fix: std.format rejects boolean for numeric conversion codes#1016
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He-Pin wants to merge 2 commits into
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fix: std.format rejects boolean for numeric conversion codes#1016He-Pin wants to merge 2 commits into
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Motivation: sjsonnet silently coerced booleans to integers for numeric format codes (%d, %f, %e, %x, %o, %g etc.), treating true as 1 and false as 0. Both C++ jsonnet and jrsonnet correctly reject this with a type error. This is a permissiveness bug that can mask logic errors in Jsonnet programs. Modification: - Format.scala: Restrict Val.True/Val.False match arms to only allow %s conversion. All numeric conversion codes (%d, %i, %u, %o, %x, %X, %e, %E, %f, %F, %g, %G) now produce "expected number or string, got boolean". - Added error tests for %d and %f with boolean values. Result: "%d" % true now errors instead of silently returning "1". Cross-implementation comparison: | Expression | C++ jsonnet | go-jsonnet | jrsonnet | sjsonnet (before) | sjsonnet (after) | |-----------------|---------------------|------------|-----------------------|--------------------|------------------| | "%d" % true | ERROR: got boolean | ERROR | ERROR: got boolean | "1" ❌ | ERROR ✅ | | "%f" % false | ERROR | ERROR | ERROR | "0.000000" ❌ | ERROR ✅ | | "%x" % true | ERROR | ERROR | ERROR | "1" ❌ | ERROR ✅ | | "%e" % true | ERROR | ERROR | ERROR | "1.000000e+00" ❌ | ERROR ✅ | | "%s" % true | "true" | "true" | "true" | "true" ✅ | "true" ✅ |
He-Pin
commented
Jun 24, 2026
| case 'E' => formatExponent(formatted, b) | ||
| case 'f' | 'F' => formatFloat(formatted, b) | ||
| case 'g' => formatGeneric(formatted, b).toLowerCase | ||
| case 'G' => formatGeneric(formatted, b) |
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Summary
std.formatwas silently coercing booleans to integers for all numeric format codes (%d,%f,%e,%x,%o,%getc.), treatingtrueas1andfalseas0. C++ jsonnet, go-jsonnet, and jrsonnet all correctly reject this with a type error.Restricted
Val.True/Val.Falseto only allow%sconversion. All numeric codes now produce"expected number or string, got boolean".Cross-implementation comparison
"%d" % true"1"❌"%d" % false"0"❌"%f" % true"1.000000"❌"%f" % false"0.000000"❌"%e" % true"1.000000e+00"❌"%x" % true"1"❌"%o" % true"1"❌"%g" % true"1"❌"%s" % true"true""true""true""true"✅"true"✅"%s" % false"false""false""false""false"✅"false"✅Test plan
./mill sjsonnet.jvm[3.3.7].test— all suites greenerror.format_d_boolean.jsonnet,error.format_f_boolean.jsonnet