Re-add warnings about 'declare var = value' (fixes #2279)

CHANGELOG.md

@@ -4,6 +4,7 @@
 - SC2289: Warn when command name contains tabs or linefeeds
 
 ### Fixed
+- SC2290: Warn about misused = in declare & co, which were not caught by SC2270+
 
 ### Changed
 - SC2048: Warning about $\* now also applies to ${array[\*]}

src/ShellCheck/Checks/Commands.hs

@@ -95,6 +95,11 @@ commandChecks = [
     ,checkSourceArgs
     ,checkChmodDashr
     ,checkXargsDashi
+    ,checkArgComparison "local"
+    ,checkArgComparison "declare"
+    ,checkArgComparison "export"
+    ,checkArgComparison "readonly"
+    ,checkArgComparison "typeset"
     ]
 
 optionalChecks = map fst optionalCommandChecks
@@ -1143,5 +1148,31 @@ checkXargsDashi = CommandCheck (Basename "xargs") f
         return $ info (getId option) 2267 "GNU xargs -i is deprecated in favor of -I{}"
     parseOpts = getBsdOpts "0oprtxadR:S:J:L:l:n:P:s:e:E:i:I:"
 
+
+prop_checkArgComparison1 = verify (checkArgComparison "declare") "declare a = b"
+prop_checkArgComparison2 = verify (checkArgComparison "declare") "declare a =b"
+prop_checkArgComparison3 = verifyNot (checkArgComparison "declare") "declare a=b"
+prop_checkArgComparison4 = verify (checkArgComparison "export") "export a +=b"
+prop_checkArgComparison7 = verifyNot (checkArgComparison "declare") "declare -a +i foo"
+-- This mirrors checkSecondArgIsComparison but for arguments to local/readonly/declare/export
+checkArgComparison str = CommandCheck (Exactly str) wordsWithEqual
+  where
+    wordsWithEqual t = mapM_ check $ drop 1 $ arguments t
+    check arg = sequence_ $ do
+        str <- getLeadingUnquotedString arg
+        case str of
+            '=':_ ->
+                return $ err (headId arg) 2290 $
+                    "Remove spaces around = to assign."
+            '+':'=':_ ->
+                return $ err (headId arg) 2290 $
+                    "Remove spaces around += to append."
+            _ -> Nothing
+
+    headId t =
+        case t of
+            T_NormalWord _ (x:_) -> getId x
+            _ -> getId t
+
 return []
 runTests =  $( [| $(forAllProperties) (quickCheckWithResult (stdArgs { maxSuccess = 1 }) ) |])