diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index 5e0fe93ebc0..03a49c59933 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -2160,7 +2160,33 @@ modifying_const_object_error (tree expr, tree obj)
   auto_diagnostic_group d;
   error_at (loc, "modifying a const object %qE is not allowed in "
 	    "a constant expression", TREE_OPERAND (expr, 0));
-  inform (location_of (obj), "originally declared %<const%> here");
+
+  /* Find the underlying object that was declared as const.  */
+  location_t decl_loc = UNKNOWN_LOCATION;
+  for (tree probe = obj; decl_loc == UNKNOWN_LOCATION; )
+    switch (TREE_CODE (probe))
+      {
+      case BIT_FIELD_REF:
+      case COMPONENT_REF:
+	{
+	  tree elt = TREE_OPERAND (probe, 1);
+	  if (CP_TYPE_CONST_P (TREE_TYPE (elt)))
+	    decl_loc = DECL_SOURCE_LOCATION (elt);
+	  probe = TREE_OPERAND (probe, 0);
+	}
+	break;
+
+      case ARRAY_REF:
+      case REALPART_EXPR:
+      case IMAGPART_EXPR:
+	probe = TREE_OPERAND (probe, 0);
+	break;
+
+      default:
+	decl_loc = location_of (probe);
+	break;
+      }
+  inform (decl_loc, "originally declared %<const%> here");
 }
 
 /* Return true if FNDECL is a replaceable global allocation function that
@@ -6959,7 +6985,10 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx, tree t,
       return t;
     }
 
+  /* Change the input location to the currently processed expression for
+     better error messages when a subexpression has no location.  */
   location_t loc = cp_expr_loc_or_input_loc (t);
+  iloc_sentinel sentinel (loc);
 
   STRIP_ANY_LOCATION_WRAPPER (t);
 
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-48089.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-48089.C
index 4574eb83ff7..11630f26ffe 100644
--- a/gcc/testsuite/g++.dg/cpp0x/constexpr-48089.C
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-48089.C
@@ -10,11 +10,11 @@
 // R() is well-formed because i is initialized before j.
 
 struct s {
-  constexpr s() : v(v) { }
+  constexpr s() : v(v) { } // { dg-error "accessing uninitialized member" }
   int v;
 };
 
-constexpr s bang;		// { dg-error "|" }
+constexpr s bang;  // { dg-message "in .constexpr. expansion" }
 
 struct R {
   int i,j;
@@ -26,14 +26,14 @@ constexpr R r;			// { dg-bogus "" }
 // Ill-formed (no diagnostic required)
 struct T {
   int i;
-  constexpr int f() { return i; }
+  constexpr int f() { return i; }  // { dg-error "accessing uninitialized member" }
   constexpr T(): i(0) { }
-  constexpr T(const T& t) : i(f()) { } // { dg-message "" }
+  constexpr T(const T& t) : i(f()) { }  // { dg-message "in .constexpr. expansion" }
 };
 
 constexpr T t1;
 // Ill-formed (diagnostic required)
-constexpr T t2(t1);		// { dg-message "" }
+constexpr T t2(t1);		// { dg-message "in .constexpr. expansion" }
 
 // Well-formed
 struct U {
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-70323.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-70323.C
index 272a225d967..bfb185f2fb5 100644
--- a/gcc/testsuite/g++.dg/cpp0x/constexpr-70323.C
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-70323.C
@@ -1,10 +1,10 @@
 // PR c++/70323
 // { dg-do compile { target c++11 } }
 
-constexpr int overflow_if_0 (int i) { return __INT_MAX__ + !i; }
-constexpr int overflow_if_1 (int i) { return __INT_MAX__ + i; }
+constexpr int overflow_if_0 (int i) { return __INT_MAX__ + !i; }  // { dg-error "overflow in constant expression" }
+constexpr int overflow_if_1 (int i) { return __INT_MAX__ + i; }   // { dg-error "overflow in constant expression" }
 
-constexpr bool i0_0 = overflow_if_0 (0);   // { dg-error "overflow in constant expression|in .constexpr. expansion of " }
+constexpr bool i0_0 = overflow_if_0 (0);   // { dg-message "in .constexpr. expansion of " }
 constexpr bool i0_1 = overflow_if_0 (1);
 constexpr bool i1_0 = overflow_if_1 (0);
-constexpr bool i1_1 = overflow_if_1 (1);   // { dg-error "overflow in constant expression|in .constexpr. expansion of " }
+constexpr bool i1_1 = overflow_if_1 (1);   // { dg-message "in .constexpr. expansion of " }
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-70323a.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-70323a.C
index 1990ab6be2d..b5ed581e1c8 100644
--- a/gcc/testsuite/g++.dg/cpp0x/constexpr-70323a.C
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-70323a.C
@@ -2,10 +2,10 @@
 // { dg-do compile { target c++11 } }
 // { dg-options "-Wall" }
 
-constexpr int overflow_if_0 (int i) { return __INT_MAX__ + !i; }
-constexpr int overflow_if_1 (int i) { return __INT_MAX__ + i; }
+constexpr int overflow_if_0 (int i) { return __INT_MAX__ + !i; }  // { dg-error "overflow in constant expression" }
+constexpr int overflow_if_1 (int i) { return __INT_MAX__ + i; }   // { dg-error "overflow in constant expression" }
 
