4267 Add --exact flag to the list command

This PR adds `--exact` flag to the cabal list command which
enables exact match on the package name while searching.

Author: v0d1ch

Cabal/Distribution/Simple/Program/HcPkg.hs

@@ -473,7 +473,7 @@ listInvocation hpi _verbosity packagedb =
       progInvokeOutputEncoding = IOEncodingUTF8
     }
   where
-    args = ["list", "--simple-output", packageDbOpts hpi packagedb]
+    args = ["list", "--simple-output", "--exact", packageDbOpts hpi packagedb]
         ++ verbosityOpts hpi silent
            -- We use verbosity level 'silent' because it is important that we
            -- do not contaminate the output with info/debug messages.

cabal-install/Distribution/Client/List.hs

@@ -14,7 +14,7 @@ module Distribution.Client.List (
   ) where
 
 import Distribution.Package
-         ( PackageName, Package(..), packageName
+         ( PackageName, Package(..), packageName, unPackageName
          , packageVersion, UnitId )
 import Distribution.Types.Dependency
 import Distribution.Types.UnqualComponentName
@@ -106,11 +106,11 @@ getPkgList verbosity packageDBs repoCtxt comp progdb listFlags pats = do
                         (         PackageIndex.allPackages sourcePkgIndex)
 
             -- gather info for packages matching search term
-          | otherwise = pkgsInfoMatching
+          | otherwise = pkgsInfoMatching exactMatch
 
         pkgsInfoMatching ::
-          [(PackageName, [Installed.InstalledPackageInfo], [UnresolvedSourcePackage])]
-        pkgsInfoMatching =
+          Bool -> [(PackageName, [Installed.InstalledPackageInfo], [UnresolvedSourcePackage])]
+        pkgsInfoMatching exact =
           let matchingInstalled = matchingPackages
                                   InstalledPackageIndex.searchByNameSubstring
                                   installedPkgIndex
@@ -119,7 +119,10 @@ getPkgList verbosity packageDBs repoCtxt comp progdb listFlags pats = do
                                    concatMap snd
                                    (PackageIndex.searchByNameSubstring idx n))
                                  sourcePkgIndex
-          in mergePackages matchingInstalled matchingSource
+              mergedPackages = mergePackages matchingInstalled matchingSource
+          in if exact
+              then filterPackages mergedPackages
+              else mergedPackages
 
         matches :: [PackageDisplayInfo]
         matches = [ mergePackageInfo pref
@@ -131,6 +134,13 @@ getPkgList verbosity packageDBs repoCtxt comp progdb listFlags pats = do
     return matches
   where
     onlyInstalled = fromFlag (listInstalled listFlags)
+    exactMatch = fromFlag (listExactMatch listFlags)
+    filterPackages :: [(PackageName, a, b)] -> [(PackageName, a, b)]
+    filterPackages =
+      filter
+        (\(package,_,_) ->
+            unPackageName package `elem` pats
+        )
     matchingPackages search index =
       [ pkg
       | pat <- pats

cabal-install/Distribution/Client/Setup.hs

@@ -1623,6 +1623,7 @@ instance Semigroup GetFlags where
 data ListFlags = ListFlags {
     listInstalled    :: Flag Bool,
     listSimpleOutput :: Flag Bool,
+    listExactMatch   :: Flag Bool,
     listVerbosity    :: Flag Verbosity,
     listPackageDBs   :: [Maybe PackageDB]
   } deriving Generic
@@ -1631,6 +1632,7 @@ defaultListFlags :: ListFlags
 defaultListFlags = ListFlags {
     listInstalled    = Flag False,
     listSimpleOutput = Flag False,
+    listExactMatch   = Flag False,
     listVerbosity    = toFlag normal,
     listPackageDBs   = []
   }
@@ -1666,6 +1668,10 @@ listCommand = CommandUI {
             "Print in a easy-to-parse format"
             listSimpleOutput (\v flags -> flags { listSimpleOutput = v })
             trueArg
+        , option [] ["exact"]
+            "Print only exact match"
+            listExactMatch (\v flags -> flags { listExactMatch = v })
+            trueArg
 
         , option "" ["package-db"]
           (   "Append the given package database to the list of package"

cabal-install/changelog

@@ -1,6 +1,8 @@
 -*-change-log-*-
 
 3.2.0.0 Someone <mailto:[email protected]> February 2020
+	* Add `--exact` flag to `cabal list` command that enables exact match on the
+	  search package name (#4267)
 	* `v2-build` (and other `v2-`prefixed commands) now accept the
 	  `--benchmark-option(s)` flags, which pass options to benchmark executables
 	  (analogous to how `--test-option(s)` works). (#6209)

cabal-testsuite/Test/Cabal/Monad.hs

@@ -412,7 +412,7 @@ mkNormalizerEnv = do
     -- Arguably we should use Cabal's APIs but I am too lazy
     -- to remember what it is
     list_out <- liftIO $ readProcess (programPath ghc_pkg_program)
-                      ["list", "--global", "--simple-output"] ""
+                      ["list", "--global", "--simple-output", "--exact"] ""
     return NormalizerEnv {
         normalizerRoot
             = addTrailingPathSeparator (testSourceDir env),

solver-benchmarks/HackageBenchmark.hs

@@ -164,7 +164,7 @@ hackageBenchmarkMain = do
           if null argPackages
           then do
             putStrLn $ "Obtaining the package list (using " ++ argCabal1 ++ ") ..."
-            list <- readProcess argCabal1 ["list", "--simple-output"] ""
+            list <- readProcess argCabal1 ["list", "--simple-output", "--exact"] ""
             return $ nub [mkPackageName $ head (words line) | line <- lines list]
           else do
             putStrLn "Using given package list ..."