equal('65535', printf('%1$hu', 0xFFFF))
+      call assert_equal('65535', printf('%1$hu', 0x1FFFFF))
+
+      call assert_equal('123', printf('%1$ld', 123))
+      call assert_equal('-123', printf('%1$ld', -123))
+      call assert_equal('65535', printf('%1$ld', 0xFFFF))
+      call assert_equal('131071', printf('%1$ld', 0x1FFFF))
+
+      call assert_equal('{', printf('%1$c', 123))
+      call assert_equal('abc', printf('%1$s', 'abc'))
+      call assert_equal('abc', printf('%1$S', 'abc'))
+
+      call assert_equal('+123', printf('%1$+d', 123))
+      call assert_equal('-123', printf('%1$+d', -123))
+      call assert_equal('+123', printf('%1$+ d', 123))
+      call assert_equal(' 123', printf('%1$ d', 123))
+      call assert_equal(' 123', printf('%1$  d', 123))
+      call assert_equal('-123', printf('%1$ d', -123))
+
+      call assert_equal('  123', printf('%2$*1$d', 5, 123))
+      call assert_equal('123  ', printf('%2$*1$d', -5, 123))
+      call assert_equal('00123', printf('%2$.*1$d', 5, 123))
+      call assert_equal('  123', printf('%2$ *1$d', 5, 123))
+      call assert_equal(' +123', printf('%2$+ *1$d', 5, 123))
+
+      call assert_equal('  123', printf('%1$*2$d', 123, 5))
+      call assert_equal('123  ', printf('%1$*2$d', 123, -5))
+      call assert_equal('00123', printf('%1$.*2$d', 123, 5))
+      call assert_equal('  123', printf('%1$ *2$d', 123, 5))
+      call assert_equal(' +123', printf('%1$+ *2$d', 123, 5))
+
+      call assert_equal('foobar', printf('%2$.*1$s',  9, 'foobar'))
+      call assert_equal('foo',    printf('%2$.*1$s',  3, 'foobar'))
+      call assert_equal('',       printf('%2$.*1$s',  0, 'foobar'))
+      call assert_equal('foobar', printf('%2$.*1$s', -1, 'foobar'))
+
+      #" Unrecognized format specifier kept as-is.
+      call assert_equal('_123', printf("%_%1$d", 123))
+
+      #" Test alternate forms.
+      call assert_equal('0x7b', printf('%1$#x', 123))
+      call assert_equal('0X7B', printf('%1$#X', 123))
+      call assert_equal('0173', printf('%1$#o', 123))
+      call assert_equal('0173', printf('%1$#O', 123))
+      call assert_equal('abc', printf('%1$#s', 'abc'))
+      call assert_equal('abc', printf('%1$#S', 'abc'))
+
+      call assert_equal('1%', printf('%1$d%%', 1))
+      call assert_notequal('', printf('%1$p', "abc"))
+      call assert_notequal('', printf('%2$d %1$p %3$s', "abc", 2, "abc"))
+
+      #" Try argument re-use and argument swapping
+      call assert_equal('one two one', printf('%1$s %2$s %1$s', "one", "two"))
+      call assert_equal('Screen height: 400', printf('%1$s height: %2$d', "Screen", 400))
+      call assert_equal('400 is: Screen height', printf('%2$d is: %1$s height', "Screen", 400))
+
+      #" Try out lots of combinations of argument types to skip
+      call assert_equal('9 12345 7654321', printf('%2$ld %1$d %3$lu', 12345, 9, 7654321))
+      call assert_equal('9 1234567 7654321', printf('%2$d %1$ld %3$lu', 1234567, 9, 7654321))
+      call assert_equal('9 1234567 7654321', printf('%2$d %1$lld %3$lu', 1234567, 9, 7654321))
+      call assert_equal('9 12345 7654321', printf('%2$ld %1$u %3$lu', 12345, 9, 7654321))
+      call assert_equal('9 1234567 7654321', printf('%2$d %1$lu %3$lu', 1234567, 9, 7654321))
+      call assert_equal('9 1234567 7654321', printf('%2$d %1$llu %3$lu', 1234567, 9, 7654321))
+      call assert_equal('9 1234567 7654321', printf('%2$d %1$llu %3$lu', 1234567, 9, 7654321))
+      call assert_equal('9 deadbeef 7654321', printf('%2$d %1$x %3$lu', 0xdeadbeef, 9, 7654321))
+      call assert_equal('9 c 7654321', printf('%2$ld %1$c %3$lu', 99, 9, 7654321))
+      call assert_equal('9 hi 7654321', printf('%2$ld %1$s %3$lu', "hi", 9, 7654321))
+      call assert_equal('9 0.000000e+00 7654321', printf('%2$ld %1$e %3$lu', 0.0, 9, 7654321))
+  END
+  call CheckLegacyAndVim9Success(lines)
+
+  call CheckLegacyAndVim9Failure(["call printf('%1$d%2$d', 1, 3, 4)"], "E767:")
+
+  call CheckLegacyAndVim9Failure(["call printf('%2$d%d', 1, 3)"], "E1400:")
+  call CheckLegacyAndVim9Failure(["call printf('%d%2$d', 1, 3)"], "E1400:")
+  call CheckLegacyAndVim9Failure(["call printf('%2$*1$d%d', 1, 3)"], "E1400:")
+  call CheckLegacyAndVim9Failure(["call printf('%d%2$*1$d', 1, 3)"], "E1400:")
+  call CheckLegacyAndVim9Failure(["call printf('%2$.*1$d%d', 1, 3)"], "E1400:")