-constexpr bool i0_0 = overflow_if_0 (0);   // { dg-error "overflow in constant expression|in .constexpr. expansion of" }
+constexpr bool i0_0 = overflow_if_0 (0);   // { dg-message "in .constexpr. expansion of" }
 constexpr bool i0_1 = overflow_if_0 (1);
 constexpr bool i1_0 = overflow_if_1 (0);
-constexpr bool i1_1 = overflow_if_1 (1);   // { dg-error "overflow in constant expression|in .constexpr. expansion of" }
+constexpr bool i1_1 = overflow_if_1 (1);   // { dg-message "in .constexpr. expansion of" }
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-delete2.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-delete2.C
index 999f9b7851e..f2b6df2509c 100644
--- a/gcc/testsuite/g++.dg/cpp0x/constexpr-delete2.C
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-delete2.C
@@ -6,8 +6,9 @@ constexpr int f(int i) { return i; }
 constexpr int g(A* ap)
 {
   return f((delete[] ap, 42)); // { dg-message "" "" { target c++17_down } }
+                               // { dg-error "" "" { target c++2a } .-1 }
 }
 
 A a;
-constexpr int i = g(&a);	// { dg-error "" }
-				// { dg-message "in 'constexpr' expansion of" "" { target c++2a } .-1 }
+constexpr int i = g(&a);  // { dg-error "" "" { target c++17_down } }
+			  // { dg-message "in 'constexpr' expansion of" "" { target c++2a } .-1 }
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-diag3.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-diag3.C
index 5eedf42ba36..50c676c56cd 100644
--- a/gcc/testsuite/g++.dg/cpp0x/constexpr-diag3.C
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-diag3.C
@@ -16,7 +16,7 @@ int main()
 struct complex 			// { dg-message "no .constexpr. constructor" "" { target { ! implicit_constexpr } } }
 {
   complex(double r, double i) : re(r), im(i) { }
-  constexpr double real() const { return re; } // { dg-error "not a literal type" "" { target c++11_only } }
+  constexpr double real() const { return re; } // { dg-error "not a literal type|not usable in a constant expression" "" { target { ! implicit_constexpr } } }
   double imag() const { return im; }
 
 private:
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-ice20.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-ice20.C
index e2d4853a284..43fa9a03c14 100644
--- a/gcc/testsuite/g++.dg/cpp0x/constexpr-ice20.C
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-ice20.C
@@ -3,5 +3,6 @@
 
 typedef bool (*Function)(int);
 constexpr bool check(int x, Function p) { return p(x); }  // { dg-message "in .constexpr. expansion of" }
+// { dg-error "not a constant expression" "" { target *-*-* } .-1 }
 
 static_assert(check(2, check), "");  // { dg-error "conversion|constant|in .constexpr. expansion of" }
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-mutable3.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-mutable3.C
index 51499fac520..bdb2677a350 100644
--- a/gcc/testsuite/g++.dg/cpp0x/constexpr-mutable3.C
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-mutable3.C
@@ -4,6 +4,7 @@
 struct A { mutable int m; };
 
 constexpr int f(A a) { return a.m; }
+// { dg-error "mutable" "" { target c++11_only } .-1 }
 
 static_assert(f({42}) == 42, "");
-// { dg-error "non-constant|mutable" "" { target c++11_only } .-1 }
+// { dg-error "non-constant" "" { target c++11_only } .-1 }
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-recursion.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-recursion.C
index 8c4201e1ec2..b00f8794d4c 100644
--- a/gcc/testsuite/g++.dg/cpp0x/constexpr-recursion.C
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-recursion.C
@@ -1,6 +1,6 @@
 // Test that we catch excessive recursion.
 // { dg-do compile { target c++11 } }
 // { dg-options "-fconstexpr-depth=5" }
-// { dg-prune-output "in constexpr expansion" }
-constexpr int f (int i) { return f (i-1); } // { dg-message "in .constexpr. expansion of " }
-constexpr int i = f(42);	// { dg-error ".constexpr. evaluation depth|in .constexpr. expansion of " }
+// { dg-prune-output "in .constexpr. expansion" }
+constexpr int f (int i) { return f (i-1); } // { dg-error ".constexpr. evaluation depth" }
+constexpr int i = f(42);	
diff --git a/gcc/testsuite/g++.dg/cpp0x/overflow1.C b/gcc/testsuite/g++.dg/cpp0x/overflow1.C
index b8591b4af41..e295355c88f 100644
--- a/gcc/testsuite/g++.dg/cpp0x/overflow1.C
+++ b/gcc/testsuite/g++.dg/cpp0x/overflow1.C
@@ -4,7 +4,7 @@ template <long long i>
 struct Fib
 {
     static const long long value // { dg-error "overflow" }
-    = Fib<i-1>::value + Fib<i-2>::value;
+    = Fib<i-1>::value + Fib<i-2>::value; // { dg-error "overflow" }
 };
 
 template <>
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-89285.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-89285.C
index fe0b8570ca2..efbf9bd15dd 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-89285.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-89285.C
@@ -13,8 +13,9 @@ struct B {
     *c = reinterpret_cast<char *>(this) - reinterpret_cast<char *>(c);	// { dg-error "reinterpret_cast" "" { target c++20_down } }
   }
 };
-struct C : A {
+struct C : A {  // { dg-error "" "" { target c++14_down } }
   B bar {this};
 };
 
