From 9af38e7870e42df011282011e8417c5d4aadf923 Mon Sep 17 00:00:00 2001
From: Zachary Snow <zach@zachjs.com>
Date: Sun, 16 Feb 2020 15:43:55 -0500
Subject: [PATCH] globally imported items are selectively nested

---
 src/Convert/NestPI.hs        |  8 ++------
 src/Convert/Package.hs       | 19 ++++++++++++++-----
 test/basic/unused_imports.sv |  8 ++++++++
 test/basic/unused_imports.v  |  4 ++++
 4 files changed, 28 insertions(+), 11 deletions(-)
 create mode 100644 test/basic/unused_imports.sv
 create mode 100644 test/basic/unused_imports.v

diff --git a/src/Convert/NestPI.hs b/src/Convert/NestPI.hs
index 75332a9..a0b2ba1 100644
--- a/src/Convert/NestPI.hs
+++ b/src/Convert/NestPI.hs
@@ -31,6 +31,7 @@ convert =
                     (traverseDescriptions . convertDescription)
                     curr
         isPI :: Description -> Bool
+        isPI (PackageItem Import{}) = False
         isPI (PackageItem item) = piName item /= Nothing
         isPI _ = False
 
@@ -55,8 +56,7 @@ convertDescription pis (orig @ Part{}) =
             , collectTypesM $ collectNestedTypesM collectTypenamesM
             , collectExprsM $ collectNestedExprsM collectIdentsM
             ]
-        neededPIs = Set.difference (Set.union usedPIs imports) existingPIs
-        imports = Map.keysSet $ Map.filter isImport pis
+        neededPIs = Set.difference usedPIs existingPIs
         newItems = map MIPackageItem $ Map.elems $
             Map.restrictKeys pis neededPIs
         -- place data declarations at the beginning to obey declaration
@@ -104,7 +104,3 @@ piName (Decl (CommentDecl          _)) = Nothing
 piName (Import x y) = Just $ show $ Import x y
 piName (Export    _) = Nothing
 piName (Directive _) = Nothing
-
-isImport :: PackageItem -> Bool
-isImport Import{} = True
-isImport _ = False
diff --git a/src/Convert/Package.hs b/src/Convert/Package.hs
index 217dbe2..379e3e3 100644
--- a/src/Convert/Package.hs
+++ b/src/Convert/Package.hs
@@ -53,7 +53,7 @@ convertFile :: Packages -> AST -> AST
 convertFile packages ast =
     (++) globalItems $
     filter (not . isCollected) $
-    traverseDescriptions (traverseDescription packages) $
+    concatMap (traverseDescription packages) $
     ast
     where
         globalItems = map PackageItem $
@@ -127,11 +127,20 @@ collectDescriptionM (Package _ name items) =
         isImport _ = False
 collectDescriptionM _ = return ()
 
-traverseDescription :: Packages -> Description -> Description
-traverseDescription packages description =
-    traverseModuleItems (traverseModuleItem existingItemNames packages)
-    description
+traverseDescription :: Packages -> Description -> [Description]
+traverseDescription packages (PackageItem (Import x y)) =
+    map (\(MIPackageItem item) -> PackageItem item) items
     where
+        orig = Part [] False Module Inherit "DNE" []
+            [MIPackageItem $ Import x y]
+        [orig'] = traverseDescription packages orig
+        Part [] False Module Inherit "DNE" [] items = orig'
+traverseDescription packages description =
+    [description']
+    where
+        description' = traverseModuleItems
+            (traverseModuleItem existingItemNames packages)
+            description
         existingItemNames = execWriter $
             collectModuleItemsM writePIName description
         writePIName :: ModuleItem -> Writer Idents ()
diff --git a/test/basic/unused_imports.sv b/test/basic/unused_imports.sv
new file mode 100644
index 0000000..5e6cf3c
--- /dev/null
+++ b/test/basic/unused_imports.sv
@@ -0,0 +1,8 @@
+package P;
+    localparam FOO = 1;
+    localparam BAR = 2;
+endpackage
+import P::*;
+module top;
+    initial $display(FOO);
+endmodule
diff --git a/test/basic/unused_imports.v b/test/basic/unused_imports.v
new file mode 100644
index 0000000..8b8085f
--- /dev/null
+++ b/test/basic/unused_imports.v
@@ -0,0 +1,4 @@
+module top;
+    localparam FOO = 1;
+    initial $display(FOO);
+endmodule