+  call CheckLegacyAndVim9Failure(["call printf('%d%2$.*1$d', 1, 3)"], "E1400:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$%')"], "E1400:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$')"], "E1400:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$_')"], "E1400:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$*3$.*d', 3)"], "E1400:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$*.*2$d', 3)"], "E1400:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$*.*d', 3)"], "E1400:")
+  call CheckLegacyAndVim9Failure(["call printf('%*.*1$d', 3)"], "E1400:")
+  call CheckLegacyAndVim9Failure(["call printf('%*1$.*d', 3)"], "E1400:")
+  call CheckLegacyAndVim9Failure(["call printf('%*1$.*1$d', 3)"], "E1400:")
+
+  call CheckLegacyAndVim9Failure(["call printf('%2$d', 3, 3)"], "E1401:")
+
+  call CheckLegacyAndVim9Failure(["call printf('%2$*1$d %1$ld', 3, 3)"], "E1402:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$s %1$*1$d', 3)"], "E1402:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$p %1$*1$d', 3)"], "E1402:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$f %1$*1$d', 3)"], "E1402:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$lud %1$*1$d', 3)"], "E1402:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$llud %1$*1$d', 3)"], "E1402:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$lld %1$*1$d', 3)"], "E1402:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$s %1$*1$d', 3)"], "E1402:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$c %1$*1$d', 3)"], "E1402:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$ld %1$*1$d', 3)"], "E1402:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$ld %2$*1$d', 3, 3)"], "E1402:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$*1$ld', 3)"], "E1402:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$*1$.*1$ld', 3)"], "E1402:")
+
+  call CheckLegacyAndVim9Failure(["call printf('%1$d%2$d', 3)"], "E1403:")
+
+  call CheckLegacyAndVim9Failure(["call printf('%1$d %1$s', 3)"], "E1404:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$ld %1$s', 3)"], "E1404:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$ud %1$d', 3)"], "E1404:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$s %1$f', 3.0)"], "E1404:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$*1$d %1$ld', 3)"], "E1404:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$s %1$d', 3)"], "E1404:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$p %1$d', 3)"], "E1404:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$f %1$d', 3)"], "E1404:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$lud %1$d', 3)"], "E1404:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$llud %1$d', 3)"], "E1404:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$lld %1$d', 3)"], "E1404:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$s %1$d', 3)"], "E1404:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$c %1$d', 3)"], "E1404:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$ld %1$d', 3)"], "E1404:")
+
+  call CheckLegacyAndVim9Failure(["call printf('%1$.2$d', 3)"], "E1405:")
+  call CheckLegacyAndVim9Failure(["call printf('%01$d', 3)"], "E1405:")
+  call CheckLegacyAndVim9Failure(["call printf('%01$0d', 3)"], "E1405:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$*2d', 3)"], "E1405:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$*3.*2$d', 3)"], "E1405:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$*3$.2$d', 3)"], "E1405:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$*3$.*2d', 3)"], "E1405:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$1$.5d', 5)"], "E1405:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$5.1$d', 5)"], "E1405:")
+  call CheckLegacyAndVim9Failure(["call printf('%1$1$.1$d', 5)"], "E1405:")
+endfunc
+
+func Test_printf_pos_float()
+  let lines =<< trim END
+      call assert_equal('1.000000', printf('%1$f', 1))
+      call assert_equal('1.230000', printf('%1$f', 1.23))
+      call assert_equal('1.230000', printf('%1$F', 1.23))
+      call assert_equal('9999999.9', printf('%1$g', 9999999.9))
+      call assert_equal('9999999.9', printf('%1$G', 9999999.9))
+      call assert_equal('1.230000e+00', printf('%1$e', 1.23))
+      call assert_equal('1.230000E+00', printf('%1$E', 1.23))
+      call assert_equal('1.200000e-02', printf('%1$e', 0.012))
+      call assert_equal('-1.200000e-02', printf('%1$e', -0.012))
+      call assert_equal('0.33', printf('%1$.2f', 1.0 / 3.0))
+
+      #" When precision is 0, the dot should be omitted.
