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semantics.c (cxx_eval_constant_expression): Explain unacceptable use of variable better.

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* semantics.c (cxx_eval_constant_expression): Explain
	unacceptable use of variable better.

From-SVN: r166168
This commit is contained in:
Jason Merrill 2010-11-01 21:31:31 -04:00 committed by Jason Merrill
parent fa2200cbb1
commit ddbbc9a109
8 changed files with 41 additions and 7 deletions
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5
gcc/cp/ChangeLog
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@ -1,3 +1,8 @@
2010-11-01 Jason Merrill <jason@redhat.com>
* semantics.c (cxx_eval_constant_expression): Explain
unacceptable use of variable better.
2010-11-01 Gabriel Dos Reis <gdr@cse.tamu.edu>
Jason Merrill <jason@redhat.com>

31
gcc/cp/semantics.c
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@ -6513,7 +6513,36 @@ cxx_eval_constant_expression (const constexpr_call *call, tree t,
if (DECL_P (r))
{
if (!allow_non_constant)
error ("%qD cannot appear in a constant expression", r);
{
tree type = TREE_TYPE (r);
error ("the value of %qD is not usable in a constant "
"expression", r);
if (INTEGRAL_OR_ENUMERATION_TYPE_P (type))
{
if (!CP_TYPE_CONST_P (type))
inform (DECL_SOURCE_LOCATION (r),
"%q#D is not const", r);
else if (CP_TYPE_VOLATILE_P (type))
inform (DECL_SOURCE_LOCATION (r),
"%q#D is volatile", r);
else if (!DECL_INITIAL (r))
inform (DECL_SOURCE_LOCATION (r),
"%qD was not initialized with a constant "
"expression", r);
else
gcc_unreachable ();
}
else
{
if (cxx_dialect >= cxx0x && !DECL_DECLARED_CONSTEXPR_P (r))
inform (DECL_SOURCE_LOCATION (r),
"%qD was not declared %<constexpr%>", r);
else
inform (DECL_SOURCE_LOCATION (r),
"%qD does not have integral or enumeration type",
r);
}
}
*non_constant_p = true;
}
break;

2
gcc/testsuite/g++.dg/cpp0x/constexpr-ex1.C
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@ -55,7 +55,7 @@ constexpr complex I(0, 1); // OK -- literal complex
// 2 invoked with non-const args
double x5 = 1.0;
double x5 = 1.0; // { dg-message "not declared .constexpr" }
constexpr complex unit(x5, 0); // { dg-error "x5|argument" } error: x5 non-constant
const complex one(x5, 0); // OK, ‘‘ordinary const’’ -- dynamic
// initialization

2
gcc/testsuite/g++.dg/cpp0x/constexpr-ex3.C
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@ -15,7 +15,7 @@ struct B
constexpr B(T _t): t(_t) { }
};
B<int> b(1);
B<int> b(1); // { dg-message "not declared .constexpr" }
SA(b.t==1); // { dg-error "non-constant condition|'b'" }
constexpr B<int> b2(1);
SA(b2.t==1);

2
gcc/testsuite/g++.dg/cpp0x/constexpr-function2.C
View File

@ -17,7 +17,7 @@ inline constexpr double
squared(double x) { return x * x; }
constexpr int squarei(int x) { return x * x; }
extern const int side;
extern const int side; // { dg-message "not initialized with a constant expression" }
constexpr int area = squarei(side); // { dg-error "side|argument" }
// error: squarei(side) is not a constant expression

2
gcc/testsuite/g++.dg/cpp0x/constexpr-non-const-arg.C
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@ -7,7 +7,7 @@ struct B {
int i;
};
int global; // not constant
int global; // { dg-message "not const" }
struct D : B {
constexpr D() : B(global) { } // { dg-error "global|argument" }

2
gcc/testsuite/g++.dg/parse/constant4.C
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@ -16,7 +16,7 @@ void Foo ()
Y<I> i;
static const unsigned J = X<T>::J;
static const unsigned J = X<T>::J; // { dg-message "not initialized with a constant expression" }
Y<J> j; // { dg-error "constant" "" }
}

2
gcc/testsuite/g++.dg/template/qualified-id3.C
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@ -2,7 +2,7 @@
template <const int N> struct A { };
template <class T> struct B {
static const int c;
static const int c; // { dg-message "not initialized with a constant expression" }
typedef A<B<T>::c> C; // { dg-error "constant expression" }
};
template <class T> const int B<T>::c = sizeof (T);