Haskell: cap cabal-install make jobs at 64

Fixes Homebrew/homebrew#49509.

Closes Homebrew/homebrew#49511.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/Library/Homebrew/language/haskell.rb b/Library/Homebrew/language/haskell.rb
index 8680df3a1..b2aa1c505 100644
--- a/Library/Homebrew/language/haskell.rb
+++ b/Library/Homebrew/language/haskell.rb
@@ -45,13 +45,17 @@ module Language
       end
 
       def cabal_install(*args)
+        # cabal hardcodes 64 as the maximum number of parallel jobs
+        # https://github.com/Homebrew/homebrew/issues/49509
+        make_jobs = ENV.make_jobs > 64 ? 64 : ENV.make_jobs
+
         # cabal-install's dependency-resolution backtracking strategy can easily
         # need more than the default 2,000 maximum number of "backjumps," since
         # Hackage is a fast-moving, rolling-release target. The highest known
         # needed value by a formula at this time (February 2016) was 43,478 for
         # git-annex, so 100,000 should be enough to avoid most gratuitous
         # backjumps build failures.
-        system "cabal", "install", "--jobs=#{ENV.make_jobs}", "--max-backjumps=100000", *args
+        system "cabal", "install", "--jobs=#{make_jobs}", "--max-backjumps=100000", *args
       end
 
       def cabal_configure(flags)