Merge pull request #7237 from phadej/backport-to-3.4-20210109

Cabal/Distribution/FieldGrammar/Class.hs

Cabal/Distribution/FieldGrammar/Parsec.hs

Cabal/Distribution/PackageDescription/FieldGrammar.hs

cabal-install/Distribution/Client/ProjectPlanning.hs

cabal-install/Distribution/Solver/Modular/IndexConversion.hs

cabal-install/Distribution/Solver/Modular/Message.hs

cabal-install/Distribution/Solver/Modular/Tree.hs

cabal-testsuite/PackageTests/Regression/T7234/Fail/M.hs

cabal-testsuite/PackageTests/Regression/T7234/Fail/cabal.out

...estsuite/PackageTests/Regression/T7234/Fail/cabal.project

...estsuite/PackageTests/Regression/T7234/Fail/cabal.test.hs

...tsuite/PackageTests/Regression/T7234/Fail/issue7234.cabal

cabal-testsuite/PackageTests/Regression/T7234/Success/M.hs

...testsuite/PackageTests/Regression/T7234/Success/cabal.out

...suite/PackageTests/Regression/T7234/Success/cabal.project

...suite/PackageTests/Regression/T7234/Success/cabal.test.hs

...ite/PackageTests/Regression/T7234/Success/issue7234.cabal