-constexpr C foo {};		// { dg-message "" }
+// error path changes in C++17 due to `C` becoming an aggregate
+constexpr C foo {};  // { dg-error "" "" { target c++17 } }
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-89481.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-89481.C
index 8ac4ef0fd36..6f8f6a8038e 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-89481.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-89481.C
@@ -6,7 +6,7 @@ foo ()
 {
   union U { long long a; int b[2]; } u { 5LL };
   u.b[1] = 4;		// { dg-error "change of the active member of a union from" "" { target c++17_down } }
-  return u.b[0];
+  return u.b[0];	// { dg-error "accessing uninitialized array element" "" { target c++2a } }
 }
 
 constexpr int
@@ -19,6 +19,5 @@ bar ()
 
 static_assert (foo () == 0, "");	// { dg-error "non-constant condition for static assertion" }
 					// { dg-message "in 'constexpr' expansion of" "" { target *-*-* } .-1 }
-					// { dg-error "accessing uninitialized array element" "" { target c++2a } .-2 }
 static_assert (bar () == 4, "");	// { dg-error "non-constant condition for static assertion" "" { target c++17_down } }
 					// { dg-message "in 'constexpr' expansion of" "" { target c++17_down } .-1 }
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const14.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const14.C
index 45c4fcf50be..0c77dd4934d 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const14.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const14.C
@@ -14,7 +14,7 @@ struct C {
 
 struct A {
   int r;
-  const C c;
+  const C c; // { dg-message "originally declared" }
   constexpr A() : r(11) { r = 14; const_cast<C &>(c).n = 42; } // { dg-error "modifying a const object" }
 };
 
@@ -34,5 +34,4 @@ struct B {
 };
 
 constexpr B b(false); // { dg-message "in .constexpr. expansion of" }
-// { dg-message "originally declared" "" { target *-*-* } .-1 }
 static_assert(b.e.d.a.c.n == 2, ""); // { dg-error "non-constant condition" }
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const16.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const16.C
index 5a5b92bc8cc..b5ccf3a4ea5 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const16.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const16.C
@@ -7,7 +7,7 @@ constexpr int& impl(const int (&array)[10], int index) {
 
 struct A {
   constexpr int& operator[](int i) { return impl(elems, i); }
-  const int elems[10];
+  const int elems[10]; // { dg-message "originally declared" }
 };
 
 constexpr bool
@@ -19,4 +19,3 @@ f()
 }
 
 constexpr bool b = f(); // { dg-message "in .constexpr. expansion of " }
-// { dg-message "originally declared" "" { target *-*-* } .-1 }
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const18.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const18.C
index 11a680468c2..278628c121b 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const18.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const18.C
@@ -13,11 +13,11 @@ struct array
 template <typename T>
 struct S {
   using U = array<T, 4>;
-  const U m;
+  const U m; // { dg-message "originally declared" }
   constexpr S(int) : m{}
   {
     const_cast<int &>(const_cast<const U &>(m)[0]) = 42; // { dg-error "modifying a const object" }
   }
 };
 
-constexpr S<int> p = { 10 }; // { dg-message "originally declared" }
+constexpr S<int> p = { 10 };
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const19.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const19.C
index c31222ffcdd..2d18c94537b 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const19.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const19.C
@@ -7,7 +7,7 @@ template <typename E, size_t N>
 struct array
 {
   constexpr const E &operator[](size_t n) const noexcept { return elems[n]; }
-  const E elems[N];
+  const E elems[N]; // { dg-message "originally declared" }
 };
 
 template <typename T>
@@ -20,4 +20,4 @@ struct S {
   }
 };
 
-constexpr S<int> p = { 10 }; // { dg-message "originally declared" }
+constexpr S<int> p = { 10 };
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const21.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const21.C
index 0b16193398e..d3bbcb116a6 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const21.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const21.C
@@ -18,11 +18,11 @@ struct array2 {
 template <typename T>
 struct S {
   using U = array2<T, 4>;
-  const U m;
+  const U m; // { dg-message "originally declared" }
   constexpr S(int) : m{}
   {
     const_cast<int &>(m.a[0]) = 42; // { dg-error "modifying a const object" }
   }
 };
 
-constexpr S<int> p = { 10 }; // { dg-message "originally declared" }
+constexpr S<int> p = { 10 };
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const22.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const22.C
index 216cf1607a4..27522f86dbd 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const22.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const22.C
@@ -7,11 +7,11 @@ struct X {
 
 template <typename T>
 struct S {
-  const X x;
+  const X x; // { dg-message "originally declared" }
   constexpr S(int) : x{}
   {
     const_cast<X&>(x).i = 19; // { dg-error "modifying a const object" }
   }
 };
 
-constexpr S<int> p = { 10 }; // { dg-message "originally declared" }
+constexpr S<int> p = { 10 };
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const3.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const3.C
index 6853775c1e2..fc88dd05eef 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const3.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const3.C
@@ -7,7 +7,7 @@ struct A {
 };
 
 struct B {
-  const A a;
+  const A a; // { dg-message "originally declared" }
   constexpr B(bool b) {
     if (b)
       const_cast<A &>(a).n = 3; // { dg-error "modifying a const object" }
@@ -18,5 +18,4 @@ constexpr B b(false);
 static_assert(b.a.n == 2, "");
 
 constexpr B b2(true); // { dg-message "in .constexpr. expansion of " }
-// { dg-message "originally declared" "" { target *-*-* } .-1 } 
 static_assert((b2.a.n, 1), "");
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const4.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const4.C
index 8263a7cc505..27fede152c7 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const4.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const4.C
@@ -2,7 +2,7 @@
 // { dg-do compile { target c++14 } }
 
 struct A {
-  const int n;
+  const int n; // { dg-message "originally declared" }
   constexpr A() : n(1) { }
 };
 struct B {
@@ -13,5 +13,4 @@ struct B {
   }
 };
 constexpr B b; // { dg-message "in .constexpr. expansion of " }
-// { dg-message "originally declared" "" { target *-*-* } .-1 }
 static_assert((b.a.n, 1), "");
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const7.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const7.C
index 922e8ff126f..bea14b05602 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const7.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const7.C
@@ -3,7 +3,7 @@
 
 struct D { int n; };
 
