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Downgrade C++11 narrowing conversion errors to warnings default-mapped 

to an error, so that users can turn them off if necessary. Note that
this does *not* change the behavior of in a SFINAE context, where we
still flag an error even if the warning is disabled. This matches
GCC's behavior.

llvm-svn: 148701
This commit is contained in:
Douglas Gregor 2012-01-23 15:29:33 +00:00
parent c7f9fd4da8
commit 84585ab48e
4 changed files with 250 additions and 12 deletions
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15
clang/include/clang/Basic/DiagnosticSemaKinds.td
View File

@ -2942,13 +2942,22 @@ def warn_cxx98_compat_empty_scalar_initializer : Warning<
def err_illegal_initializer : Error<
"illegal initializer (only variables can be initialized)">;
def err_illegal_initializer_type : Error<"illegal initializer type %0">;
def err_init_list_type_narrowing : Error<
def err_init_list_type_narrowing_sfinae : Error<
"type %0 cannot be narrowed to %1 in initializer list">;
def err_init_list_variable_narrowing : Error<
def err_init_list_type_narrowing : Warning<
"type %0 cannot be narrowed to %1 in initializer list">,
InGroup<CXX11Narrowing>, DefaultError;
def err_init_list_variable_narrowing_sfinae : Error<
"non-constant-expression cannot be narrowed from type %0 to %1 in "
"initializer list">;
def err_init_list_constant_narrowing : Error<
def err_init_list_variable_narrowing : Warning<
"non-constant-expression cannot be narrowed from type %0 to %1 in "
"initializer list">, InGroup<CXX11Narrowing>, DefaultError;
def err_init_list_constant_narrowing_sfinae : Error<
"constant expression evaluates to %0 which cannot be narrowed to type %1">;
def err_init_list_constant_narrowing : Warning<
"constant expression evaluates to %0 which cannot be narrowed to type %1">,
InGroup<CXX11Narrowing>, DefaultError;
def warn_init_list_type_narrowing : Warning<
"type %0 cannot be narrowed to %1 in initializer list in C++11">,
InGroup<CXX11Narrowing>, DefaultIgnore;

24
clang/lib/Sema/SemaInit.cpp
View File

@ -5817,9 +5817,11 @@ static void DiagnoseNarrowingInInitList(Sema &S, InitializationSequence &Seq,
// narrowing conversion even if the value is a constant and can be
// represented exactly as an integer.
S.Diag(PostInit->getLocStart(),
S.getLangOptions().CPlusPlus0x && !S.getLangOptions().MicrosoftExt
? diag::err_init_list_type_narrowing
: diag::warn_init_list_type_narrowing)
S.getLangOptions().MicrosoftExt || !S.getLangOptions().CPlusPlus0x?
diag::warn_init_list_type_narrowing
: S.isSFINAEContext()?
diag::err_init_list_type_narrowing_sfinae
: diag::err_init_list_type_narrowing)
<< PostInit->getSourceRange()
<< PreNarrowingType.getLocalUnqualifiedType()
<< EntityType.getLocalUnqualifiedType();
@ -5828,9 +5830,11 @@ static void DiagnoseNarrowingInInitList(Sema &S, InitializationSequence &Seq,
case NK_Constant_Narrowing:
// A constant value was narrowed.
S.Diag(PostInit->getLocStart(),
S.getLangOptions().CPlusPlus0x && !S.getLangOptions().MicrosoftExt
? diag::err_init_list_constant_narrowing
: diag::warn_init_list_constant_narrowing)
S.getLangOptions().MicrosoftExt || !S.getLangOptions().CPlusPlus0x?
diag::warn_init_list_constant_narrowing
: S.isSFINAEContext()?
diag::err_init_list_constant_narrowing_sfinae
: diag::err_init_list_constant_narrowing)
<< PostInit->getSourceRange()
<< ConstantValue.getAsString(S.getASTContext(), EntityType)
<< EntityType.getLocalUnqualifiedType();
@ -5839,9 +5843,11 @@ static void DiagnoseNarrowingInInitList(Sema &S, InitializationSequence &Seq,
case NK_Variable_Narrowing:
// A variable's value may have been narrowed.
S.Diag(PostInit->getLocStart(),
S.getLangOptions().CPlusPlus0x && !S.getLangOptions().MicrosoftExt
? diag::err_init_list_variable_narrowing
: diag::warn_init_list_variable_narrowing)
S.getLangOptions().MicrosoftExt || !S.getLangOptions().CPlusPlus0x?
diag::warn_init_list_variable_narrowing
: S.isSFINAEContext()?
diag::err_init_list_variable_narrowing_sfinae
: diag::err_init_list_variable_narrowing)
<< PostInit->getSourceRange()
<< PreNarrowingType.getLocalUnqualifiedType()
<< EntityType.getLocalUnqualifiedType();

