Suggest quoting case patterns, as for SC2053 (fixes #1682)

CHANGELOG.md

@@ -2,6 +2,9 @@
 ### Fixed
 - `-f diff` no longer claims that it found more issues when it didn't
 
+### Added
+- SC2254: Suggest quoting expansions in case statements
+
 ## v0.7.0 - 2019-07-28
 ### Added
 - Precompiled binaries for macOS and Linux aarch64

src/ShellCheck/Analytics.hs

@@ -125,6 +125,7 @@ nodeChecks = [
     ,checkArithmeticDeref
     ,checkArithmeticBadOctal
     ,checkComparisonAgainstGlob
+    ,checkCaseAgainstGlob
     ,checkCommarrays
     ,checkOrNeq
     ,checkEchoWc
@@ -1338,6 +1339,21 @@ checkComparisonAgainstGlob params (TC_Binary _ SingleBracket op _ word)
 
 checkComparisonAgainstGlob _ _ = return ()
 
+prop_checkCaseAgainstGlob1 = verify checkCaseAgainstGlob "case foo in lol$n) foo;; esac"
+prop_checkCaseAgainstGlob2 = verify checkCaseAgainstGlob "case foo in $(foo)) foo;; esac"
+prop_checkCaseAgainstGlob3 = verifyNot checkCaseAgainstGlob "case foo in *$bar*) foo;; esac"
+checkCaseAgainstGlob _ t =
+    case t of
+        (T_CaseExpression _ _ cases) -> mapM_ check cases
+        _ -> return ()
+  where
+    check (_, list, _) = mapM_ check' list
+    check' expr@(T_NormalWord _ list)
+        -- If it's already a glob, assume that's what the user wanted
+        | not (isGlob expr) && any isQuoteableExpansion list =
+            warn (getId expr) 2254 "Quote expansions in case patterns to match literally rather than as a glob."
+    check' _ = return ()
+
 prop_checkCommarrays1 = verify checkCommarrays "a=(1, 2)"
 prop_checkCommarrays2 = verify checkCommarrays "a+=(1,2,3)"
 prop_checkCommarrays3 = verifyNot checkCommarrays "cow=(1 \"foo,bar\" 3)"