From d985380f4833c0b318dd3dc67ad0bd1bbc2e45f3 Mon Sep 17 00:00:00 2001
From: Vidar Holen <spam@vidarholen.net>
Date: Sat, 31 Oct 2015 14:48:08 -0700
Subject: [PATCH] Consider "echo $(<file)" a bashism, and don't warn about
 UUOE.

---
 ShellCheck/ASTLib.hs    |  8 ++++++++
 ShellCheck/Analytics.hs | 20 ++++++++++++++++----
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/ShellCheck/ASTLib.hs b/ShellCheck/ASTLib.hs
index 9ef29b5..c1a64e0 100644
--- a/ShellCheck/ASTLib.hs
+++ b/ShellCheck/ASTLib.hs
@@ -227,6 +227,14 @@ isAssignment t =
         T_Annotation _ _ w -> isAssignment w
         otherwise -> False
 
+isOnlyRedirection t =
+    case t of
+        T_Pipeline _ _ [x] -> isOnlyRedirection x
+        T_Annotation _ _ w -> isOnlyRedirection w
+        T_Redirecting _ (_:_) c -> isOnlyRedirection c
+        T_SimpleCommand _ [] [] -> True
+        otherwise -> False
+
 isFunction t = case t of T_Function {} -> True; _ -> False
 
 -- Get the list of commands from tokens that contain them, such as
diff --git a/ShellCheck/Analytics.hs b/ShellCheck/Analytics.hs
index 6495974..01f92da 100644
--- a/ShellCheck/Analytics.hs
+++ b/ShellCheck/Analytics.hs
@@ -602,6 +602,8 @@ prop_checkBashisms36= verifyNot checkBashisms "#!/bin/dash\nread -p foo -r bar"
 prop_checkBashisms37= verifyNot checkBashisms "HOSTNAME=foo; echo $HOSTNAME"
 prop_checkBashisms38= verify checkBashisms "RANDOM=9; echo $RANDOM"
 prop_checkBashisms39= verify checkBashisms "foo-bar() { true; }"
+prop_checkBashisms40= verify checkBashisms "echo $(<file)"
+prop_checkBashisms41= verify checkBashisms "echo `<file`"
 checkBashisms params = bashism
   where
     isDash = shellType params == Dash
@@ -669,6 +671,11 @@ checkBashisms params = bashism
     bashism (T_Function id _ _ str _) | not (isVariableName str) =
         warnMsg id "naming functions outside [a-zA-Z_][a-zA-Z0-9_]* is"
 
+    bashism (T_DollarExpansion id [x]) | isOnlyRedirection x =
+        warnMsg id "$(<file) to read files is"
+    bashism (T_Backticked id [x]) | isOnlyRedirection x =
+        warnMsg id "`<file` to read files is"
+
     bashism t@(T_SimpleCommand _ _ (cmd:arg:_))
         | t `isCommand` "echo" && "-" `isPrefixOf` argString =
             unless ("--" `isPrefixOf` argString) $ -- echo "-----"
@@ -1635,17 +1642,21 @@ checkPrintfVar _ = checkUnqualifiedCommand "printf" (const f) where
 
 -- Check whether a word is entirely output from a single command
 tokenIsJustCommandOutput t = case t of
-    T_NormalWord id [T_DollarExpansion _ _] -> True
-    T_NormalWord id [T_DoubleQuoted _ [T_DollarExpansion _ _]] -> True
-    T_NormalWord id [T_Backticked _ _] -> True
-    T_NormalWord id [T_DoubleQuoted _ [T_Backticked _ _]] -> True
+    T_NormalWord id [T_DollarExpansion _ cmds] -> check cmds
+    T_NormalWord id [T_DoubleQuoted _ [T_DollarExpansion _ cmds]] -> check cmds
+    T_NormalWord id [T_Backticked _ cmds] -> check cmds
+    T_NormalWord id [T_DoubleQuoted _ [T_Backticked _ cmds]] -> check cmds
     _ -> False
+  where
+    check [x] = not $ isOnlyRedirection x
+    check _ = False
 
 prop_checkUuoeCmd1 = verify checkUuoeCmd "echo $(date)"
 prop_checkUuoeCmd2 = verify checkUuoeCmd "echo `date`"
 prop_checkUuoeCmd3 = verify checkUuoeCmd "echo \"$(date)\""
 prop_checkUuoeCmd4 = verify checkUuoeCmd "echo \"`date`\""
 prop_checkUuoeCmd5 = verifyNot checkUuoeCmd "echo \"The time is $(date)\""
+prop_checkUuoeCmd6 = verifyNot checkUuoeCmd "echo \"$(<file)\""
 checkUuoeCmd _ = checkUnqualifiedCommand "echo" (const f) where
     msg id = style id 2005 "Useless echo? Instead of 'echo $(cmd)', just use 'cmd'."
     f [token] = when (tokenIsJustCommandOutput token) $ msg (getId token)
@@ -1659,6 +1670,7 @@ prop_checkUuoeVar5 = verify checkUuoeVar "foo \"$(echo \"$(date) value:\" $value
 prop_checkUuoeVar6 = verifyNot checkUuoeVar "foo \"$(echo files: *.png)\""
 prop_checkUuoeVar7 = verifyNot checkUuoeVar "foo $(echo $(bar))" -- covered by 2005
 prop_checkUuoeVar8 = verifyNot checkUuoeVar "#!/bin/sh\nz=$(echo)"
+prop_checkUuoeVar9 = verify checkUuoeVar "foo $(echo $(<file))"
 checkUuoeVar _ p =
     case p of
         T_Backticked id [cmd] -> check id cmd