14
clang/test/CXX/dcl.decl/dcl.init/dcl.init.list/p7-0x.cpp
View File

@ -193,3 +193,17 @@ void test_qualifiers(int i) {
// Template arguments make it harder to avoid printing qualifiers:
Agg<const unsigned char> c2 = {j}; // expected-error {{from type 'int' to 'const unsigned char' in}} expected-note {{override}}
}
// Test SFINAE checks.
template<unsigned> struct Value { };
template<typename T>
int &check_narrowed(Value<sizeof((T){1.1})>);
template<typename T>
float &check_narrowed(...);
void test_narrowed(Value<sizeof(int)> vi, Value<sizeof(double)> vd) {
int &ir = check_narrowed<double>(vd);
float &fr = check_narrowed<int>(vi);
}

209
clang/test/CXX/dcl.decl/dcl.init/dcl.init.list/p7-cxx11-nowarn.cpp Normal file
View File

@ -0,0 +1,209 @@
// RUN: %clang_cc1 -fsyntax-only -std=c++11 -Wno-error=c++11-narrowing -triple x86_64-apple-macosx10.6.7 -verify %s
// Verify that narrowing conversions in initializer lists cause errors in C++0x
// mode.
void std_example() {
int x = 999; // x is not a constant expression
const int y = 999;
const int z = 99;
char c1 = x; // OK, though it might narrow (in this case, it does narrow)
char c2{x}; // expected-warning {{ cannot be narrowed }} expected-note {{override}}
char c3{y}; // expected-warning {{ cannot be narrowed }} expected-note {{override}} expected-warning {{changes value}}
char c4{z}; // OK: no narrowing needed
unsigned char uc1 = {5}; // OK: no narrowing needed
unsigned char uc2 = {-1}; // expected-warning {{ cannot be narrowed }} expected-note {{override}}
unsigned int ui1 = {-1}; // expected-warning {{ cannot be narrowed }} expected-note {{override}}
signed int si1 =
{ (unsigned int)-1 }; // expected-warning {{ cannot be narrowed }} expected-note {{override}}
int ii = {2.0}; // expected-warning {{ cannot be narrowed }} expected-note {{override}}
float f1 { x }; // expected-warning {{ cannot be narrowed }} expected-note {{override}}
float f2 { 7 }; // OK: 7 can be exactly represented as a float
int f(int);
int a[] =
{ 2, f(2), f(2.0) }; // OK: the double-to-int conversion is not at the top level
}
// Test each rule individually.
template<typename T>
struct Agg {
T t;
};
template<typename T>
struct Convert {
constexpr Convert(T v) : v(v) {}
constexpr operator T() const { return v; }
T v;
};
template<typename T> Convert<T> ConvertVar();
// C++0x [dcl.init.list]p7: A narrowing conversion is an implicit conversion
//
// * from a floating-point type to an integer type, or
void float_to_int() {
Agg<char> a1 = {1.0F}; // expected-warning {{type 'float' cannot be narrowed to 'char'}} expected-note {{override}}
Agg<char> a2 = {1.0}; // expected-warning {{ cannot be narrowed }} expected-note {{override}}
Agg<char> a3 = {1.0L}; // expected-warning {{ cannot be narrowed }} expected-note {{override}}
float f = 1.0;
double d = 1.0;
long double ld = 1.0;
Agg<char> a4 = {f}; // expected-warning {{ cannot be narrowed }} expected-note {{override}}
Agg<char> a5 = {d}; // expected-warning {{ cannot be narrowed }} expected-note {{override}}
Agg<char> a6 = {ld}; // expected-warning {{ cannot be narrowed }} expected-note {{override}}
Agg<char> ce1 = { Convert<float>(1.0) }; // expected-warning {{type 'float' cannot be narrowed to 'char'}} expected-note {{override}}
Agg<char> ce2 = { ConvertVar<double>() }; // expected-warning {{type 'double' cannot be narrowed to 'char'}} expected-note {{override}}
}
// * from long double to double or float, or from double to float, except where
// the source is a constant expression and the actual value after conversion
// is within the range of values that can be represented (even if it cannot be