-struct C { const D d; };
+struct C { const D d; }; // { dg-message "originally declared" }
 
 struct A {
   C c;
@@ -19,5 +19,4 @@ struct B {
 };
 
 constexpr B b{}; // { dg-message "in .constexpr. expansion of " }
-// { dg-message "originally declared" "" { target *-*-* } .-1 }
 static_assert((b.a.c.d.n, 1), "");
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-union5.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-union5.C
index 55fe9fa2f0b..3d76345d564 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-union5.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-union5.C
@@ -8,8 +8,8 @@ union U {
 };
 
 constexpr int foo(U *up) {
-  up->a++;
+  up->a++; // { dg-error "accessing uninitialized member" }
   return {42};
 }
 
-extern constexpr U u = {}; // { dg-error "accessing uninitialized member" }
+extern constexpr U u = {}; // { dg-message "in .constexpr. expansion" }
diff --git a/gcc/testsuite/g++.dg/cpp1y/pr68180.C b/gcc/testsuite/g++.dg/cpp1y/pr68180.C
index 9e6e5e984f9..8de1ef3936b 100644
--- a/gcc/testsuite/g++.dg/cpp1y/pr68180.C
+++ b/gcc/testsuite/g++.dg/cpp1y/pr68180.C
@@ -6,11 +6,11 @@ typedef float __attribute__( ( vector_size( 16 ) ) ) float32x4_t;
 constexpr float32x4_t fill(float x) {
   float32x4_t v{0};
   constexpr auto vs = sizeof(v)/sizeof(v[0]);
-  for (auto i=0U; i<vs; ++i) v[i]=i;
+  for (auto i=0U; i<vs; ++i) v[i]=i; // { dg-error "not a constant" }
   return v+x;
 }
 
 float32x4_t foo(float32x4_t x) {
-  constexpr float32x4_t v = fill(1.f); // { dg-error "not a constant||in .constexpr. expansion of " }
+  constexpr float32x4_t v = fill(1.f); // { dg-message "in .constexpr. expansion of " }
   return x+v;
 }
diff --git a/gcc/testsuite/g++.dg/cpp1z/constexpr-lambda6.C b/gcc/testsuite/g++.dg/cpp1z/constexpr-lambda6.C
index 214d3821299..c46c2d4c7fe 100644
--- a/gcc/testsuite/g++.dg/cpp1z/constexpr-lambda6.C
+++ b/gcc/testsuite/g++.dg/cpp1z/constexpr-lambda6.C
@@ -1,7 +1,7 @@
 // Testcase from P0170R1
 // { dg-do compile { target c++17 } }
 
-auto monoid = [](auto v) { return [=] { return v; }; };
+auto monoid = [](auto v) { return [=] { return v; }; };  // { dg-error "not usable in a constant expression" }
 auto add = [](auto m1) constexpr {
   auto ret = m1();
   return [=](auto m2) mutable {
@@ -22,7 +22,7 @@ int main()
   // member function call operator can not perform an lvalue-to-rvalue conversion
   // on one of its subobjects (that represents its capture) in a constant
   // expression.
-  auto two = monoid(2);
+  auto two = monoid(2);  // { dg-message "not declared .constexpr." }
   if (!(two() == 2)) __builtin_abort(); // OK, not a constant expression.
   static_assert(add(one)(one)() == two()); // { dg-error "|in .constexpr. expansion of " } two() is not a constant expression
   static_assert(add(one)(one)() == monoid(2)()); // OK
diff --git a/gcc/testsuite/g++.dg/cpp1z/constexpr-lambda8.C b/gcc/testsuite/g++.dg/cpp1z/constexpr-lambda8.C
index 84be68ab7f0..82351ff0c54 100644
--- a/gcc/testsuite/g++.dg/cpp1z/constexpr-lambda8.C
+++ b/gcc/testsuite/g++.dg/cpp1z/constexpr-lambda8.C
@@ -4,11 +4,14 @@
 auto Fwd = [](int (*fp)(int), auto a) { return fp(a); };
 auto C = [](auto a) { return a; };
 static_assert( Fwd(C ,3) == 3); // OK
+
 // No specialization of the function call operator template can be constexpr
 // (because of the local static).
 auto NC = [](auto a) { static int s; return a; }; // { dg-error "static" }
-// { dg-message "operator int" "" { target *-*-* } .+1 }
+// { dg-error "called in a constant expression" "" { target *-*-* } .-1 }
+
 static_assert( Fwd(NC ,3) == 3); // { dg-error "" }
+// { dg-message "operator int" "" { target *-*-* } .-1 }
 
 // We look for the string "operator int" to check that we aren't trying to do
 // template pretty-printing in an expression; that gets incredibly unwieldy
diff --git a/gcc/testsuite/g++.dg/cpp2a/bit-cast11.C b/gcc/testsuite/g++.dg/cpp2a/bit-cast11.C
index a3eb31bc6c7..760c9ca40b4 100644
--- a/gcc/testsuite/g++.dg/cpp2a/bit-cast11.C
+++ b/gcc/testsuite/g++.dg/cpp2a/bit-cast11.C
@@ -28,7 +28,7 @@ f3 ()
 {
   T t = { 1, 2 };
   S s = __builtin_bit_cast (S, t);
-  return s.a[1] == 0;
+  return s.a[1] == 0;		// { dg-error "accessing uninitialized array element" }
 }
 
 constexpr bool
@@ -52,12 +52,12 @@ f6 ()
 {
   W t = { 1, 2 };
   V s = __builtin_bit_cast (V, t);
-  return s.b.a[1] == 1;
+  return s.b.a[1] == 1;		// { dg-error "accessing uninitialized array element" }
 }
 
