Fix #6551 Use action getLatestApplicableVersionAndRev only when needed

Author: mpilgrem

ChangeLog.md

@@ -56,6 +56,8 @@ Bug fixes:
 
 * The `config set snapshot` and `config set resolver` commands now respect the
   presence of a synoymous key.
+* Fix a regression introduced in Stack 2.15.1 that caused a 'no operation'
+  `stack build` to be slower than previously.
 
 ## v2.15.5 - 2024-03-28
 

src/Stack/Build/ConstructPlan.hs

@@ -829,7 +829,6 @@ processDep ::
            MissingPresentDeps
        )
 processDep pkgId name value = do
-  mLatestApplicable <- getLatestApplicableVersionAndRev name range
   eRes <- getCachedDepOrAddDep name
   let failure mLatestApp err =
         Left $ Map.singleton name (range, mLatestApp, err)
@@ -844,6 +843,7 @@ processDep pkgId name value = do
             -- spamming the user too much.
             DependencyPlanFailures _ _  ->
               Couldn'tResolveItsDependencies version
+      mLatestApplicable <- getLatestApplicableVersionAndRev name range
       pure $ failure mLatestApplicable bd
     Right adr
       | isDepTypeLibrary value.depType && not (adrHasLibrary adr) ->
@@ -853,8 +853,9 @@ processDep pkgId name value = do
       inRange <- adrInRange pkgId name range adr
       pure $ if inRange
         then Right $ processAdr adr
-        else failure mLatestApplicable (DependencyMismatch $ adrVersion adr)
-
+        else do
+          mLatestApplicable <- getLatestApplicableVersionAndRev name range
+          failure mLatestApplicable (DependencyMismatch $ adrVersion adr)
  where
   range = value.versionRange
   version = pkgVersion pkgId