re PR c++/17120 (warning: suggest parentheses around assignment used as truth value)

cp:
	PR c++/17120
	* pt.c (tsubst_copy_and_build): Avoid clearing TREE_NO_WARNING for
	MODOP_EXPR.

testsuite:
	* g++.dg/warn/Wparentheses-4.C: New test.

From-SVN: r86351

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 9897a9f4d0db403ea849430f2a1c992697cb800f..2b794f05ea2f1cce4c89b6c1d73117810ab6ed82 100644 (file)
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2004-08-21  Joseph S. Myers  <jsm@polyomino.org.uk>
+
+       PR c++/17120
+       * pt.c (tsubst_copy_and_build): Avoid clearing TREE_NO_WARNING for
+       MODOP_EXPR.
+
 2004-08-20  Kriang Lerdsuwanakij  <lerdsuwa@users.sourceforge.net>
 
        * pt.c (register_specialization): Check DECL_TEMPLATE_SPECIALIZATION

diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index dd88b987fef9bcffb1fe4093420c28001119b859..8ee4be9f804b415f8dddd43f97d677bfc949e0d5 100644 (file)
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -8353,7 +8353,14 @@ tsubst_copy_and_build (tree t,
          (RECUR (TREE_OPERAND (t, 0)),
           TREE_CODE (TREE_OPERAND (t, 1)),
           RECUR (TREE_OPERAND (t, 2)));
-       TREE_NO_WARNING (r) = TREE_NO_WARNING (t);
+       /* TREE_NO_WARNING must be set if either the expression was
+          parenthesized or it uses an operator such as >>= rather
+          than plain assignment.  In the former case, it was already
+          set and must be copied.  In the latter case,
+          build_x_modify_expr sets it and it must not be reset
+          here.  */
+       if (TREE_NO_WARNING (t))
+         TREE_NO_WARNING (r) = TREE_NO_WARNING (t);
        return r;
       }
 

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 6e395b0ad32fe8fe142ac846c5e8fe808a98bbdf..d096a1b696dfbc6531979701f08384ce5883c745 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2004-08-21  Joseph S. Myers  <jsm@polyomino.org.uk>
+
+       PR c++/17120
+       * g++.dg/warn/Wparentheses-4.C: New test.
+
 2004-08-20  Mark Mitchell  <mark@codesourcery.com>
 
        * gcc.dg/darwin-longlong.c: Include <stdlib.h>.

diff --git a/gcc/testsuite/g++.dg/warn/Wparentheses-4.C b/gcc/testsuite/g++.dg/warn/Wparentheses-4.C
new file mode 100644 (file)
index 0000000..2048ed7
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wparentheses-4.C
@@ -0,0 +1,19 @@
+// Test that -Wparentheses does not give bogus warnings in the
+// presence of templates for non-plain assignment.  Bug 17120.
+
+// { dg-do compile }
+// { dg-options "-Wparentheses" }
+
+template<typename _Tp>
+  inline _Tp
+  cmath_power(_Tp __x, unsigned int __n)
+  {
+    while (__n >>= 1)
+      ;
+    return __x;
+  }
+
+int main()
+{
+  cmath_power(1.0, 3);
+}