+      call assert_equal('  2', printf('%1$*2$.f', 7.0 / 3.0, 3))
+      call assert_equal('  2', printf('%2$*1$.f', 3, 7.0 / 3.0))
+      call assert_equal('  2', printf('%1$*2$.g', 7.0 / 3.0, 3))
+      call assert_equal('  2', printf('%2$*1$.g', 3, 7.0 / 3.0))
+      call assert_equal('  2e+00', printf('%1$*2$.e', 7.0 / 3.0, 7))
+      call assert_equal('  2e+00', printf('%2$*1$.e', 7, 7.0 / 3.0))
+
+      #" Float zero can be signed.
+      call assert_equal('+0.000000', printf('%1$+f', 0.0))
+      call assert_equal('0.000000', printf('%1$f', 1.0 / (1.0 / 0.0)))
+      call assert_equal('-0.000000', printf('%1$f', 1.0 / (-1.0 / 0.0)))
+      call assert_equal('0.0', printf('%1$s', 1.0 / (1.0 / 0.0)))
+      call assert_equal('-0.0', printf('%1$s', 1.0 / (-1.0 / 0.0)))
+      call assert_equal('0.0', printf('%1$S', 1.0 / (1.0 / 0.0)))
+      call assert_equal('-0.0', printf('%1$S', 1.0 / (-1.0 / 0.0)))
+
+      #" Float infinity can be signed.
+      call assert_equal('inf', printf('%1$f', 1.0 / 0.0))
+      call assert_equal('-inf', printf('%1$f', -1.0 / 0.0))
+      call assert_equal('inf', printf('%1$g', 1.0 / 0.0))
+      call assert_equal('-inf', printf('%1$g', -1.0 / 0.0))
+      call assert_equal('inf', printf('%1$e', 1.0 / 0.0))
+      call assert_equal('-inf', printf('%1$e', -1.0 / 0.0))
+      call assert_equal('INF', printf('%1$F', 1.0 / 0.0))
+      call assert_equal('-INF', printf('%1$F', -1.0 / 0.0))
+      call assert_equal('INF', printf('%1$E', 1.0 / 0.0))
+      call assert_equal('-INF', printf('%1$E', -1.0 / 0.0))
+      call assert_equal('INF', printf('%1$E', 1.0 / 0.0))
+      call assert_equal('-INF', printf('%1$G', -1.0 / 0.0))
+      call assert_equal('+inf', printf('%1$+f', 1.0 / 0.0))
+      call assert_equal('-inf', printf('%1$+f', -1.0 / 0.0))
+      call assert_equal(' inf', printf('%1$ f',  1.0 / 0.0))
+      call assert_equal('   inf', printf('%1$*2$f', 1.0 / 0.0, 6))
+      call assert_equal('  -inf', printf('%1$*2$f', -1.0 / 0.0, 6))
+      call assert_equal('   inf', printf('%1$*2$g', 1.0 / 0.0, 6))
+      call assert_equal('  -inf', printf('%1$*2$g', -1.0 / 0.0, 6))
+      call assert_equal('  +inf', printf('%1$+*2$f', 1.0 / 0.0, 6))
+      call assert_equal('   inf', printf('%1$ *2$f', 1.0 / 0.0, 6))
+      call assert_equal('  +inf', printf('%1$+0*2$f', 1.0 / 0.0, 6))
+      call assert_equal('inf   ', printf('%1$-*2$f', 1.0 / 0.0, 6))
+      call assert_equal('-inf  ', printf('%1$-*2$f', -1.0 / 0.0, 6))
+      call assert_equal('+inf  ', printf('%1$-+*2$f', 1.0 / 0.0, 6))
+      call assert_equal(' inf  ', printf('%1$- *2$f', 1.0 / 0.0, 6))
+      call assert_equal('-INF  ', printf('%1$-*2$F', -1.0 / 0.0, 6))
