Fix duplicate config section when writing a second key#314
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semver: patch
docs: skip
setInFile() appended a new [section] header whenever the target field was absent. Writing a second distinct key to a section that already existed (e.g. a second [cli] field) therefore produced a duplicate TOML table. TOML forbids duplicate tables, so the next config load failed with "table cli already exists", corrupting the user's config. Insert the field under the existing section header when that section is already present; only append a new header when the section is absent. Add a regression test covering a second key in an existing section.
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Summary
config.Setpersists individual keys toconfig.tomlthroughsetInFile, which edits the file surgically to preserve user comments and formatting. It had a latent corruption bug: when the target field was absent, it always appended a brand-new[section]header — even when that section already existed. Writing a second, distinct key to an existing section produced a duplicate TOML table, which the parser rejects, so every subsequent config load failed.On a field-match miss,
setInFileunconditionally appended a new section:Today only
cli.update_skipped_versionis ever written, so the duplicate-header path is never hit — the bug is latent. But as soon as a second[cli]key is introduced (e.g. an update-notification cadence setting), the sequence becomes:cli.update_skipped_version→ appends[cli](first time, fine).cli.notify_cadence→ field absent → appends a second[cli]header.viper.ReadInConfig/toml.Unmarshalfails withtoml: table cli already exists.The user's
config.tomlis now unparseable and every command fails until the file is hand-repaired.Before (corrupted output):
After (fixed):
When the field is absent but the
[section]header already exists, insert the new field under the existing header instead of appending a duplicate table. A fresh[section]is appended only when the section does not yet exist. Behavior for existing single-field configs is unchanged; only the previously-broken "second field in an existing section" path differs.