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https://issues.apache.org/jira/browse/GROOVY-12692?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18138375#comment-18138375
]
ASF GitHub Bot commented on GROOVY-12692:
-----------------------------------------
codeconsole opened a new pull request, #3213:
URL: https://github.com/apache/groovy/pull/3213
JIRA: [GROOVY-12692](https://issues.apache.org/jira/browse/GROOVY-12692)
### The bug
With `groovy.typecheckers.FormatStringChecker` enabled, a format call whose
arguments are not all constants is checked as if `%%` and `%n` each took an
argument. A valid call is rejected:
```groovy
import groovy.transform.TypeChecked
@TypeChecked(extensions = 'groovy.typecheckers.FormatStringChecker')
String show(String s) {
String.format('100%% %s', s)
}
```
```text
[Static type checking] - MissingFormatArgument: Format specifier '%s'
```
`java.util.Formatter` gives `%%` and `%n` no argument, so the call returns
`100% done` for `s = 'done'`. With a constant argument the checker accepts the
same format string. On the same path:
| call | `java.util.Formatter` | checker before |
| -
> FormatStringChecker counts %% and %n as taking an argument when the arguments
> are not constants
> -----------------------------------------------------------------------------------------------
>
> Key: GROOVY-12692
> URL: https://issues.apache.org/jira/browse/GROOVY-12692
> Project: Groovy
> Issue Type: Bug
> Affects Versions: 6.0.0
> Reporter: Scott Murphy Heiberg
> Priority: Major
>
> With {{groovy.typecheckers.FormatStringChecker}} enabled, a format call whose
> arguments are not all constants is checked as if {{%%}} and {{%n}} each took
> an argument. A valid call is rejected.
> {{Percent.groovy}}:
> {code:groovy}
> import groovy.transform.TypeChecked
> @TypeChecked(extensions = 'groovy.typecheckers.FormatStringChecker')
> String show(String s) {
> String.format('100%% %s', s)
> }
> assert show('done') == '100% done'
> {code}
> {code:sh}
> groovyc Percent.groovy
> {code}
> Actual: exit 1 and
> {code:text}
> org.codehaus.groovy.control.MultipleCompilationErrorsException: startup
> failed:
> Percent.groovy: 5: [Static type checking] - MissingFormatArgument: Format
> specifier '%s'
> @ line 5, column 5.
> String.format('100%% %s', s)
> ^
> 1 error
> {code}
> Expected: the source compiles. {{java.util.Formatter}} gives {{%%}} and
> {{%n}} no argument, so the call returns {{100% done}}. The checker accepts
> the same format string when the argument is a constant
> ({{String.format('100%% %s', 'done')}}).
> More calls, each in a method with a {{String s}} parameter, with {{s =
> 'done'}} at run time:
> ||call||java.util.Formatter||FormatStringChecker||
> |{{String.format('%s%n', s)}}|returns {{done}} and a line
> separator|MissingFormatArgument: Format specifier '%n'|
> |{{String.format('%n%s', s)}}|returns a line separator and
> {{done}}|MissingFormatArgument: Format specifier '%s'|
> |{{String.format('%s %%', s)}}|returns {{done %}}|MissingFormatArgument:
> Format specifier '%%'|
> |{{String.format('%s %% %s', s, s)}}|returns {{done %
> done}}|MissingFormatArgument: Format specifier '%s'|
> |{{String.format('%s %% %<s', s)}}|returns {{done %
> done}}|MissingFormatArgument: Format specifier '%%'|
> |{{String.format('100%% %d', s)}}|IllegalFormatConversionException: d !=
> java.lang.String|MissingFormatArgument: Format specifier '%d'|
> |{{String.format('%% %<s', s)}}|MissingFormatArgumentException: Format
> specifier '%<s'|no error|
> |{{sprintf('%s%n', s)}}|returns {{done}} and a line
> separator|MissingFormatArgument: Format specifier '%n'|
> The rows for {{'100%% %d'}} and {{'%% %<s'}} show the other side of the same
> mistake: because the {{%%}} is given an argument, a real error is reported as
> a different error, or not at all.
> Affected versions: 6.0.0, 6.0.0-beta-1, 5.0.8 and 5.0.0 reject
> {{Percent.groovy}} the same way, and so does current master (7.0.0-SNAPSHOT
> at 5e9212ce1e).
> Cause: when not all arguments are constants, {{checkFormatStringTypes}}
> handles every specifier the format pattern matches as one that takes an
> argument: it checks the index against the number of arguments, reads that
> argument's type, and advances both the next index and the previous argument
> that {{%<}} refers to. The {{switch}} that follows skips {{%}} and {{n}}, but
> only after this bookkeeping. With constant arguments the checker runs
> {{java.util.Formatter}} itself, which is why that path is right.
> Fix outline: handle {{%%}} and {{%n}} before the argument bookkeeping,
> keeping the duplicate-flag check they already get.
> A pull request with regression tests follows.
> Environment: Groovy 6.0.0 on BellSoft JDK 21.0.12, macOS 26.5 (arm64);
> reproduced on master at 5e9212ce1e with the same JDK.
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