[PATCH] c++: fix error reporting routines re-entered ICE [PR110175]

[Marek Polacek <polacek@redhat.com>]

Here we get the "error reporting routines re-entered" ICE because
of an unguarded use of warning_at.  While at it, I added a check
for a warning_at just above it.

Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?

	PR c++/110175

gcc/cp/ChangeLog:

	* typeck.cc (cp_build_unary_op): Check tf_warning before warning.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp0x/decltype-110175.C: New test.
---
 gcc/cp/typeck.cc                             | 5 +++--
 gcc/testsuite/g++.dg/cpp0x/decltype-110175.C | 6 ++++++
 2 files changed, 9 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/cpp0x/decltype-110175.C

diff --git a/gcc/cp/typeck.cc b/gcc/cp/typeck.cc
index da591dafc8f..859b133a18d 100644
--- a/gcc/cp/typeck.cc
+++ b/gcc/cp/typeck.cc
@@ -7561,7 +7561,8 @@ cp_build_unary_op (enum tree_code code, tree xarg, bool noconvert,
 	/* [depr.volatile.type] "Postfix ++ and -- expressions and
 	   prefix ++ and -- expressions of volatile-qualified arithmetic
 	   and pointer types are deprecated."  */
-	if (TREE_THIS_VOLATILE (arg) || CP_TYPE_VOLATILE_P (TREE_TYPE (arg)))
+	if ((TREE_THIS_VOLATILE (arg) || CP_TYPE_VOLATILE_P (TREE_TYPE (arg)))
+	    && (complain & tf_warning))
 	  warning_at (location, OPT_Wvolatile,
 		      "%qs expression of %<volatile%>-qualified type is "
 		      "deprecated",
@@ -7592,7 +7593,7 @@ cp_build_unary_op (enum tree_code code, tree xarg, bool noconvert,
 		    return error_mark_node;
 		  }
 		/* Otherwise, [depr.incr.bool] says this is deprecated.  */
-		else
+		else if (complain & tf_warning)
 		  warning_at (location, OPT_Wdeprecated,
 			      "use of an operand of type %qT "
 			      "in %<operator++%> is deprecated",
diff --git a/gcc/testsuite/g++.dg/cpp0x/decltype-110175.C b/gcc/testsuite/g++.dg/cpp0x/decltype-110175.C
new file mode 100644
index 00000000000..39643cafcf8
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/decltype-110175.C
@@ -0,0 +1,6 @@
+// PR c++/110175
+// { dg-do compile { target c++11 } }
+
+template<class T> auto f(T t) -> decltype(++t) { return t; } // { dg-warning "reference" "" { target c++14_down } }
+void f(...) {}
+void g() { f(true); }

base-commit: 5388a43f6a3f348929292998bd6d0c1da6f006de
-- 
2.41.0