Re: [PATCH] Make -Wint-in-bool-context warn on suspicious shift ops

[Bernd Edlinger <bernd.edlinger@hotmail.de>]

[-- Attachment #1: Type: text/plain, Size: 518 bytes --]

On 10/18/16 19:05, Joseph Myers wrote:
> On Tue, 18 Oct 2016, Bernd Edlinger wrote:
>
>> Hi,
>>
>> this restricts the -Wint-in-bool-context warning to signed shifts,
>> to reduce the number of false positives Markus reported yesterday.
>
> This patch seems to be missing testcases (that warned before the patch
> and don't warn after it).
>

Yes of course.

New patch, this time with a test case, compiled from the linux sample.

Bootstrapped and reg-tested as usual.
Is it OK for trunk?


Bernd.

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: patch-bool-context4.diff --]
[-- Type: text/x-patch; name="patch-bool-context4.diff", Size: 1666 bytes --]

c-family:
2016-10-17  Bernd Edlinger  <bernd.edlinger@hotmail.de>

	* c-common.c (c_common_truthvalue_conversion): Warn only for signed
	integer shift ops in boolean context.

testsuite:
2016-10-17  Bernd Edlinger  <bernd.edlinger@hotmail.de>

	* c-c++-common/Wint-in-bool-context-2.c: New test.

Index: gcc/c-family/c-common.c
===================================================================
--- gcc/c-family/c-common.c	(revision 241270)
+++ gcc/c-family/c-common.c	(working copy)
@@ -3328,8 +3328,10 @@
 					       TREE_OPERAND (expr, 0));
 
     case LSHIFT_EXPR:
-      warning_at (EXPR_LOCATION (expr), OPT_Wint_in_bool_context,
-		  "<< in boolean context, did you mean '<' ?");
+      if (TREE_CODE (TREE_TYPE (expr)) == INTEGER_TYPE
+	  && !TYPE_UNSIGNED (TREE_TYPE (expr)))
+	warning_at (EXPR_LOCATION (expr), OPT_Wint_in_bool_context,
+		    "<< in boolean context, did you mean '<' ?");
       break;
 
     case COND_EXPR:
Index: gcc/testsuite/c-c++-common/Wint-in-bool-context-2.c
===================================================================
--- gcc/testsuite/c-c++-common/Wint-in-bool-context-2.c	(revision 0)
+++ gcc/testsuite/c-c++-common/Wint-in-bool-context-2.c	(working copy)
@@ -0,0 +1,17 @@
+/* { dg-options "-Wint-in-bool-context" } */
+/* { dg-do compile } */
+
+typedef unsigned u32;
+typedef unsigned char u8;
+#define KEYLENGTH 8
+
+int foo (u8 plen, u32 key)
+{
+  if ((plen < KEYLENGTH) && (key << plen)) /* { dg-bogus "boolean context" } */
+    return -1;
+
+  if ((plen << KEYLENGTH) && (key < plen)) /* { dg-warning "boolean context" } */
+    return -2;
+
+  return 0;
+}