 constexpr bool a = f1 ();
 constexpr bool b = f2 ();
-constexpr bool c = f3 ();	// { dg-error "accessing uninitialized array element" }
-constexpr bool d = f4 ();
+constexpr bool c = f3 ();	// { dg-message "in .constexpr. expansion" }
+constexpr bool d = f4 ();	// { dg-message "in .constexpr. expansion" }
 constexpr bool e = f5 ();
-constexpr bool f = f6 ();	// { dg-error "accessing uninitialized array element" }
+constexpr bool f = f6 ();	// { dg-message "in .constexpr. expansion" }
diff --git a/gcc/testsuite/g++.dg/cpp2a/bit-cast12.C b/gcc/testsuite/g++.dg/cpp2a/bit-cast12.C
index 9c699dd55f0..e205bc6a8c1 100644
--- a/gcc/testsuite/g++.dg/cpp2a/bit-cast12.C
+++ b/gcc/testsuite/g++.dg/cpp2a/bit-cast12.C
@@ -33,7 +33,7 @@ f3 ()
 {
   T t = { 1, 2 };
   S s = __builtin_bit_cast (S, t);
-  return s.a[1] == 0;
+  return s.a[1] == 0;		// { dg-error "accessing uninitialized array element" }
 }
 
 constexpr bool
@@ -57,12 +57,12 @@ f6 ()
 {
   W t = { 1, 2 };
   V s = __builtin_bit_cast (V, t);
-  return s.b.a[1] == 1;
+  return s.b.a[1] == 1;		// { dg-error "accessing uninitialized array element" }
 }
 
 constexpr bool a = f1 ();
 constexpr bool b = f2 ();
-constexpr bool c = f3 ();	// { dg-error "accessing uninitialized array element" }
-constexpr bool d = f4 ();
+constexpr bool c = f3 ();	// { dg-message "in .constexpr. expansion" }
+constexpr bool d = f4 ();	// { dg-message "in .constexpr. expansion" }
 constexpr bool e = f5 ();
-constexpr bool f = f6 ();	// { dg-error "accessing uninitialized array element" }
+constexpr bool f = f6 ();	// { dg-message "in .constexpr. expansion" }
diff --git a/gcc/testsuite/g++.dg/cpp2a/bit-cast14.C b/gcc/testsuite/g++.dg/cpp2a/bit-cast14.C
index 5e185919be4..e0cc9a39702 100644
--- a/gcc/testsuite/g++.dg/cpp2a/bit-cast14.C
+++ b/gcc/testsuite/g++.dg/cpp2a/bit-cast14.C
@@ -44,7 +44,7 @@ f5 ()
 {
   T1 t = { 0, 0, 0, 0, 0, 0, 0 };
   S s = __builtin_bit_cast (S, t);
-  unsigned char a = s.a;
+  unsigned char a = s.a;		// { dg-error "accessing uninitialized member" }
   return true;
 }
 
@@ -53,7 +53,7 @@ f6 ()
 {
   T2 t = { 0, 0, 0, 0, 0, 0, 0 };
   S s = __builtin_bit_cast (S, t);
-  unsigned char b = s.b;
+  unsigned char b = s.b;		// { dg-error "accessing uninitialized member" }
   return true;
 }
 
@@ -62,14 +62,14 @@ f7 ()
 {
   T3 t = { 0, 0, 0, 0, 0, 0, 0 };
   S s = __builtin_bit_cast (S, t);
-  unsigned char c = s.c;
+  unsigned char c = s.c;		// { dg-error "accessing uninitialized member" }
   return true;
 }
 
 constexpr bool a = f1 ();
 constexpr bool b = f2 ();
 constexpr bool c = f3 ();
-constexpr bool d = f4 ();
-constexpr bool e = f5 ();	// { dg-error "accessing uninitialized member" }
-constexpr bool f = f6 ();	// { dg-error "accessing uninitialized member" }
-constexpr bool g = f7 ();	// { dg-error "accessing uninitialized member" }
+constexpr bool d = f4 ();	// { dg-message "in .constexpr. expansion" }
+constexpr bool e = f5 ();	// { dg-message "in .constexpr. expansion" }
+constexpr bool f = f6 ();	// { dg-message "in .constexpr. expansion" }
+constexpr bool g = f7 ();	// { dg-message "in .constexpr. expansion" }
diff --git a/gcc/testsuite/g++.dg/cpp2a/constexpr-98122.C b/gcc/testsuite/g++.dg/cpp2a/constexpr-98122.C
index 01bdfa5bd4d..b0c91d5ef97 100644
--- a/gcc/testsuite/g++.dg/cpp2a/constexpr-98122.C
+++ b/gcc/testsuite/g++.dg/cpp2a/constexpr-98122.C
@@ -9,7 +9,7 @@ bar ()
 {
   V f { .b = 42 };
   constexpr auto m = &V::a;
-  return (f.*m) == 42;
+  return (f.*m) == 42;  // { dg-error "accessing 'V::a' member instead of initialized 'V::b' member in constant expression" }
 }
 
 constexpr bool
@@ -21,5 +21,5 @@ baz ()
 }
 
 static_assert (bar (), "");	// { dg-error "non-constant condition for static assertion" }
-				// { dg-error "accessing 'V::a' member instead of initialized 'V::b' member in constant expression" "" { target *-*-* } .-1 }
+				// { dg-message "in .constexpr. expansion" "" { target *-*-* } .-1 }
 static_assert (baz (), "");
diff --git a/gcc/testsuite/g++.dg/cpp2a/constexpr-dynamic17.C b/gcc/testsuite/g++.dg/cpp2a/constexpr-dynamic17.C
index a26678e6ed7..28facf192df 100644
--- a/gcc/testsuite/g++.dg/cpp2a/constexpr-dynamic17.C
+++ b/gcc/testsuite/g++.dg/cpp2a/constexpr-dynamic17.C
@@ -25,8 +25,7 @@ struct D : B, A {
 
 constexpr B::B(V* v, A* a)
 {
-  dynamic_cast<B*>(a);
+  dynamic_cast<B*>(a); // { dg-error "accessing uninitialized member" }
 }
 