+      call assert_equal('+INF  ', printf('%1$-+*2$F', 1.0 / 0.0, 6))
+      call assert_equal(' INF  ', printf('%1$- *2$F', 1.0 / 0.0, 6))
+      call assert_equal('INF   ', printf('%1$-*2$G', 1.0 / 0.0, 6))
+      call assert_equal('-INF  ', printf('%1$-*2$G', -1.0 / 0.0, 6))
+      call assert_equal('INF   ', printf('%1$-*2$E', 1.0 / 0.0, 6))
+      call assert_equal('-INF  ', printf('%1$-*2$E', -1.0 / 0.0, 6))
+      call assert_equal('   inf', printf('%2$*1$f', 6, 1.0 / 0.0))
+      call assert_equal('  -inf', printf('%2$*1$f', 6, -1.0 / 0.0))
+      call assert_equal('   inf', printf('%2$*1$g', 6, 1.0 / 0.0))
+      call assert_equal('  -inf', printf('%2$*1$g', 6, -1.0 / 0.0))
+      call assert_equal('  +inf', printf('%2$+*1$f', 6, 1.0 / 0.0))
+      call assert_equal('   inf', printf('%2$ *1$f', 6, 1.0 / 0.0))
+      call assert_equal('  +inf', printf('%2$+0*1$f', 6, 1.0 / 0.0))
+      call assert_equal('inf   ', printf('%2$-*1$f', 6, 1.0 / 0.0))
+      call assert_equal('-inf  ', printf('%2$-*1$f', 6, -1.0 / 0.0))
+      call assert_equal('+inf  ', printf('%2$-+*1$f', 6, 1.0 / 0.0))
+      call assert_equal(' inf  ', printf('%2$- *1$f', 6, 1.0 / 0.0))
+      call assert_equal('-INF  ', printf('%2$-*1$F', 6, -1.0 / 0.0))
+      call assert_equal('+INF  ', printf('%2$-+*1$F', 6, 1.0 / 0.0))
+      call assert_equal(' INF  ', printf('%2$- *1$F', 6, 1.0 / 0.0))
+      call assert_equal('INF   ', printf('%2$-*1$G', 6, 1.0 / 0.0))
+      call assert_equal('-INF  ', printf('%2$-*1$G', 6, -1.0 / 0.0))
+      call assert_equal('INF   ', printf('%2$-*1$E', 6, 1.0 / 0.0))
+      call assert_equal('-INF  ', printf('%2$-*1$E', 6, -1.0 / 0.0))
+      call assert_equal("str2float('inf')", printf('%1$s', 1.0 / 0.0))
+      call assert_equal("-str2float('inf')", printf('%1$s', -1.0 / 0.0))
+
+      #" Test special case where max precision is truncated at 340.
+      call assert_equal('1.000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000', printf('%1$.*2$f', 1.0, 330))
+      call assert_equal('1.000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000', printf('%2$.*1$f', 330, 1.0))
+      call assert_equal('1.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000', printf('%1$.*2$f', 1.0, 340))
+      call assert_equal('1.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000', printf('%2$.*1$f', 340, 1.0))
+      call assert_equal('1.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000', printf('%1$.*2$f', 1.0, 350))
+      call assert_equal('1.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000', printf('%2$.*1$f', 350, 1.0))
+
+      #" Float nan (not a number) has no sign.
