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Emit CCEDiags when evaluating a const variable. 

This addresses post-review feedback from r290577.

llvm-svn: 290584
This commit is contained in:
George Burgess IV 2016-12-27 05:33:20 +00:00
parent 2da265b7bf
commit b531698ff0
3 changed files with 16 additions and 10 deletions
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5
clang/lib/AST/ExprConstant.cpp
View File

@ -2903,7 +2903,7 @@ static CompleteObject findCompleteObject(EvalInfo &Info, const Expr *E,
// All the remaining cases only permit reading.
Info.FFDiag(E, diag::note_constexpr_modify_global);
return CompleteObject();
} else if (VD->isConstexpr() || BaseType.isConstQualified()) {
} else if (VD->isConstexpr()) {
// OK, we can read this variable.
} else if (BaseType->isIntegralOrEnumerationType()) {
// In OpenCL if a variable is in constant address space it is a const value.
@ -2928,6 +2928,9 @@ static CompleteObject findCompleteObject(EvalInfo &Info, const Expr *E,
} else {
Info.CCEDiag(E);
}
} else if (BaseType.isConstQualified() && VD->hasDefinition(Info.Ctx)) {
Info.CCEDiag(E, diag::note_constexpr_ltor_non_constexpr) << VD;
// Keep evaluating to see what we can do.
} else {
// FIXME: Allow folding of values of any literal type in all languages.
if (Info.checkingPotentialConstantExpression() &&

2
clang/test/SemaCXX/constant-expression-cxx11.cpp
View File

@ -1195,7 +1195,7 @@ struct S {
int j : f(0); // expected-error {{constant expression}} expected-note {{in call to 'f(0)'}}
int k : g(0); // expected-error {{constant expression}} expected-note {{temporary created here}} expected-note {{in call to 'g(0)'}}
int l : n3; // expected-error {{constant expression}} expected-note {{read of non-const variable}}
int m : t.n; // expected-warning{{width of bit-field 'm' (42 bits)}}
int m : t.n; // expected-warning{{width of bit-field 'm' (42 bits)}} expected-warning{{expression is not an integral constant expression}} expected-note{{read of non-constexpr variable 't' is not allowed}}
};
}

19
clang/test/SemaCXX/constant-expression-cxx1y.cpp
View File

@ -959,18 +959,21 @@ namespace PR27989 {
}
namespace const_char {
template <int M, int N>
template <int N>
constexpr int sum(const char (&Arr)[N]) {
static_assert(N >= M, "");
int S = 0;
for (unsigned I = 0; I != M; ++I)
S += Arr[I];
for (unsigned I = 0; I != N; ++I)
S += Arr[I]; // expected-note 2{{read of non-constexpr variable 'Cs' is not allowed}}
return S;
}
// As an extension, we support evaluating some things that are `const` as though
// they were `constexpr`.
const char Cs[] = {'a', 'b', 'c'};
const int N = 2;
static_assert(sum<N>(Cs) == 'a' + 'b', "");
// they were `constexpr` when folding, but it should not be allowed in normal
// constexpr evaluation.
const char Cs[] = {'a', 'b'};
void foo() __attribute__((enable_if(sum(Cs) == 'a' + 'b', "")));
void run() { foo(); }
static_assert(sum(Cs) == 'a' + 'b', ""); // expected-error{{not an integral constant expression}} expected-note{{in call to 'sum(Cs)'}}
constexpr int S = sum(Cs); // expected-error{{must be initialized by a constant expression}} expected-note{{in call}}
}