-constexpr D d; // { dg-error "accessing uninitialized member" }
-// { dg-message "in 'constexpr' expansion of" "" { target *-*-* } .-1 }
+constexpr D d; // { dg-message "in 'constexpr' expansion of" }
diff --git a/gcc/testsuite/g++.dg/cpp2a/constexpr-init1.C b/gcc/testsuite/g++.dg/cpp2a/constexpr-init1.C
index e56ecfed48a..b4e39b6f928 100644
--- a/gcc/testsuite/g++.dg/cpp2a/constexpr-init1.C
+++ b/gcc/testsuite/g++.dg/cpp2a/constexpr-init1.C
@@ -52,11 +52,10 @@ constexpr int
 fn5 ()
 {
   struct S { int a = 9; int b; } s;
-  return s.b;
+  return s.b; // { dg-error "accessing uninitialized member" }
 }
 
-constexpr int b = fn5 (); // { dg-error "accessing uninitialized member" }
-// { dg-message "in .constexpr. expansion of" "" { target *-*-* } .-1 }
+constexpr int b = fn5 (); // { dg-message "in .constexpr. expansion of" }
 
 constexpr int
 fn6 ()
diff --git a/gcc/testsuite/g++.dg/cpp2a/constexpr-new12.C b/gcc/testsuite/g++.dg/cpp2a/constexpr-new12.C
index 5a3d06a5fab..832782e1427 100644
--- a/gcc/testsuite/g++.dg/cpp2a/constexpr-new12.C
+++ b/gcc/testsuite/g++.dg/cpp2a/constexpr-new12.C
@@ -17,11 +17,11 @@ struct B : A {
 constexpr int
 foo ()
 {
-  A *a = new B ();
+  A *a = new B ();  // { dg-message "allocated here" }
   a->a = 4;
   delete a;
-  int r = a->foo ();
+  int r = a->foo ();  // { dg-error "constant expression" }
   return r;
 }
 
-constexpr auto a = foo ();	// { dg-error "constant expression" }
+constexpr auto a = foo ();  // { dg-message "in .constexpr. expansion" }
diff --git a/gcc/testsuite/g++.dg/cpp2a/constexpr-new3.C b/gcc/testsuite/g++.dg/cpp2a/constexpr-new3.C
index 70b841208f8..3ba440fec53 100644
--- a/gcc/testsuite/g++.dg/cpp2a/constexpr-new3.C
+++ b/gcc/testsuite/g++.dg/cpp2a/constexpr-new3.C
@@ -45,11 +45,10 @@ constexpr bool
 f5 ()
 {
   int *p = new int;		// { dg-message "allocated here" }
-  return *p == 1;
+  return *p == 1;		// { dg-error "the content of uninitialized storage is not usable in a constant expression" }
 }
 
-constexpr auto v5 = f5 ();	// { dg-error "the content of uninitialized storage is not usable in a constant expression" }
-				// { dg-message "in 'constexpr' expansion of" "" { target *-*-* } .-1 }
+constexpr auto v5 = f5 (); 	// { dg-message "in 'constexpr' expansion of" }
 
 constexpr bool
 f6 ()
@@ -57,11 +56,10 @@ f6 ()
   int *p = new int (2);		// { dg-message "allocated here" }
   int *q = p;
   delete p;
-  return *q == 2;
+  return *q == 2;		// { dg-error "use of allocated storage after deallocation in a constant expression" }
 }
 
-constexpr auto v6 = f6 ();	// { dg-error "use of allocated storage after deallocation in a constant expression" }
-				// { dg-message "in 'constexpr' expansion of" "" { target *-*-* } .-1  }
+constexpr auto v6 = f6 (); 	// { dg-message "in 'constexpr' expansion of" }
 
 constexpr int *
 f7 ()
diff --git a/gcc/testsuite/g++.dg/cpp2a/constinit10.C b/gcc/testsuite/g++.dg/cpp2a/constinit10.C
index b678788541e..d2c49c41f91 100644
--- a/gcc/testsuite/g++.dg/cpp2a/constinit10.C
+++ b/gcc/testsuite/g++.dg/cpp2a/constinit10.C
@@ -11,15 +11,14 @@ struct S1
 struct alignas(64) S2
 {
     constexpr S2 ()
-    : m_tabS1()
+    : m_tabS1() // { dg-error "used before its definition" }
     {}
 
     S1 m_tabS1[7];
 };
 
 constinit S2 objX; // { dg-error ".constinit. variable .objX. does not have a constant initializer" }
-// { dg-error "used before its definition" "" { target *-*-* } .-1 }
-// // { dg-message "in .constexpr. expansion of" "" { target *-*-* } .-2 }
+// { dg-message "in .constexpr. expansion of" "" { target *-*-* } .-1 }
 
 constexpr S1::S1 ()
 : m_i(14)
diff --git a/gcc/testsuite/g++.dg/cpp2a/is-corresponding-member4.C b/gcc/testsuite/g++.dg/cpp2a/is-corresponding-member4.C
index 6b74090306b..241e9976e8c 100644
--- a/gcc/testsuite/g++.dg/cpp2a/is-corresponding-member4.C
+++ b/gcc/testsuite/g++.dg/cpp2a/is-corresponding-member4.C
@@ -14,8 +14,8 @@ is_corresponding_member (M1 S1::*m1, M2 S2::*m2) noexcept
 struct A { int a; };
 struct B;
 constexpr int B::*n = nullptr;
-constexpr auto a = std::is_corresponding_member (&A::a, n);	// { dg-error "invalid use of incomplete type 'struct B'" }
-constexpr auto b = std::is_corresponding_member (n, &A::a);	// { dg-error "invalid use of incomplete type 'struct B'" }
+constexpr auto a = std::is_corresponding_member (&A::a, n);	// { dg-message "in .constexpr. expansion of" }
+constexpr auto b = std::is_corresponding_member (n, &A::a);	// { dg-message "in .constexpr. expansion of" }
 