+      call assert_equal('nan', printf('%1$f', sqrt(-1.0)))
+      call assert_equal('nan', printf('%1$f', 0.0 / 0.0))
+      call assert_equal('nan', printf('%1$f', -0.0 / 0.0))
+      call assert_equal('nan', printf('%1$g', 0.0 / 0.0))
+      call assert_equal('nan', printf('%1$e', 0.0 / 0.0))
+      call assert_equal('NAN', printf('%1$F', 0.0 / 0.0))
+      call assert_equal('NAN', printf('%1$G', 0.0 / 0.0))
+      call assert_equal('NAN', printf('%1$E', 0.0 / 0.0))
+      call assert_equal('NAN', printf('%1$F', -0.0 / 0.0))
+      call assert_equal('NAN', printf('%1$G', -0.0 / 0.0))
+      call assert_equal('NAN', printf('%1$E', -0.0 / 0.0))
+      call assert_equal('   nan', printf('%1$*2$f', 0.0 / 0.0, 6))
+      call assert_equal('   nan', printf('%1$0*2$f', 0.0 / 0.0, 6))
+      call assert_equal('nan   ', printf('%1$-*2$f', 0.0 / 0.0, 6))
+      call assert_equal('nan   ', printf('%1$- *2$f', 0.0 / 0.0, 6))
+      call assert_equal('   nan', printf('%2$*1$f', 6, 0.0 / 0.0))
+      call assert_equal('   nan', printf('%2$0*1$f', 6, 0.0 / 0.0))
+      call assert_equal('nan   ', printf('%2$-*1$f', 6, 0.0 / 0.0))
+      call assert_equal('nan   ', printf('%2$- *1$f', 6, 0.0 / 0.0))
+      call assert_equal("str2float('nan')", printf('%1$s', 0.0 / 0.0))
+      call assert_equal("str2float('nan')", printf('%1$s', -0.0 / 0.0))
+      call assert_equal("str2float('nan')", printf('%1$S', 0.0 / 0.0))
+      call assert_equal("str2float('nan')", printf('%1$S', -0.0 / 0.0))
+  END
+  call CheckLegacyAndVim9Success(lines)
+
+  call CheckLegacyAndVim9Failure(['echo printf("%f", "a")'], 'E807:')
+endfunc
+
+func Test_printf_pos_errors()
+  call CheckLegacyAndVim9Failure(['echo printf("%1$d", {})'], 'E728:')
+  call CheckLegacyAndVim9Failure(['echo printf("%1$d", [])'], 'E745:')
+  call CheckLegacyAndVim9Failure(['echo printf("%1$d", 1, 2)'], 'E767:')
+  call CheckLegacyAndVim9Failure(['echo printf("%*d", 1)'], 'E766:')
+  call CheckLegacyAndVim9Failure(['echo printf("%1$s")'], 'E1403:')
+  call CheckLegacyAndVim9Failure(['echo printf("%1$d", 1.2)'], 'E805:')
+  call CheckLegacyAndVim9Failure(['echo printf("%1$f")'], 'E1403:')
+endfunc
+
+func Test_printf_pos_64bit()
+  let lines =<< trim END
+      call assert_equal("123456789012345", printf('%1$d', 123456789012345))
+  END
+  call CheckLegacyAndVim9Success(lines)
+endfunc
+
+func Test_printf_pos_spec_s()
+  let lines =<< trim END
+      #" number
+      call assert_equal("1234567890", printf('%1$s', 1234567890))
+
+      #" string
+      call assert_equal("abcdefgi", printf('%1$s', "abcdefgi"))
+
+      #" float
+      call assert_equal("1.23", printf('%1$s', 1.23))
+
+      #" list
+      VAR lvalue = [1, 'two', ['three', 4]]
+      call assert_equal(string(lvalue), printf('%1$s', lvalue))
+
+      #" dict
+      VAR dvalue = {'key1': 'value1', 'key2': ['list', 'lvalue'], 'key3': {'dict': 'lvalue'}}
+      call assert_equal(string(dvalue), printf('%1$s', dvalue))
+
+      #" funcref
+      call assert_equal('printf', printf('%1$s', 'printf'->function()))
+
+      #" partial
+      call assert_equal(string(function('printf', ['%1$s'])), printf('%1$s', function('printf', ['%1$s'])))
+  END
+  call CheckLegacyAndVim9Success(lines)
+endfunc
+
+func Test_printf_pos_spec_b()
+  let lines =<< trim END
+      call assert_equal("0", printf('%1$b', 0))
+      call assert_equal("00001100", printf('%1$0*2$b', 12, 8))
+      call assert_equal("11111111", printf('%1$0*2$b', 0xff, 8))
+      call assert_equal("   1111011", printf('%1$*2$b', 123, 10))
+      call assert_equal("0001111011", printf('%1$0*2$b', 123, 10))
+      call assert_equal(" 0b1111011", printf('%1$#*2$b', 123, 10))
+      call assert_equal("0B01111011", printf('%1$#0*2$B', 123, 10))
+      call assert_equal("00001100", printf('%2$0*1$b', 8, 12))
