From 7f5a63d43115f18742e6bdfd5e7476bc9bff5932 Mon Sep 17 00:00:00 2001
From: Michael Sloan <mgsloan@gmail.com>
Date: Sun, 6 Aug 2017 17:07:56 -0700
Subject: [PATCH] Only plan to build a target if some of its components will
 built #2862

---
 ChangeLog.md              |  2 ++
 src/Stack/Build/Source.hs | 15 +++++++++++++--
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/ChangeLog.md b/ChangeLog.md
index 6b0d6ad795..bf3c94a18e 100644
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -51,6 +51,8 @@ Bug fixes:
 * Fixed an issue where Stack wouldn't detect missing Docker images
   properly with newer Docker versions.
   [#3171](https://github.com/commercialhaskell/stack/pull/3171)
+* Previously, cabal files with just test-suite could cause build to fail
+  ([#2862](https://github.com/commercialhaskell/stack/issues/2862))
 
 
 ## 1.5.1
diff --git a/src/Stack/Build/Source.hs b/src/Stack/Build/Source.hs
index 98c3bf4822..fca5ee7094 100644
--- a/src/Stack/Build/Source.hs
+++ b/src/Stack/Build/Source.hs
@@ -183,12 +183,23 @@ loadLocalPackage boptsCli targets (name, lpv) = do
                     )
                 Nothing -> mempty
 
+        -- See https://github.com/commercialhaskell/stack/issues/2862
+        isWanted = case mtarget of
+            Nothing -> False
+            -- FIXME: When issue #1406 ("stack 0.1.8 lost ability to
+            -- build individual executables or library") is resolved,
+            -- 'packageHasLibrary' is only relevant if the library is
+            -- part of the target spec.
+            Just _ -> packageHasLibrary pkg || not (Set.null allComponents)
+
         filterSkippedComponents = Set.filter (not . (`elem` boptsSkipComponents bopts))
 
         (exes, tests, benches) = (filterSkippedComponents exeCandidates,
                                   filterSkippedComponents testCandidates,
                                   filterSkippedComponents benchCandidates)
 
+        allComponents = toComponents exes tests benches
+
         toComponents e t b = Set.unions
             [ Set.map CExe e
             , Set.map CTest t
@@ -254,8 +265,8 @@ loadLocalPackage boptsCli targets (name, lpv) = do
         , lpNewBuildCache = newBuildCache
         , lpCabalFile = lpvCabalFP lpv
         , lpDir = lpvRoot lpv
-        , lpWanted = isJust mtarget
-        , lpComponents = toComponents exes tests benches
+        , lpWanted = isWanted
+        , lpComponents = allComponents
         -- TODO: refactor this so that it's easier to be sure that these
         -- components are indeed unbuildable.
         --