// represented exactly), or
void shrink_float() {
// These aren't constant expressions.
float f = 1.0;
double d = 1.0;
long double ld = 1.0;
// Variables.
Agg<float> f1 = {f}; // OK (no-op)
Agg<float> f2 = {d}; // expected-warning {{non-constant-expression cannot be narrowed from type 'double' to 'float'}} expected-note {{override}}
Agg<float> f3 = {ld}; // expected-warning {{ cannot be narrowed }} expected-note {{override}}
// Exact constants.
Agg<float> f4 = {1.0}; // OK (double constant represented exactly)
Agg<float> f5 = {1.0L}; // OK (long double constant represented exactly)
// Inexact but in-range constants.
Agg<float> f6 = {0.1}; // OK (double constant in range but rounded)
Agg<float> f7 = {0.1L}; // OK (long double constant in range but rounded)
// Out of range constants.
Agg<float> f8 = {1E50}; // expected-warning {{constant expression evaluates to 1.000000e+50 which cannot be narrowed to type 'float'}} expected-note {{override}}
Agg<float> f9 = {1E50L}; // expected-warning {{ cannot be narrowed }} expected-note {{override}}
// More complex constant expression.
constexpr long double e40 = 1E40L, e30 = 1E30L, e39 = 1E39L;
Agg<float> f10 = {e40 - 5 * e39 + e30 - 5 * e39}; // OK
// Variables.
Agg<double> d1 = {f}; // OK (widening)
Agg<double> d2 = {d}; // OK (no-op)
Agg<double> d3 = {ld}; // expected-warning {{ cannot be narrowed }} expected-note {{override}}
// Exact constant.
Agg<double> d4 = {1.0L}; // OK (long double constant represented exactly)
// Inexact but in-range constant.
Agg<double> d5 = {0.1L}; // OK (long double constant in range but rounded)
// Out of range constant.
Agg<double> d6 = {1E315L}; // expected-warning {{ cannot be narrowed }} expected-note {{override}}
// More complex constant expression.
constexpr long double e315 = 1E315L, e305 = 1E305L, e314 = 1E314L;
Agg<double> d7 = {e315 - 5 * e314 + e305 - 5 * e314}; // OK
Agg<float> ce1 = { Convert<double>(1e300) }; // expected-warning {{constant expression evaluates to 1.000000e+300 which cannot be narrowed to type 'float'}} expected-note {{override}}
Agg<double> ce2 = { ConvertVar<long double>() }; // expected-warning {{non-constant-expression cannot be narrowed from type 'long double' to 'double'}} expected-note {{override}}
}
// * from an integer type or unscoped enumeration type to a floating-point type,
// except where the source is a constant expression and the actual value after
// conversion will fit into the target type and will produce the original
// value when converted back to the original type, or
void int_to_float() {
// Not a constant expression.
char c = 1;
// Variables. Yes, even though all char's will fit into any floating type.
Agg<float> f1 = {c}; // expected-warning {{ cannot be narrowed }} expected-note {{override}}
Agg<double> f2 = {c}; // expected-warning {{ cannot be narrowed }} expected-note {{override}}
Agg<long double> f3 = {c}; // expected-warning {{ cannot be narrowed }} expected-note {{override}}
// Constants.
Agg<float> f4 = {12345678}; // OK (exactly fits in a float)
Agg<float> f5 = {123456789}; // expected-warning {{ cannot be narrowed }} expected-note {{override}}
Agg<float> ce1 = { Convert<int>(123456789) }; // expected-warning {{constant expression evaluates to 123456789 which cannot be narrowed to type 'float'}} expected-note {{override}}
Agg<double> ce2 = { ConvertVar<long long>() }; // expected-warning {{non-constant-expression cannot be narrowed from type 'long long' to 'double'}} expected-note {{override}}
}
// * from an integer type or unscoped enumeration type to an integer type that