+      call assert_equal("11111111", printf('%2$0*1$b', 8, 0xff))
+      call assert_equal("   1111011", printf('%2$*1$b', 10, 123))
+      call assert_equal("0001111011", printf('%2$0*1$b', 10, 123))
+      call assert_equal(" 0b1111011", printf('%2$#*1$b', 10, 123))
+      call assert_equal("0B01111011", printf('%2$#0*1$B', 10, 123))
+      call assert_equal("1001001100101100000001011010010", printf('%1$b', 1234567890))
+      call assert_equal("11100000100100010000110000011011101111101111001", printf('%1$b', 123456789012345))
+      call assert_equal("1111111111111111111111111111111111111111111111111111111111111111", printf('%1$b', -1))
+  END
+  call CheckLegacyAndVim9Success(lines)
+endfunc
+
+" vim: shiftwidth=2 sts=2 expandtab
diff --git a/test/unit/eval/typval_spec.lua b/test/unit/eval/typval_spec.lua
index a60700287f..6fb8ba5a1c 100644
--- a/test/unit/eval/typval_spec.lua
+++ b/test/unit/eval/typval_spec.lua
@@ -1439,7 +1439,7 @@ describe('typval.c', function()
           eq('3', tv_list_find_str(l, 2))
           eq('3', tv_list_find_str(l, -3))
 
-          alloc_log:check({a.freed(alloc_log.null)})
+          alloc_log:check({a.freed(alloc_log.null), a.freed(alloc_log.null)})
         end)
         itp('returns string when used with VAR_STRING items', function()
           local l = list('1', '2', '3', '4', '5')
@@ -1768,7 +1768,7 @@ describe('typval.c', function()
           local s44 = check_emsg(function() return lib.tv_dict_get_string(d, 't', false) end,
                                  nil)
           eq('44.0', ffi.string(s44))
-          alloc_log:check({a.freed(alloc_log.null)})
+          alloc_log:check({a.freed(alloc_log.null), a.freed(alloc_log.null)})
         end)
         itp('allocates a string copy when requested', function()
           local function tv_dict_get_string_alloc(d, key, emsg, is_float)
@@ -1779,7 +1779,7 @@ describe('typval.c', function()
             if not emsg then
               if s_ret then
                 if is_float then
-                  alloc_log:check({a.freed(alloc_log.null), a.str(ret, s_ret)})
+                  alloc_log:check({a.freed(alloc_log.null), a.freed(alloc_log.null), a.str(ret, s_ret)})
                 else
                   alloc_log:check({a.str(ret, s_ret)})
                 end
@@ -1810,7 +1810,7 @@ describe('typval.c', function()
           local s_ret = (ret ~= nil) and ffi.string(ret) or nil
           if not emsg then
             if is_float then
-              alloc_log:check({a.freed(alloc_log.null)})
+              alloc_log:check({a.freed(alloc_log.null), a.freed(alloc_log.null)})
             else
               alloc_log:check({})
             end
@@ -1856,7 +1856,7 @@ describe('typval.c', function()
           local s_ret = (ret ~= nil) and ffi.string(ret) or nil
           if not emsg then
             if is_float then
-              alloc_log:check({a.freed(alloc_log.null)})
+              alloc_log:check({a.freed(alloc_log.null), a.freed(alloc_log.null)})
             else
               alloc_log:check({})
             end
@@ -3018,7 +3018,7 @@ describe('typval.c', function()
           if emsg then
             alloc_log:clear()
           elseif tv.v_type == lib.VAR_FLOAT then
-            alloc_log:check({a.freed(alloc_log.null)})
+            alloc_log:check({a.freed(alloc_log.null), a.freed(alloc_log.null)})
           else
             alloc_log:check({})
           end
diff --git a/test/unit/strings_spec.lua b/test/unit/strings_spec.lua
index bb5ea12edc..68790ea026 100644
--- a/test/unit/strings_spec.lua
+++ b/test/unit/strings_spec.lua
@@ -140,37 +140,83 @@ describe('vim_strchr()', function()
 end)
 
 describe('vim_snprintf()', function()
-  itp('truncation', function()
-    local function check(expected, buf, bsize, fmt, ...)
