Create noindex.cache if missing

[jasagredo]

Fixes #9891 by creating the file if it is missing.

Depends on #10728

QA

This will work on Linux:

cabal init -m -n --simple --lib
mkdir repo
echo "packages: ." > cabal.project
echo "repository local" >> cabal.project
echo "  url: file+noindex://$(pwd)/repo" >> cabal.project
cabal build

For Windows, the path has to be un-cygwinize and prepended by //./ as described in #10728.

---

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[Mikolaj]

Thank you!

[ffaf1]

Very good. Would there be an easy way to add tests?

[ulysses4ever]

CI fails with what seems to be a simple compilation error:

[100 of 143] Compiling Distribution.Client.IndexUtils ( src/Distribution/Client/IndexUtils.hs, /home/runner/work/cabal/cabal/dist-newstyle-validate-ghc-8.8.4/build/x86_64-linux/ghc-8.8.4/cabal-install-3.15.0.0/build/Distribution/Client/IndexUtils.o )

src/Distribution/Client/IndexUtils.hs:1206:57: error:
Error:     • Couldn't match expected type ‘IO (Either String NoIndexCache)’
                  with actual type ‘Index -> IO (Either String NoIndexCache)’
    • Probable cause: ‘readNoIndexCache'’ is applied to too few arguments
      In the second argument of ‘(>>)’, namely ‘readNoIndexCache' index’
      In the expression:
        updatePackageIndexCacheFile verbosity index
          >> readNoIndexCache' index
      In a stmt of a 'do' block:
        if exists then
            structuredDecodeFileOrFail (cacheFile index)
        else
            updatePackageIndexCacheFile verbosity index
              >> readNoIndexCache' index
     |
1206 |     else updatePackageIndexCacheFile verbosity index >> readNoIndexCache' index
     |                                                         ^^^^^^^^^^^^^^^^^^^^^^^

src/Distribution/Client/IndexUtils.hs:1206:75: error:
Error:     • Couldn't match expected type ‘Verbosity’ with actual type ‘Index’
    • In the first argument of ‘readNoIndexCache'’, namely ‘index’
      In the second argument of ‘(>>)’, namely ‘readNoIndexCache' index’
      In the expression:
        updatePackageIndexCacheFile verbosity index
          >> readNoIndexCache' index
     |
1206 |     else updatePackageIndexCacheFile verbosity index >> readNoIndexCache' index
     |                                                                           ^^^^^

Is @jasagredo available to fix it or should we find a volunteer? I optimistically mark it as desirable for the next 3.14 release.

[Mikolaj]

@jasagredo may surprise us in a pleasant way, but I know he's busy, so let's find a volunteer. Anybody?

[mergify]

This pull request has been removed from the queue for the following reason: pull request branch update failed.

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[Mikolaj]

@mergify backport 3.14

[mergify]

backport 3.14

✅ Backports have been created

• #10874 Backport #10730: Create noindex.cache if missing has been created for branch 3.14