 void
 foo (int B::*m)
diff --git a/gcc/testsuite/g++.dg/ext/constexpr-vla2.C b/gcc/testsuite/g++.dg/ext/constexpr-vla2.C
index d4ea7c58c0d..e09a27af3de 100644
--- a/gcc/testsuite/g++.dg/ext/constexpr-vla2.C
+++ b/gcc/testsuite/g++.dg/ext/constexpr-vla2.C
@@ -4,7 +4,7 @@
 constexpr int
 fn_bad (int n)
 {
-  __extension__ int a [n] = { 0 };
+  __extension__ int a [n] = { 0 };  // { dg-error "array subscript" }
   int z = a [0] + (n ? fn_bad (n - 1) : 0); // { dg-message "in .constexpr. expansion of " } 
   return z;
 }
@@ -18,4 +18,4 @@ fn_ok (int n)
 }
 
 constexpr int i1 = fn_ok (3);
-constexpr int i2 = fn_bad (3); // { dg-error "array subscript|in .constexpr. expansion of " }
+constexpr int i2 = fn_bad (3); // { dg-message "in .constexpr. expansion of " }
diff --git a/gcc/testsuite/g++.dg/ext/constexpr-vla3.C b/gcc/testsuite/g++.dg/ext/constexpr-vla3.C
index 538b576a825..6f9daa1897f 100644
--- a/gcc/testsuite/g++.dg/ext/constexpr-vla3.C
+++ b/gcc/testsuite/g++.dg/ext/constexpr-vla3.C
@@ -4,11 +4,11 @@
 constexpr int
 foo (int n)
 {
-  __extension__ int a[n] = { 1, 2, 3, 4, 5, 6 };
+  __extension__ int a[n] = { 1, 2, 3, 4, 5, 6 }; // { dg-error "array subscript" }
   int z = 0;
   for (int i = 0; i <= n; ++i)
     z += a[i];
   return z;
 }
 
-constexpr int n = foo (3); // { dg-error "array subscript|in .constexpr. expansion of " }
+constexpr int n = foo (3); // { dg-message "in .constexpr. expansion of " }
diff --git a/gcc/testsuite/g++.dg/ubsan/pr63956.C b/gcc/testsuite/g++.dg/ubsan/pr63956.C
index 3a1596e6e2e..6fd0b4f893e 100644
--- a/gcc/testsuite/g++.dg/ubsan/pr63956.C
+++ b/gcc/testsuite/g++.dg/ubsan/pr63956.C
@@ -56,12 +56,13 @@ fn3 (int a, int b)
 {
   if (b != 2)
     a = a / b; // { dg-error "..7 / 0.. is not a constant expression" }
+               // { dg-error "overflow in constant expression" "" { target *-*-* } .-1 }
   return a;
 }
 
 constexpr int k1 = fn3 (8, 4);
 constexpr int k2 = fn3 (7, 0); // { dg-message "in .constexpr. expansion" }
-constexpr int k3 = fn3 (INT_MIN, -1); // { dg-error "overflow in constant expression|in .constexpr. expansion of " }
+constexpr int k3 = fn3 (INT_MIN, -1); // { dg-message "in .constexpr. expansion of " }
 
 SA (k1 == 2);
 
@@ -100,13 +101,13 @@ constexpr int
 fn7 (const int *a, int b)
 {
   if (b != 3)
-    return fn6 (*a, b);
+    return fn6 (*a, b); // { dg-error "null pointer" }
   return 7;
 }
 
 constexpr int n1 = 7;
 constexpr int n2 = fn7 (&n1, 5);
-constexpr int n3 = fn7 ((const int *) 0, 8);  // { dg-error "null pointer|in .constexpr. expansion of " }
+constexpr int n3 = fn7 ((const int *) 0, 8);  // { dg-message "in .constexpr. expansion of " }
 
 constexpr int
 fn8 (int i)
@@ -122,15 +123,15 @@ constexpr int
 fn9 (int a, int b)
 {
   if (b != 0)
-    return a + b;
+    return a + b; // { dg-error "overflow in constant expression" }
   return a;
 }
 
 constexpr int p1 = fn9 (42, 7);
-constexpr int p2 = fn9 (__INT_MAX__, 1); // { dg-error "overflow in constant expression|in .constexpr. expansion of " }
+constexpr int p2 = fn9 (__INT_MAX__, 1); // { dg-message "in .constexpr. expansion of " }
 constexpr int p3 = fn9 (__INT_MAX__, -1);
 constexpr int p4 = fn9 (INT_MIN, 1);
-constexpr int p5 = fn9 (INT_MIN, -1); // { dg-error "overflow in constant expression|in .constexpr. expansion of " }
+constexpr int p5 = fn9 (INT_MIN, -1); // { dg-message "in .constexpr. expansion of " }
 
 SA (p1 == 49);
 SA (p3 == __INT_MAX__ - 1);
@@ -140,13 +141,13 @@ constexpr int
 fn10 (int a, int b)
 {
   if (b != 0)
-    return a * b;
+    return a * b; // { dg-error "overflow in constant expression" }
   return a;
 }
 
 constexpr int q1 = fn10 (10, 10);
-constexpr int q2 = fn10 (__INT_MAX__, 2); // { dg-error "overflow in constant expression|in .constexpr. expansion of " }
-constexpr int q3 = fn10 (INT_MIN, 2); // { dg-error "overflow in constant expression|in .constexpr. expansion of " }
+constexpr int q2 = fn10 (__INT_MAX__, 2); // { dg-message "in .constexpr. expansion of " }
+constexpr int q3 = fn10 (INT_MIN, 2); // { dg-message "in .constexpr. expansion of " }
 constexpr int q4 = fn10 (-1, -1);
 
