$ cat >> $HGRCPATH << EOF

  > [extensions]

  > share =

  > EOF

store and revlogv1 are required in source

  $ hg --config format.usestore=false init no-store

  $ hg -R no-store debugupgraderepo

  abort: cannot upgrade repository; requirement missing: store

  [255]

  $ hg init no-revlogv1

  $ cat > no-revlogv1/.hg/requires << EOF

  > dotencode

  > fncache

  > generaldelta

  > store

  > EOF

  $ hg -R no-revlogv1 debugupgraderepo

  abort: cannot upgrade repository; requirement missing: revlogv1

  [255]

Cannot upgrade shared repositories

  $ hg init share-parent

  $ hg -q share share-parent share-child

  $ hg -R share-child debugupgraderepo

  abort: cannot upgrade repository; unsupported source requirement: shared

  [255]

Do not yet support upgrading manifestv2 and treemanifest repos

  $ hg --config experimental.manifestv2=true init manifestv2

  $ hg -R manifestv2 debugupgraderepo

  abort: cannot upgrade repository; unsupported source requirement: manifestv2

  [255]

  $ hg --config experimental.treemanifest=true init treemanifest

  $ hg -R treemanifest debugupgraderepo

  abort: cannot upgrade repository; unsupported source requirement: treemanifest

  [255]

Cannot add manifestv2 or treemanifest requirement during upgrade

  $ hg init disallowaddedreq

  $ hg -R disallowaddedreq --config experimental.manifestv2=true --config experimental.treemanifest=true debugupgraderepo

  abort: cannot upgrade repository; do not support adding requirement: manifestv2, treemanifest

  [255]

An upgrade of a repository created with recommended settings only suggests optimizations

  $ hg init empty

  $ cd empty

  $ hg debugformat

  format-variant repo

  fncache:        yes

  dotencode:      yes

  generaldelta:   yes

  plain-cl-delta: yes

  compression:    zlib

  $ hg debugformat --verbose

  format-variant repo config default

  fncache:        yes    yes     yes

  dotencode:      yes    yes     yes

  generaldelta:   yes    yes     yes

  plain-cl-delta: yes    yes     yes

  compression:    zlib   zlib    zlib

  $ hg debugformat --verbose --config format.usegfncache=no

  format-variant repo config default

  fncache:        yes    yes     yes

  dotencode:      yes    yes     yes

  generaldelta:   yes    yes     yes

  plain-cl-delta: yes    yes     yes

  compression:    zlib   zlib    zlib

  $ hg debugformat --verbose --config format.usegfncache=no --color=debug

  format-variant repo config default

  [formatvariant.name.uptodate|fncache:       ][formatvariant.repo.uptodate| yes][formatvariant.config.default|    yes][formatvariant.default|     yes]

  [formatvariant.name.uptodate|dotencode:     ][formatvariant.repo.uptodate| yes][formatvariant.config.default|    yes][formatvariant.default|     yes]

  [formatvariant.name.uptodate|generaldelta:  ][formatvariant.repo.uptodate| yes][formatvariant.config.default|    yes][formatvariant.default|     yes]

  [formatvariant.name.uptodate|plain-cl-delta:][formatvariant.repo.uptodate| yes][formatvariant.config.default|    yes][formatvariant.default|     yes]

  [formatvariant.name.uptodate|compression:   ][formatvariant.repo.uptodate| zlib][formatvariant.config.default|   zlib][formatvariant.default|    zlib]

  $ hg debugupgraderepo

  (no feature deficiencies found in existing repository)

  performing an upgrade with "--run" will make the following changes:

  requirements

     preserved: dotencode, fncache, generaldelta, revlogv1, store

  additional optimizations are available by specifying "--optimize <name>":

  redeltaparent

     deltas within internal storage will be recalculated to choose an optimal base revision where this was not already done; the size of the repository may shrink and various operations may become faster; the first time this optimization is performed could slow down upgrade execution considerably; subsequent invocations should not run noticeably slower

  redeltamultibase

     deltas within internal storage will be recalculated against multiple base revision and the smallest difference will be used; the size of the repository may shrink significantly when there are many merges; this optimization will slow down execution in proportion to the number of merges in the repository and the amount of files in the repository; this slow down should not be significant unless there are tens of thousands of files and thousands of merges

  redeltaall

     deltas within internal storage will always be recalculated without reusing prior deltas; this will likely make execution run several times slower; this optimization is typically not needed

