preliminary scoped errors with approximate source location

- scoped traversals can now raise errors which contain the path of the
  current scope and an approximate source location based on preceding
  trace comments, if available
- initially, this new error messaging has only been added for the
  illegal size cast checks in the TypeOf and Cast conversions
- error suite tests can provide a verbose mode expected source location

CHANGELOG.md

@@ -5,6 +5,11 @@
 * Added support for excluding the conversion of unbased unsized literals (e.g.,
   `'1`, `'x`) via `--exclude UnbasedUniszed`
 
+### Other Enhancements
+
+* Certain errors raised during conversion now also provide hierarchical and
+  approximate source location information to help locate the error
+
 ## v0.0.9
 
 ### Breaking Changes

src/Convert/Cast.hs

@@ -115,7 +115,8 @@ convertCastM (Number size) _ _
     where
         maybeInt = numberToInteger size
         Just int = maybeInt
-        illegal s = error $ "size cast width " ++ show size ++ " is not " ++ s
+        illegal = scopedErrorM . msg
+        msg s = "size cast width " ++ show size ++ " is not " ++ s
 convertCastM (Number size) (Number value) signed =
     return $ Number $
         numberCast signed (fromIntegral size') value

src/Convert/Scoper.hs

@@ -57,6 +57,8 @@ module Convert.Scoper
     , withinProcedureM
     , procedureLoc
     , procedureLocM
+    , scopedError
+    , scopedErrorM
     , isLoopVar
     , isLoopVarM
     , loopVarDepth
@@ -68,7 +70,7 @@ module Convert.Scoper
     ) where
 
 import Control.Monad.State.Strict
-import Data.List (findIndices, partition)
+import Data.List (findIndices, intercalate, isPrefixOf, partition)
 import Data.Maybe (isNothing)
 import qualified Data.Map.Strict as Map
 
@@ -105,6 +107,7 @@ data Scopes a = Scopes
     , sProcedureLoc :: [Access]
     , sInjectedItems :: [(Bool, ModuleItem)]
     , sInjectedDecls :: [Decl]
+    , sLatestTrace :: String
     } deriving Show
 
 extractMapping :: Scopes a -> Map.Map Identifier a
@@ -353,6 +356,26 @@ procedureLocM = gets procedureLoc
 procedureLoc :: Scopes a -> [Access]
 procedureLoc = sProcedureLoc
 
+debugLocation :: Scopes a -> String
+debugLocation s =
+    hierarchy ++
+    if null latestTrace
+        then " (use -v to get approximate source location)"
+        else ", near " ++ latestTrace
+    where
+        hierarchy = intercalate "." $ map tierToStr $ sCurrent s
+        latestTrace = sLatestTrace s
+        tierToStr :: Tier -> String
+        tierToStr (Tier "" _) = "<unnamed_block>"
+        tierToStr (Tier x "") = x
+        tierToStr (Tier x y) = x ++ '[' : y ++ "]"
+
+scopedErrorM :: Monad m => String -> ScoperT a m x
+scopedErrorM msg = get >>= flip scopedError msg
+
+scopedError :: Scopes a -> String -> x
+scopedError scopes = error . (++ ", within scope " ++ debugLocation scopes)
+
 isLoopVar :: Scopes a -> Identifier -> Bool
 isLoopVar scopes x = any matches $ sCurrent scopes
     where matches = (== x) . tierIndex
@@ -411,7 +434,10 @@ runScoperT :: Monad m => ScoperT a m x -> m (x, Scopes a)
 runScoperT = flip runStateT initialState
 
 initialState :: Scopes a
-initialState = Scopes [] Map.empty [] [] []
+initialState = Scopes [] Map.empty [] [] [] ""
+
+tracePrefix :: String
+tracePrefix = "Trace: "
 
 scopeModuleItem
     :: forall a m. Monad m
@@ -420,7 +446,7 @@ scopeModuleItem
     -> MapperM (ScoperT a m) GenItem
     -> MapperM (ScoperT a m) Stmt
     -> MapperM (ScoperT a m) ModuleItem
-scopeModuleItem declMapper moduleItemMapper genItemMapper stmtMapper =
+scopeModuleItem declMapperRaw moduleItemMapper genItemMapper stmtMapperRaw =
     wrappedModuleItemMapper
     where
         fullStmtMapper :: Stmt -> ScoperT a m Stmt
@@ -438,6 +464,21 @@ scopeModuleItem declMapper moduleItemMapper genItemMapper stmtMapper =
                 then traverseSinglyNestedStmtsM fullStmtMapper stmt'
                 else fullStmtMapper $ Block Seq "" injected [stmt']
 