// cannot represent all the values of the original type, except where the
// source is a constant expression and the actual value after conversion will
// fit into the target type and will produce the original value when converted
// back to the original type.
void shrink_int() {
// Not a constant expression.
short s = 1;
unsigned short us = 1;
Agg<char> c1 = {s}; // expected-warning {{ cannot be narrowed }} expected-note {{override}}
Agg<unsigned short> s1 = {s}; // expected-warning {{ cannot be narrowed }} expected-note {{override}}
Agg<short> s2 = {us}; // expected-warning {{ cannot be narrowed }} expected-note {{override}}
// "that cannot represent all the values of the original type" means that the
// validity of the program depends on the relative sizes of integral types.
// This test compiles with -m64, so sizeof(int)<sizeof(long)==sizeof(long
// long).
long l1 = 1;
Agg<int> i1 = {l1}; // expected-warning {{ cannot be narrowed }} expected-note {{override}}
long long ll = 1;
Agg<long> l2 = {ll}; // OK
// Constants.
Agg<char> c2 = {127}; // OK
Agg<char> c3 = {300}; // expected-warning {{ cannot be narrowed }} expected-note {{override}} expected-warning {{changes value}}
Agg<int> i2 = {0x7FFFFFFFU}; // OK
Agg<int> i3 = {0x80000000U}; // expected-warning {{ cannot be narrowed }} expected-note {{override}}
Agg<unsigned int> i4 = {-0x80000000L}; // expected-warning {{ cannot be narrowed }} expected-note {{override}}
// Bool is also an integer type, but conversions to it are a different AST
// node.
Agg<bool> b1 = {0}; // OK
Agg<bool> b2 = {1}; // OK
Agg<bool> b3 = {-1}; // expected-warning {{ cannot be narrowed }} expected-note {{override}}
// Conversions from pointers to booleans aren't narrowing conversions.
Agg<bool> b = {&b1}; // OK
Agg<short> ce1 = { Convert<int>(100000) }; // expected-warning {{constant expression evaluates to 100000 which cannot be narrowed to type 'short'}} expected-note {{override}} expected-warning {{changes value from 100000 to -31072}}
Agg<char> ce2 = { ConvertVar<short>() }; // expected-warning {{non-constant-expression cannot be narrowed from type 'short' to 'char'}} expected-note {{override}}
}
// Be sure that type- and value-dependent expressions in templates get the warning
// too.
template<int I, typename T>
void maybe_shrink_int(T t) {
Agg<short> s1 = {t}; // expected-warning {{ cannot be narrowed }} expected-note {{override}}
Agg<short> s2 = {I}; // expected-warning {{ cannot be narrowed }} expected-note {{override}} expected-warning {{changes value}}
Agg<T> t2 = {700}; // expected-warning {{ cannot be narrowed }} expected-note {{override}} expected-warning {{changes value}}
}
void test_template() {
maybe_shrink_int<15>((int)3); // expected-note {{in instantiation}}
maybe_shrink_int<70000>((char)3); // expected-note {{in instantiation}}
}
// We don't want qualifiers on the types in the diagnostic.
void test_qualifiers(int i) {
const int j = i;
struct {const unsigned char c;} c1 = {j}; // expected-warning {{from type 'int' to 'unsigned char' in}} expected-note {{override}}
// Template arguments make it harder to avoid printing qualifiers:
Agg<const unsigned char> c2 = {j}; // expected-warning {{from type 'int' to 'const unsigned char' in}} expected-note {{override}}
}
// Make sure we still get the right SFINAE behavior.
template<unsigned> struct Value { };
template<typename T>
int &check_narrowed(Value<sizeof((T){1.1})>);
template<typename T>
float &check_narrowed(...);
void test_narrowed(Value<sizeof(int)> vi, Value<sizeof(double)> vd) {
int &ir = check_narrowed<double>(vd);
float &fr = check_narrowed<int>(vi);
}