-      eq(#expected, strings.vim_snprintf(buf, bsize, fmt, ...))
-      if bsize > 0 then
-        local actual = ffi.string(buf, math.min(#expected + 1, bsize))
-        eq(expected:sub(1, bsize - 1) .. '\0', actual)
-      end
+  local function a(expected, buf, bsize, fmt, ...)
+    eq(#expected, strings.vim_snprintf(buf, bsize, fmt, ...))
+    if bsize > 0 then
+      local actual = ffi.string(buf, math.min(#expected + 1, bsize))
+      eq(expected:sub(1, bsize - 1) .. '\0', actual)
     end
+  end
 
+  local function i(n) return ffi.cast('int', n) end
+  local function l(n) return ffi.cast('long', n) end
+  local function u(n) return ffi.cast('unsigned', n) end
+  local function ll(n) return ffi.cast('long long', n) end
+  local function ul(n) return ffi.cast('unsigned long', n) end
+  local function ull(n) return ffi.cast('unsigned long long', n) end
+
+  itp('truncation', function()
     for bsize = 0, 14 do
       local buf = ffi.gc(strings.xmalloc(bsize), strings.xfree)
-      check('1234567', buf, bsize, '%d', ffi.cast('int', 1234567))
-      check('1234567', buf, bsize, '%ld', ffi.cast('long', 1234567))
-      check('  1234567', buf, bsize, '%9ld', ffi.cast('long', 1234567))
-      check('1234567  ', buf, bsize, '%-9ld', ffi.cast('long', 1234567))
-      check('deadbeef', buf, bsize, '%x', ffi.cast('unsigned', 0xdeadbeef))
-      check('001100', buf, bsize, '%06b', ffi.cast('int', 12))
-      check('1.234000', buf, bsize, '%f', ffi.cast('double', 1.234))
-      check('1.234000e+00', buf, bsize, '%e', ffi.cast('double', 1.234))
-      check('nan', buf, bsize, '%f', ffi.cast('double', 0.0 / 0.0))
-      check('inf', buf, bsize, '%f', ffi.cast('double', 1.0 / 0.0))
-      check('-inf', buf, bsize, '%f', ffi.cast('double', -1.0 / 0.0))
-      check('-0.000000', buf, bsize, '%f', ffi.cast('double', -0.0))
-      check('漢語', buf, bsize, '%s', '漢語')
-      check('  漢語', buf, bsize, '%8s', '漢語')
-      check('漢語  ', buf, bsize, '%-8s', '漢語')
-      check('漢', buf, bsize, '%.3s', '漢語')
-      check('  foo', buf, bsize, '%5S', 'foo')
-      check('%%%', buf, bsize, '%%%%%%')
-      check('0x87654321', buf, bsize, '%p', ffi.cast('char *', 0x87654321))
-      check('0x0087654321', buf, bsize, '%012p', ffi.cast('char *', 0x87654321))
+      a('1.00000001e7', buf, bsize, '%.8g', 10000000.1)
+      a('1234567', buf, bsize, '%d', i(1234567))
+      a('1234567', buf, bsize, '%ld', l(1234567))
+      a('  1234567', buf, bsize, '%9ld', l(1234567))
+      a('1234567  ', buf, bsize, '%-9ld', l(1234567))
+      a('deadbeef', buf, bsize, '%x', u(0xdeadbeef))
+      a('001100', buf, bsize, '%06b', u(12))
+      a('one two', buf, bsize, '%s %s', 'one', 'two')
+      a('1.234000', buf, bsize, '%f', 1.234)
+      a('1.234000e+00', buf, bsize, '%e', 1.234)
+      a('nan', buf, bsize, '%f', 0.0 / 0.0)
+      a('inf', buf, bsize, '%f', 1.0 / 0.0)