 SA (q1 == 100);
@@ -155,14 +156,14 @@ SA (q4 == 1);
 constexpr int
 fn11 (double d)
 {
-  int i = d;
+  int i = d; // { dg-error "overflow in constant expression" }
   if (i != 0)
     return i;
   return i * 2;
 }
 
 constexpr int r1 = fn11 (3.4);
-constexpr int r2 = fn11 (__builtin_inf ()); // { dg-error "overflow in constant expression|in .constexpr. expansion of " }
+constexpr int r2 = fn11 (__builtin_inf ()); // { dg-message "in .constexpr. expansion of " }
 
 constexpr int
 fn12 (int i)
diff --git a/libstdc++-v3/testsuite/25_algorithms/equal/constexpr_neg.cc b/libstdc++-v3/testsuite/25_algorithms/equal/constexpr_neg.cc
index 34ca5c4805c..fd89ac0e166 100644
--- a/libstdc++-v3/testsuite/25_algorithms/equal/constexpr_neg.cc
+++ b/libstdc++-v3/testsuite/25_algorithms/equal/constexpr_neg.cc
@@ -32,7 +32,7 @@ test01()
   return outa;
 }
 
-static_assert(test01()); // { dg-error "outside the bounds" }
+static_assert(test01()); // { dg-error "non-constant condition" }
 
 constexpr bool
 test02()
@@ -44,7 +44,8 @@ test02()
   return outa;
 }
 
-static_assert(test02()); // { dg-error "outside the bounds" }
+static_assert(test02()); // { dg-error "non-constant condition" }
 
-// { dg-prune-output "non-constant condition" }
+// Errors occuring within <algorithm> internals:
+// { dg-error "outside the bounds of array" "" { target *-*-* } 0 }
 // { dg-prune-output "in 'constexpr'" }
diff --git a/libstdc++-v3/testsuite/26_numerics/gcd/105844.cc b/libstdc++-v3/testsuite/26_numerics/gcd/105844.cc
index 5b6fea7b560..bc9b29bc39d 100644
--- a/libstdc++-v3/testsuite/26_numerics/gcd/105844.cc
+++ b/libstdc++-v3/testsuite/26_numerics/gcd/105844.cc
@@ -13,9 +13,11 @@ static_assert( std::gcd(LLONG_MIN, 2ull) == 2 );
 static_assert( std::gcd(2ull, LLONG_MIN) == 2 );
 
 // But |INT_MIN| cannot be represented in common_type<int, int> i.e. int.
-constexpr int a = std::gcd(INT_MIN, 1); // { dg-error "overflow" }
-constexpr int b = std::gcd(1, INT_MIN); // { dg-error "overflow" }
+constexpr int a = std::gcd(INT_MIN, 1); // { dg-error "in .constexpr." }
+constexpr int b = std::gcd(1, INT_MIN); // { dg-error "in .constexpr." }
 
 // And |LLONG_MIN| cannot be represented in long.
-constexpr long long c = std::gcd(LLONG_MIN, 1); // { dg-error "overflow" }
-constexpr long long d = std::gcd(1, LLONG_MIN); // { dg-error "overflow" }
+constexpr long long c = std::gcd(LLONG_MIN, 1); // { dg-error "in .constexpr." }
+constexpr long long d = std::gcd(1, LLONG_MIN); // { dg-error "in .constexpr." }
+
+// { dg-error "overflow" "" { target *-*-* } 0 }
diff --git a/libstdc++-v3/testsuite/26_numerics/lcm/105844.cc b/libstdc++-v3/testsuite/26_numerics/lcm/105844.cc
index d0e032e03e0..d853974f77e 100644
--- a/libstdc++-v3/testsuite/26_numerics/lcm/105844.cc
+++ b/libstdc++-v3/testsuite/26_numerics/lcm/105844.cc
@@ -9,14 +9,16 @@ static_assert( std::lcm(INT_MIN, 1u) == INT_MAX+1u );
 static_assert( std::lcm(1u, INT_MIN) == INT_MAX+1u );
 
 // But |INT_MIN| cannot be represented in common_type<int, int> i.e. int.
-constexpr int a = std::lcm(INT_MIN, 1); // { dg-error "overflow" }
-constexpr int b = std::lcm(1, INT_MIN); // { dg-error "overflow" }
+constexpr int a = std::lcm(INT_MIN, 1); // { dg-error "in .constexpr." }
+constexpr int b = std::lcm(1, INT_MIN); // { dg-error "in .constexpr." }
 
 // And the LCM of 50000 and 49999 cannot be represented in int.
-constexpr int c = std::lcm(50000, 49999); // { dg-error "overflow" }
-constexpr int d = std::lcm(49999, 50000); // { dg-error "overflow" }
+constexpr int c = std::lcm(50000, 49999); // { dg-error "in .constexpr." }
+constexpr int d = std::lcm(49999, 50000); // { dg-error "in .constexpr." }
 
 // Similarly for unsigned, but the diagnostic is a failed assertion instead.
-constexpr int e = std::lcm(500000u, 499999); // { dg-error "in 'constexpr'" }
-constexpr int f = std::lcm(499999u, 500000); // { dg-error "in 'constexpr'" }
+constexpr int e = std::lcm(500000u, 499999); // { dg-error "in .constexpr." }
+constexpr int f = std::lcm(499999u, 500000); // { dg-error "in .constexpr." }
+
+// { dg-error "overflow" "" { target *-*-* } 0 }
 // { dg-error "unreachable" "" { target *-*-* } 0 }