fix: format + flag now correctly overrides space flag - #1089
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stephenamar-db merged 1 commit intoJul 28, 2026
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Motivation:
When both + and space flags are present in std.format (e.g. "%+ d"),
the + flag must override the space flag per Python/C printf semantics.
sjsonnet had the condition order reversed, causing space to win.
Modification:
Swap the condition order in Format.scala so signCharacter (+) is
checked before blankBeforePositive (space).
Result:
std.format("%+ d", [42]) now produces "+42" instead of " 42",
matching go-jsonnet, jrsonnet, Python, and C99 §7.19.6.1.
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Summary
+and space flags appear instd.format(e.g."%+ d"), the+flag must override the space flag. sjsonnet had the condition order reversed, causing space to win.Behavior comparison
std.format("%+ d", [42])" 42"❌"+42"✅"+42""+42"'+42'std.format("% +d", [42])" 42"❌"+42"✅"+42""+42"'+42'std.format("%+ f", [3.14])" 3.140000"❌"+3.140000"✅"+3.140000""+3.140000"'+3.140000'std.format("%+ d", [0])" 0"❌"+0"✅"+0""+0"'+0'std.format("% d", [42])" 42"✅" 42"✅" 42"" 42"' 42'std.format("%+d", [42])"+42"✅"+42"✅"+42""+42"'+42'std.format("%+ d", [-42])"-42"✅"-42"✅"-42""-42"'-42'Specification reference
+and space flags both appear, the space flag is ignored."%formatting:'%+ d' % 42→'+42'%"Test plan
./mill 'sjsonnet.jvm[2.13.18]'.test— all tests pass, no regressions