--optimize can be used to add optimizations

  $ hg debugupgrade --optimize redeltaparent

  (no feature deficiencies found in existing repository)

  performing an upgrade with "--run" will make the following changes:

  requirements

     preserved: dotencode, fncache, generaldelta, revlogv1, store

  redeltaparent

     deltas within internal storage will choose a new base revision if needed

  additional optimizations are available by specifying "--optimize <name>":

  redeltamultibase

     deltas within internal storage will be recalculated against multiple base revision and the smallest difference will be used; the size of the repository may shrink significantly when there are many merges; this optimization will slow down execution in proportion to the number of merges in the repository and the amount of files in the repository; this slow down should not be significant unless there are tens of thousands of files and thousands of merges

  redeltaall

     deltas within internal storage will always be recalculated without reusing prior deltas; this will likely make execution run several times slower; this optimization is typically not needed

Various sub-optimal detections work

  $ cat > .hg/requires << EOF

  > revlogv1

  > store

  > EOF

  $ hg debugformat

  format-variant repo

  fncache:         no

  dotencode:       no

  generaldelta:    no

  plain-cl-delta: yes

  compression:    zlib

  $ hg debugformat --verbose

  format-variant repo config default

  fncache:         no    yes     yes

  dotencode:       no    yes     yes

  generaldelta:    no    yes     yes

  plain-cl-delta: yes    yes     yes

  compression:    zlib   zlib    zlib

  $ hg debugformat --verbose --config format.usegeneraldelta=no

  format-variant repo config default

  fncache:         no    yes     yes

  dotencode:       no    yes     yes

  generaldelta:    no     no     yes

  plain-cl-delta: yes    yes     yes

  compression:    zlib   zlib    zlib

  $ hg debugformat --verbose --config format.usegeneraldelta=no --color=debug

  format-variant repo config default

  [formatvariant.name.mismatchconfig|fncache:       ][formatvariant.repo.mismatchconfig|  no][formatvariant.config.default|    yes][formatvariant.default|     yes]

  [formatvariant.name.mismatchconfig|dotencode:     ][formatvariant.repo.mismatchconfig|  no][formatvariant.config.default|    yes][formatvariant.default|     yes]

  [formatvariant.name.mismatchdefault|generaldelta:  ][formatvariant.repo.mismatchdefault|  no][formatvariant.config.special|     no][formatvariant.default|     yes]

  [formatvariant.name.uptodate|plain-cl-delta:][formatvariant.repo.uptodate| yes][formatvariant.config.default|    yes][formatvariant.default|     yes]

  [formatvariant.name.uptodate|compression:   ][formatvariant.repo.uptodate| zlib][formatvariant.config.default|   zlib][formatvariant.default|    zlib]

  $ hg debugupgraderepo

  repository lacks features recommended by current config options:

  fncache

     long and reserved filenames may not work correctly; repository performance is sub-optimal

  dotencode

     storage of filenames beginning with a period or space may not work correctly

  generaldelta

     deltas within internal storage are unable to choose optimal revisions; repository is larger and slower than it could be; interaction with other repositories may require extra network and CPU resources, making "hg push" and "hg pull" slower

  performing an upgrade with "--run" will make the following changes:

  requirements

     preserved: revlogv1, store

     added: dotencode, fncache, generaldelta

  fncache

     repository will be more resilient to storing certain paths and performance of certain operations should be improved

  dotencode

     repository will be better able to store files beginning with a space or period

  generaldelta

     repository storage will be able to create optimal deltas; new repository data will be smaller and read times should decrease; interacting with other repositories using this storage model should require less network and CPU resources, making "hg push" and "hg pull" faster

  additional optimizations are available by specifying "--optimize <name>":

  redeltaparent

     deltas within internal storage will be recalculated to choose an optimal base revision where this was not already done; the size of the repository may shrink and various operations may become faster; the first time this optimization is performed could slow down upgrade execution considerably; subsequent invocations should not run noticeably slower

  redeltamultibase

     deltas within internal storage will be recalculated against multiple base revision and the smallest difference will be used; the size of the repository may shrink significantly when there are many merges; this optimization will slow down execution in proportion to the number of merges in the repository and the amount of files in the repository; this slow down should not be significant unless there are tens of thousands of files and thousands of merges

  redeltaall

     deltas within internal storage will always be recalculated without reusing prior deltas; this will likely make execution run several times slower; this optimization is typically not needed

