verifyFetchedTarball has the effect of deserialising the index tarball
(see call to Sec.withIndex).

verifyFetchedTarball is called individually for each package in the
build plan (see ProjectPlanning.hs). Not once per repo.

The hackage tarball is now 880mb so it takes a non significant amount of
time to deserialise this (much better after haskell/tar#95).

This code path is important as it can add 1s with these 38 calls on to
the initial load of a project and scales linearly with the size of your
build tree.

Reproducer: Simple project with "lens" dependency deserialises the index tarball 38 times.

Solution: Refactor verifyFetchedTarball to run once per repo rather than once per package.

In future it would be much better to refactor this function so that the
items are not immediately grouped and ungrouped but I didn't want to
take that on immediately.

Fixes #10110

Ignore because it warns about missing MachDeps.h

Phil de Joux authored 1 year ago and Artem Pelenitsyn committed 1 year ago

* hlint --default -j . > .hlint.yaml

* Ignore modules that #include "MachDeps.h"

  Warning: Can't find file "MachDeps.h" in directories
	./cabal-testsuite/PackageTests/CmmSources/src
	.
  Asked for by: ./cabal-testsuite/PackageTests/CmmSources/src/Demo.hs  at line 8 col 1

  Warning: Can't find file "MachDeps.h" in directories
	./cabal-testsuite/PackageTests/CmmSourcesDyn/src
	.
  Asked for by: ./cabal-testsuite/PackageTests/CmmSourcesDyn/src/Demo.hs  at line 8 col 1

* Ignore the manually generated Lexer.hs

	templates/Lexer.x:10:1-20: Warning: Use fewer LANGUAGE pragmas
	Found:
	  {-# LANGUAGE CPP #-}
	  {-# LANGUAGE CPP #-}

	Perhaps:
	  {-# LANGUAGE CPP #-}

	1 hint

* Ignore templates/Paths_pkg.template.hs for its parse error

* Ignore templates/SPDX*.hs for their parse errors

* Add a linting workflow and rename the formatting one

* Redo default configuration with hlint-3.5

	I had mistakenly used a development build before:

	$ hlint --version
	HLint v3.6.20230213, (C) Neil Mitchell 2006-2022

* Shorten github workflow