On 2015.08.29 at 09:08 -0400, Jason Merrill wrote:
> On 08/29/2015 06:14 AM, Markus Trippelsdorf wrote:
> > + if (integer_nonzerop (IF_COND (t)) && !RECUR (THEN_CLAUSE (t), any))
> > + return false;
> > + if (integer_zerop (IF_COND (t)) && !RECUR (ELSE_CLAUSE (t), any))
> > + return false;
>
> Actually, I think we can remove the IF_STMT code entirely and move the
> case label to the COND_EXPR case.
>
> Also, please add a comment explaining why we aren't checking
> SWITCH_STMT_BODY.
Done and tested on ppc64le.
PR c++/67371
* constexpr.c (potential_constant_expression_1): Remove IF_STMT
case. Move label to COND_EXPR case. Remove checking of
SWITCH_STMT_BODY.
diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c
index 1eacb8be9a44..0ff9b088cc26 100644
--- a/gcc/cp/constexpr.c
+++ b/gcc/cp/constexpr.c
@@ -4273,15 +4273,6 @@ potential_constant_expression_1 (tree t, bool want_rval,
bool strict,
return false;
return true;
- case IF_STMT:
- if (!RECUR (IF_COND (t), rval))
- return false;
- if (!RECUR (THEN_CLAUSE (t), any))
- return false;
- if (!RECUR (ELSE_CLAUSE (t), any))
- return false;
- return true;
-
case DO_STMT:
if (!RECUR (DO_COND (t), rval))
return false;
@@ -4310,8 +4301,8 @@ potential_constant_expression_1 (tree t, bool want_rval,
bool strict,
case SWITCH_STMT:
if (!RECUR (SWITCH_STMT_COND (t), rval))
return false;
- if (!RECUR (SWITCH_STMT_BODY (t), any))
- return false;
+ /* FIXME we don't check SWITCH_STMT_BODY currently, because even
+ unreachable labels would be checked. */
return true;
case STMT_EXPR:
@@ -4592,6 +4583,7 @@ potential_constant_expression_1 (tree t, bool want_rval,
bool strict,
return false;
return true;
+ case IF_STMT:
case COND_EXPR:
case VEC_COND_EXPR:
/* If the condition is a known constant, we know which of the legs we
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-new.C
b/gcc/testsuite/g++.dg/cpp1y/constexpr-new.C
new file mode 100644
index 000000000000..7241fefc41e5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-new.C
@@ -0,0 +1,11 @@
+// { dg-do compile { target c++14 } }
+
+constexpr int *f4(bool b) {
+ if (b) {
+ return nullptr;
+ } else {
+ return new int{42}; // { dg-error "call to non-constexpr" }
+ }
+}
+static_assert(f4(true) == nullptr, "");
+static_assert(f4(false) == nullptr, ""); // { dg-error "non-constant
condition" }
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-throw.C
b/gcc/testsuite/g++.dg/cpp1y/constexpr-throw.C
new file mode 100644
index 000000000000..ac90051d5e99
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-throw.C
@@ -0,0 +1,34 @@
+// { dg-do compile { target c++14 } }
+
+constexpr void f1() {
+ if (false)
+ throw;
+}
+
+constexpr void f2() {
+ if (true)
+ throw;
+} // { dg-error "not a constant-expression" }
+
+constexpr void f3() {
+ if (false)
+ ;
+ else
+ throw;
+}// { dg-error "not a constant-expression" }
+
+constexpr void f4() {
+ throw;
+}// { dg-error "not a constant-expression" }
+
+constexpr int fun(int n) {
+ switch (n) {
+ case 0:
+ return 1;
+ default:
+ throw; // { dg-error "not a constant-expression" }
+ }
+}
+
+static_assert(fun(0), "");
+static_assert(fun(1), ""); // { dg-error "non-constant" }
--
Markus
