fix: prices: Do not try to generate prices when there would be a zero

denominator.

Also correctly generate reverse prices for zero amounts.

hledger/Hledger/Cli/Commands/Prices.hs

@@ -35,16 +35,16 @@ prices opts j = do
     q          = _rsQuery $ reportspec_ opts
     ps         = filter (matchesPosting q) $ allPostings j
     mprices    = jpricedirectives j
-    cprices    = 
+    cprices    =
-      map (stylePriceDirectiveExceptPrecision styles) $ 
+      map (stylePriceDirectiveExceptPrecision styles) $
       concatMap postingsPriceDirectivesFromCosts ps
-    rcprices   = 
+    rcprices   =
-      map (stylePriceDirectiveExceptPrecision styles) $ 
+      map (stylePriceDirectiveExceptPrecision styles) $
-      concatMap (postingsPriceDirectivesFromCosts . postingTransformAmount (mapMixedAmount invertPrice)) 
+      concatMap (postingsPriceDirectivesFromCosts . postingTransformAmount (mapMixedAmount invertPrice))
       ps
-    allprices  = 
+    allprices  =
-      mprices 
+      mprices
-      ++ ifBoolOpt "infer-market-prices" cprices 
+      ++ ifBoolOpt "infer-market-prices" cprices
       ++ ifBoolOpt "infer-reverse-prices" rcprices  -- TODO: shouldn't this show reversed P prices also ? valuation will use them
 
   mapM_ (T.putStrLn . showPriceDirective) $
@@ -79,8 +79,10 @@ invertPrice a =
             a { aprice = Just $ TotalPrice pa' } where
                 pa' = ((1 / aquantity a) `divideAmount` pa) { aprice = Nothing }
         Just (TotalPrice pa) ->
-            a { aquantity = aquantity pa * signum (aquantity a), acommodity = acommodity pa, aprice = Just $ TotalPrice pa' } where
+            a { aquantity = aquantity pa * nonZeroSignum (aquantity a), acommodity = acommodity pa, aprice = Just $ TotalPrice pa' } where
                 pa' = pa { aquantity = abs $ aquantity a, acommodity = acommodity a, aprice = Nothing, astyle = astyle a }
+  where
+    nonZeroSignum x = if x < 0 then -1 else 1
 
 postingsPriceDirectivesFromCosts :: Posting -> [PriceDirective]
 postingsPriceDirectivesFromCosts p = mapMaybe (amountPriceDirectiveFromCost date) . amountsRaw $ pamount p
@@ -89,11 +91,11 @@ postingsPriceDirectivesFromCosts p = mapMaybe (amountPriceDirectiveFromCost date
 amountPriceDirectiveFromCost :: Day -> Amount -> Maybe PriceDirective
 amountPriceDirectiveFromCost d a =
     case aprice a of
-        Nothing -> Nothing
         Just (UnitPrice pa) -> Just
             PriceDirective { pddate = d, pdcommodity = acommodity a, pdamount = pa }
-        Just (TotalPrice pa) -> Just
+        Just (TotalPrice pa) | aquantity a /= 0 -> Just
             PriceDirective { pddate = d, pdcommodity = acommodity a, pdamount = abs (aquantity a) `divideAmount'` pa }
+        _ -> Nothing
 
 -- | Given a map of standard amount display styles, apply the
 -- appropriate one, if any, to this price directive's amount.

hledger/test/prices.test

@@ -80,3 +80,32 @@ P 2019-01-02 X 1.000,1 A
 P 2019-02-01 X 1.000,2345 A
 P 2019-02-02 X 1.000,2 A
 
+<
+;; Total asset value should be 400 USD + 1000 USD = 1400 USD
+2021-10-15 Broker initial balance (equity ABC)
+    Assets:Broker           = 4 ABC @@ 400 USD
+    Equity:Opening Balances
+
+2021-10-15 Broker initial balance (USD)
+    Assets:Broker           = 1000 USD
+    Equity:Opening Balances
+
+# 6. Inferring prices should play well with balance assertions involving mixing
+# of prices and no prices. (#1736)
+$ hledger -f- prices --infer-market-prices
+P 2021-10-15 ABC 100.0 USD
+
+<
+2021-10-15
+    (a)    1 A @@ 0 B
+
+2021-10-16
+    (b)    0 A @@ 1 B
+
+# 7. Gracefully ignore any postings which would result in an infinite price.
+$ hledger -f- prices --infer-market-prices
+P 2021-10-15 A 0.0 B
+
+# 8. Same for reverse prices
+$ hledger -f- prices --infer-reverse-prices
+P 2021-10-16 B 0.0 A