  $ hg --config format.dotencode=false debugupgraderepo

  repository lacks features recommended by current config options:

  fncache

     long and reserved filenames may not work correctly; repository performance is sub-optimal

  generaldelta

     deltas within internal storage are unable to choose optimal revisions; repository is larger and slower than it could be; interaction with other repositories may require extra network and CPU resources, making "hg push" and "hg pull" slower

  repository lacks features used by the default config options:

  dotencode

     storage of filenames beginning with a period or space may not work correctly

  performing an upgrade with "--run" will make the following changes:

  requirements

     preserved: revlogv1, store

     added: fncache, generaldelta

  fncache

     repository will be more resilient to storing certain paths and performance of certain operations should be improved

  generaldelta

     repository storage will be able to create optimal deltas; new repository data will be smaller and read times should decrease; interacting with other repositories using this storage model should require less network and CPU resources, making "hg push" and "hg pull" faster

  additional optimizations are available by specifying "--optimize <name>":

  redeltaparent

     deltas within internal storage will be recalculated to choose an optimal base revision where this was not already done; the size of the repository may shrink and various operations may become faster; the first time this optimization is performed could slow down upgrade execution considerably; subsequent invocations should not run noticeably slower

  redeltamultibase

     deltas within internal storage will be recalculated against multiple base revision and the smallest difference will be used; the size of the repository may shrink significantly when there are many merges; this optimization will slow down execution in proportion to the number of merges in the repository and the amount of files in the repository; this slow down should not be significant unless there are tens of thousands of files and thousands of merges

  redeltaall

     deltas within internal storage will always be recalculated without reusing prior deltas; this will likely make execution run several times slower; this optimization is typically not needed

  $ cd ..

Upgrading a repository that is already modern essentially no-ops

  $ hg init modern

  $ hg -R modern debugupgraderepo --run

  upgrade will perform the following actions:

  requirements

     preserved: dotencode, fncache, generaldelta, revlogv1, store

  beginning upgrade...

  repository locked and read-only

  creating temporary repository to stage migrated data: $TESTTMP/modern/.hg/upgrade.* (glob)

  (it is safe to interrupt this process any time before data migration completes)

  data fully migrated to temporary repository

  marking source repository as being upgraded; clients will be unable to read from repository

  starting in-place swap of repository data

  replaced files will be backed up at $TESTTMP/modern/.hg/upgradebackup.* (glob)

  replacing store...

  store replacement complete; repository was inconsistent for *s (glob)

  finalizing requirements file and making repository readable again

  removing temporary repository $TESTTMP/modern/.hg/upgrade.* (glob)

  copy of old repository backed up at $TESTTMP/modern/.hg/upgradebackup.* (glob)

  the old repository will not be deleted; remove it to free up disk space once the upgraded repository is verified

Upgrading a repository to generaldelta works

  $ hg --config format.usegeneraldelta=false init upgradegd

  $ cd upgradegd

  $ touch f0

  $ hg -q commit -A -m initial

  $ touch f1

  $ hg -q commit -A -m 'add f1'

  $ hg -q up -r 0

  $ touch f2

  $ hg -q commit -A -m 'add f2'

  $ hg debugupgraderepo --run

  upgrade will perform the following actions:

  requirements

     preserved: dotencode, fncache, revlogv1, store

     added: generaldelta

  generaldelta

     repository storage will be able to create optimal deltas; new repository data will be smaller and read times should decrease; interacting with other repositories using this storage model should require less network and CPU resources, making "hg push" and "hg pull" faster

  beginning upgrade...

  repository locked and read-only

  creating temporary repository to stage migrated data: $TESTTMP/upgradegd/.hg/upgrade.* (glob)

  (it is safe to interrupt this process any time before data migration completes)

  migrating 9 total revisions (3 in filelogs, 3 in manifests, 3 in changelog)

  migrating 341 bytes in store; 401 bytes tracked data

  migrating 3 filelogs containing 3 revisions (0 bytes in store; 0 bytes tracked data)

  finished migrating 3 filelog revisions across 3 filelogs; change in size: 0 bytes

  migrating 1 manifests containing 3 revisions (157 bytes in store; 220 bytes tracked data)

  finished migrating 3 manifest revisions across 1 manifests; change in size: 0 bytes

  migrating changelog containing 3 revisions (184 bytes in store; 181 bytes tracked data)

  finished migrating 3 changelog revisions; change in size: 0 bytes

  finished migrating 9 total revisions; total change in store size: 0 bytes

  copying phaseroots

  data fully migrated to temporary repository

  marking source repository as being upgraded; clients will be unable to read from repository

  starting in-place swap of repository data

  replaced files will be backed up at $TESTTMP/upgradegd/.hg/upgradebackup.* (glob)

  replacing store...

  store replacement complete; repository was inconsistent for *s (glob)