+        declMapper :: Decl -> ScoperT a m Decl
+        declMapper decl@(CommentDecl c) =
+            consumeComment c >> return decl
+        declMapper decl = declMapperRaw decl
+
+        stmtMapper :: Stmt -> ScoperT a m Stmt
+        stmtMapper stmt@(CommentStmt c) =
+            consumeComment c >> return stmt
+        stmtMapper stmt = stmtMapperRaw stmt
+
+        consumeComment :: String -> ScoperT a m ()
+        consumeComment c =
+            when (tracePrefix `isPrefixOf` c) $
+                modify' $ \s -> s { sLatestTrace = drop (length tracePrefix) c }
+
         -- converts a decl and adds decls injected during conversion
         declMapper' :: Decl -> ScoperT a m [Decl]
         declMapper' decl = do

src/Convert/TypeOf.hs

@@ -130,7 +130,8 @@ traverseExprM other =
 elaborateSizeCast :: Expr -> Expr -> ST Expr
 elaborateSizeCast (Number size) _ | Just 0 == numberToInteger size =
     -- special case because zero-width ranges cannot be represented
-    error $ "size cast width " ++ show size ++ " is not a positive integer"
+    scopedErrorM $ "size cast width " ++ show size
+        ++ " is not a positive integer"
 elaborateSizeCast size value = do
     t <- typeof value
     force <- isStringParam value

test/error/run.sh

@@ -3,6 +3,9 @@
 runErrorTest() {
     extractFlag pattern $1.sv
     pattern="${flag:-.}"
+    extractFlag location $1.sv
+    location="${flag//./\.}"
+    location="${location:-.}"
 
     runAndCapture $1.sv
     assertFalse "regular conversion should have failed" $result
@@ -15,6 +18,7 @@ runErrorTest() {
     assertNull "verbose stdout should be empty" "$stdout"
     assertNotNull "verbose stderr should not be empty" "$stderr"
     assertMatch "verbose error message" "$stderr" "$pattern"
+    assertMatch "verbose location" "$stderr" "$location[^0-9]"
 }
 
 addTest() {

test/error/size_cast_neg_lit_1.sv

 // pattern: size cast width 1'sb1 is not a positive integer
+// location: size_cast_neg_lit_1.sv:4:13
 module top;
     initial $display((1'sb1)'(2));
 endmodule

test/error/size_cast_neg_lit_2.sv

 // pattern: size cast width 2'sb11 is not a positive integer
+// location: size_cast_neg_lit_2.sv:4:13
 module top;
     initial $display((2'sb11)'(2));
 endmodule

test/error/size_cast_neg_var_1.sv

 // pattern: size cast width 1'sb1 is not a positive integer
+// location: size_cast_neg_var_1.sv:5:13
 module top;
     wire x = 0;
     initial $display((1'sb1)'(x));

test/error/size_cast_neg_var_2.sv

 // pattern: size cast width 2'sb11 is not a positive integer
+// location: size_cast_neg_var_2.sv:5:13
 module top;
     wire x = 0;
     initial $display((2'sb11)'(x));

test/error/size_cast_x_lit.sv

 // pattern: size cast width 1'bx is not an integer
+// location: size_cast_x_lit.sv:4:13
 module top;
     initial $display((1'bx)'(2));
 endmodule

test/error/size_cast_x_var.sv

 // pattern: size cast width 1'bx is not an integer
+// location: size_cast_x_var.sv:5:13
 module top;
     wire x = 0;
     initial $display((1'bx)'(x));

test/error/size_cast_zero_lit.sv

 // pattern: size cast width 0 is not a positive integer
+// location: size_cast_zero_lit.sv:4:13
 module top;
     initial $display((0)'(2));
 endmodule

test/error/size_cast_zero_var.sv

 // pattern: size cast width 0 is not a positive integer
+// location: size_cast_zero_var.sv:5:13
 module top;
     wire x = 0;
     initial $display((0)'(x));