+      a('-inf', buf, bsize, '%f', -1.0 / 0.0)
+      a('-0.000000', buf, bsize, '%f', -0.0)
+      a('漢語', buf, bsize, '%s', '漢語')
+      a('  漢語', buf, bsize, '%8s', '漢語')
+      a('漢語  ', buf, bsize, '%-8s', '漢語')
+      a('漢', buf, bsize, '%.3s', '漢語')
+      a('  foo', buf, bsize, '%5S', 'foo')
+      a('%%%', buf, bsize, '%%%%%%')
+      a('0x87654321', buf, bsize, '%p', ffi.cast('char *', 0x87654321))
+      a('0x0087654321', buf, bsize, '%012p', ffi.cast('char *', 0x87654321))
+    end
+  end)
+
+  itp('positional arguments', function()
+    for bsize = 0, 24 do
+      local buf = ffi.gc(strings.xmalloc(bsize), strings.xfree)
+      a('1234567  ', buf, bsize, '%1$*2$ld', l(1234567), i(-9))
+      a('1234567  ', buf, bsize, '%1$*2$.*3$ld', l(1234567), i(-9), i(5))
+      a('1234567  ', buf, bsize, '%1$*3$.*2$ld', l(1234567), i(5), i(-9))
+      a('1234567  ', buf, bsize, '%3$*1$.*2$ld', i(-9), i(5), l(1234567))
+      a('1234567', buf, bsize, '%1$ld', l(1234567))
+      a('  1234567', buf, bsize, '%1$*2$ld', l(1234567), i(9))
+      a('9 12345 7654321', buf, bsize, '%2$ld %1$d %3$lu', i(12345), l(9), ul(7654321))
+      a('9 1234567 7654321', buf, bsize, '%2$d %1$ld %3$lu', l(1234567), i(9), ul(7654321))
+      a('9 1234567 7654321', buf, bsize, '%2$d %1$lld %3$lu', ll(1234567), i(9), ul(7654321))
+      a('9 12345 7654321', buf, bsize, '%2$ld %1$u %3$lu', u(12345), l(9), ul(7654321))
+      a('9 1234567 7654321', buf, bsize, '%2$d %1$lu %3$lu', ul(1234567), i(9), ul(7654321))
+      a('9 1234567 7654321', buf, bsize, '%2$d %1$llu %3$lu', ull(1234567), i(9), ul(7654321))
+      a('9 1234567 7654321', buf, bsize, '%2$d %1$llu %3$lu', ull(1234567), i(9), ul(7654321))
+      a('9 deadbeef 7654321', buf, bsize, '%2$d %1$x %3$lu', u(0xdeadbeef), i(9), ul(7654321))
+      a('9 c 7654321', buf, bsize, '%2$ld %1$c %3$lu', i(('c'):byte()), l(9), ul(7654321))
+      a('9 hi 7654321', buf, bsize, '%2$ld %1$s %3$lu', 'hi', l(9), ul(7654321))
+      a('9 0.000000e+00 7654321', buf, bsize, '%2$ld %1$e %3$lu', 0.0, l(9), ul(7654321))
+      a('two one two', buf, bsize, '%2$s %1$s %2$s', 'one', 'two', 'three')
+      a('three one two', buf, bsize, '%3$s %1$s %2$s', 'one', 'two', 'three')
+      a('1234567', buf, bsize, '%1$d', i(1234567))
+      a('deadbeef', buf, bsize, '%1$x', u(0xdeadbeef))
+      a('001100', buf, bsize, '%1$0.*2$b', u(12), i(6))
+      a('one two', buf, bsize, '%1$s %2$s', 'one', 'two')
+      a('001100', buf, bsize, '%06b', u(12))
+      a('two one', buf, bsize, '%2$s %1$s', 'one', 'two')
+      a('1.234000', buf, bsize, '%1$f', 1.234)
+      a('1.234000e+00', buf, bsize, '%1$e', 1.234)
+      a('nan', buf, bsize, '%1$f', 0.0 / 0.0)
+      a('inf', buf, bsize, '%1$f', 1.0 / 0.0)
+      a('-inf', buf, bsize, '%1$f', -1.0 / 0.0)
+      a('-0.000000', buf, bsize, '%1$f', -0.0)
     end
   end)
 end)