[C PATCH] Don't print -Waddress comparison warnings for macros (PR c/48778)

[Marek Polacek]

This PR from 2011 reports that -Waddress prints unhelpful warning when the
comparison comes from a macro.  Since I've added from_macro_expansion_at,
this is easy to circumvent.  I'm not so sure we actually want to disable
the warning in the case of a macro, but probably yes.

Bootstrapped/regtested on x86_64-linux, ok for trunk or should I defer to
GCC 7?

2016-03-01  Marek Polacek  <pola...@redhat.com>

        PR c/48778
        * c-typeck.c (build_binary_op): Don't issue -Waddress warnings
        for macro expansions.

        * gcc.dg/Waddress-2.c: New test.

diff --git gcc/c/c-typeck.c gcc/c/c-typeck.c
index 6aa0f03..0f415e0 100644
--- gcc/c/c-typeck.c
+++ gcc/c/c-typeck.c
@@ -11087,7 +11087,8 @@ build_binary_op (location_t location, enum tree_code 
code,
       else if (code0 == POINTER_TYPE && null_pointer_constant_p (orig_op1))
        {
          if (TREE_CODE (op0) == ADDR_EXPR
-             && decl_with_nonnull_addr_p (TREE_OPERAND (op0, 0)))
+             && decl_with_nonnull_addr_p (TREE_OPERAND (op0, 0))
+             && !from_macro_expansion_at (location))
            {
              if (code == EQ_EXPR)
                warning_at (location,
@@ -11107,7 +11108,8 @@ build_binary_op (location_t location, enum tree_code 
code,
       else if (code1 == POINTER_TYPE && null_pointer_constant_p (orig_op0))
        {
          if (TREE_CODE (op1) == ADDR_EXPR
-             && decl_with_nonnull_addr_p (TREE_OPERAND (op1, 0)))
+             && decl_with_nonnull_addr_p (TREE_OPERAND (op1, 0))
+             && !from_macro_expansion_at (location))
            {
              if (code == EQ_EXPR)
                warning_at (location,
diff --git gcc/testsuite/gcc.dg/Waddress-2.c gcc/testsuite/gcc.dg/Waddress-2.c
index e69de29..4d927f6 100644
--- gcc/testsuite/gcc.dg/Waddress-2.c
+++ gcc/testsuite/gcc.dg/Waddress-2.c
@@ -0,0 +1,24 @@
+/* PR c/48778 */
+/* { dg-do compile } */
+/* { dg-options "-Waddress" } */
+
+#define NULL ((void *) 0)
+
+#define M1(b) ((b) != NULL ? 0 : (b))
+#define M2(b) ((b) == NULL ? 0 : (b))
+#define M3(b) (NULL != (b) ? 0 : (b))
+#define M4(b) (NULL == (b) ? 0 : (b))
+
+int
+func (int b)
+{
+  if (M1 (&b) > 0)
+    return 1;
+  if (M2 (&b) > 0)
+    return 2;
+  if (M3 (&b) > 0)
+    return 3;
+  if (M4 (&b) > 0)
+    return 4;
+  return 0;
+}

        Marek