re PR c/59871 (No unused value warning for comma expression)

	PR c/59871
c/
	* c-typeck.c (build_compound_expr): Warn even for right-hand operand
	of a comma expression.
	(emit_side_effect_warnings): Likewise.
libdecnumber/
	* decNumberLocal.h (UBFROMUS, UBFROMUI): Remove last argument.
testsuite/
	* gcc.dg/20020220-2.c: Adjust dg-warning message.
	* gcc.dg/pr59871.c: New test.

From-SVN: r207002

gcc/c/ChangeLog

+2014-01-23  Marek Polacek  <polacek@redhat.com>
+
+	PR c/59871
+	* c-typeck.c (build_compound_expr): Warn even for right-hand operand
+	of a comma expression.
+	(emit_side_effect_warnings): Likewise.
+
 2014-01-23  Balaji V. Iyer  <balaji.v.iyer@intel.com>
 
 	PR c/59825

gcc/c/c-typeck.c

@@ -4778,6 +4778,23 @@ build_compound_expr (location_t loc, tree expr1, tree expr2)
 			"left-hand operand of comma expression has no effect");
 	}
     }
+  else if (TREE_CODE (expr1) == COMPOUND_EXPR
+	   && warn_unused_value)
+    {
+      tree r = expr1;
+      location_t cloc = loc;
+      while (TREE_CODE (r) == COMPOUND_EXPR)
+        {
+	  if (EXPR_HAS_LOCATION (r))
+	    cloc = EXPR_LOCATION (r);
+	  r = TREE_OPERAND (r, 1);
+	}
+      if (!TREE_SIDE_EFFECTS (r)
+	  && !VOID_TYPE_P (TREE_TYPE (r))
+	  && !CONVERT_EXPR_P (r))
+	warning_at (cloc, OPT_Wunused_value,
+	            "right-hand operand of comma expression has no effect");
+    }
 
   /* With -Wunused, we should also warn if the left-hand operand does have
      side-effects, but computes a value which is not used.  For example, in
@@ -9643,6 +9660,23 @@ emit_side_effect_warnings (location_t loc, tree expr)
       if (!VOID_TYPE_P (TREE_TYPE (expr)) && !TREE_NO_WARNING (expr))
 	warning_at (loc, OPT_Wunused_value, "statement with no effect");
     }
+  else if (TREE_CODE (expr) == COMPOUND_EXPR)
+    {
+      tree r = expr;
+      location_t cloc = loc;
+      while (TREE_CODE (r) == COMPOUND_EXPR)
+	{
+	  if (EXPR_HAS_LOCATION (r))
+	    cloc = EXPR_LOCATION (r);
+	  r = TREE_OPERAND (r, 1);
+	}
+      if (!TREE_SIDE_EFFECTS (r)
+	  && !VOID_TYPE_P (TREE_TYPE (r))
+	  && !CONVERT_EXPR_P (r)
+	  && !TREE_NO_WARNING (expr))
+	warning_at (cloc, OPT_Wunused_value,
+		    "right-hand operand of comma expression has no effect");
+    }
   else
     warn_if_unused_value (expr, loc);
 }

gcc/testsuite/ChangeLog

+2014-01-23  Marek Polacek  <polacek@redhat.com>
+
+	PR c/59871
+	* gcc.dg/20020220-2.c: Adjust dg-warning message.
+	* gcc.dg/pr59871.c: New test.
+
 2014-01-23  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/58980

gcc/testsuite/gcc.dg/20020220-2.c

 /* PR c/4697
-   Test whether value computed not used warning is given for compound
+   Test whether operand has no effect warning is given for compound
    expression.  */
 /* { dg-do compile } */
 /* { dg-options "-O2 -Wunused" } */
@@ -7,6 +7,6 @@
 int b;
 int foo (int a)
 {
-  a = a + 1, 5 * b;	/* { dg-warning "value computed is not used" } */
+  a = a + 1, 5 * b; /* { dg-warning "right-hand operand of comma expression has no effect" } */
   return a;
 }

gcc/testsuite/gcc.dg/pr59871.c

+/* PR c/59871 */
+/* { dg-do compile } */
+/* { dg-options "-Wunused" } */
+
+extern int bar ();
+
+void
+foo (int *p, int i)
+{
+  p[0] = (bar (), 1, bar ()); /* { dg-warning "right-hand operand of comma expression has no effect" } */
+  p[1] = (1, bar ()); /* { dg-warning "left-hand operand of comma expression has no effect" } */
+  bar (), 1, bar (); /* { dg-warning "right-hand operand of comma expression has no effect" } */
+  bar (), 1; /* { dg-warning "right-hand operand of comma expression has no effect" } */
+  1, bar (); /* { dg-warning "left-hand operand of comma expression has no effect" } */
+  (bar (), 1); /* { dg-warning "right-hand operand of comma expression has no effect" } */
+  bar (), 5 * i; /* { dg-warning "right-hand operand of comma expression has no effect" } */
+  (bar (), 5 * i); /* { dg-warning "right-hand operand of comma expression has no effect" } */
+  (bar (), (bar (), (bar (), (bar (), (bar (), (bar (), (bar (), 7))))))); /* { dg-warning "right-hand operand of comma expression has no effect" } */
+  bar (), (bar (), (bar (), (bar (), (bar (), (bar (), (bar (), 7)))))); /* { dg-warning "right-hand operand of comma expression has no effect" } */
+  bar (), (bar (), (bar (), (bar (), (bar (), (bar (), (7, bar ())))))); /* { dg-warning "left-hand operand of comma expression has no effect" } */
+  (bar (), (bar (), (bar (), (bar (), (bar (), (bar (), (7, bar ()))))))); /* { dg-warning "left-hand operand of comma expression has no effect" } */
+}

libdecnumber/ChangeLog

+2014-01-23  Marek Polacek  <polacek@redhat.com>
+
+	PR c/59871
+	* decNumberLocal.h (UBFROMUS, UBFROMUI): Remove last argument.
+
 2014-01-02  Richard Sandiford  <rdsandiford@googlemail.com>
 
 	Update copyright years

libdecnumber/decNumberLocal.h

@@ -153,10 +153,9 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
   #define UBTOUI(b)  (memcpy((void *)&uiwork, b, 4), uiwork)
 
   /* Store a uInt, etc., into bytes starting at a char* or uByte*.    */
-  /* Returns i, evaluated, for convenience; has to use uiwork because */
-  /* i may be an expression.					      */
-  #define UBFROMUS(b, i)  (uswork=(i), memcpy(b, (void *)&uswork, 2), uswork)
-  #define UBFROMUI(b, i)  (uiwork=(i), memcpy(b, (void *)&uiwork, 4), uiwork)
+  /* Has to use uiwork because i may be an expression.		      */
+  #define UBFROMUS(b, i)  (uswork=(i), memcpy(b, (void *)&uswork, 2))
+  #define UBFROMUI(b, i)  (uiwork=(i), memcpy(b, (void *)&uiwork, 4))
 
   /* X10 and X100 -- multiply integer i by 10 or 100		      */
   /* [shifts are usually faster than multiply; could be conditional]  */