Don't warn about grep pattern issues when using -F.

ShellCheck/ASTLib.hs

@@ -93,7 +93,7 @@ oversimplify token =
         (T_Annotation _ _ s) -> oversimplify s
         -- Workaround for let "foo = bar" parsing
         (TA_Sequence _ [TA_Expansion _ v]) -> concatMap oversimplify v
-        otherwise -> []
+        _ -> []
 
 
 -- Turn a SimpleCommand foo -avz --bar=baz into args "a", "v", "z", "bar",
@@ -115,6 +115,9 @@ getAllFlags = getFlagsUntil (== "--")
 -- Get all flags in a BSD way, up until first non-flag argument or --
 getLeadingFlags = getFlagsUntil (\x -> x == "--" || (not $ "-" `isPrefixOf` x))
 
+-- Check if a command has a flag.
+hasFlag cmd str = str `elem` (map snd $ getAllFlags cmd)
+
 
 -- Given a T_DollarBraced, return a simplified version of the string contents.
 bracedString (T_DollarBraced _ l) = concat $ oversimplify l

ShellCheck/Checks/Commands.hs

@@ -194,16 +194,20 @@ prop_checkGrepRe8 = verify checkGrepRe "ls | grep foo*.jpg"
 prop_checkGrepRe9 = verifyNot checkGrepRe "grep '[0-9]*' file"
 prop_checkGrepRe10= verifyNot checkGrepRe "grep '^aa*' file"
 prop_checkGrepRe11= verifyNot checkGrepRe "grep --include=*.png foo"
+prop_checkGrepRe12= verifyNot checkGrepRe "grep -F 'Foo*' file"
 
-checkGrepRe = CommandCheck (Basename "grep") (f . arguments) where
+checkGrepRe = CommandCheck (Basename "grep") check where
+    check cmd = f cmd (arguments cmd)
     -- --regex=*(extglob) doesn't work. Fixme?
     skippable (Just s) = not ("--regex=" `isPrefixOf` s) && "-" `isPrefixOf` s
     skippable _ = False
-    f [] = return ()
+    f _ [] = return ()
-    f (x:r) | skippable (getLiteralStringExt (const $ return "_") x) = f r
+    f cmd (x:r) | skippable (getLiteralStringExt (const $ return "_") x) = f cmd r
-    f (re:_) = do
+    f cmd (re:_) = do
         when (isGlob re) $
             warn (getId re) 2062 "Quote the grep pattern so the shell won't interpret it."
+
+        unless (cmd `hasFlag` "F") $ do
             let string = concat $ oversimplify re
             if isConfusedGlobRegex string then
                 warn (getId re) 2063 "Grep uses regex, but this looks like a glob."