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Disallow passing non-string-literals to FMT_STRING

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This commit is contained in:
Victor Zverovich 2020-01-22 19:08:06 -08:00
parent 419db8baa1
commit 09a13244c8
2 changed files with 6 additions and 11 deletions
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14
include/fmt/format.h
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@ -3449,13 +3449,10 @@ template <typename Char> struct udl_arg {
}
};
// A constexpr version of strlen.
template <typename Char> FMT_CONSTEXPR size_t compute_length(const Char* s) {
size_t len = 0;
while (*s++) ++len;
return len;
template <typename Char, size_t N>
FMT_CONSTEXPR basic_string_view<Char> literal_to_view(const Char (&s)[N]) {
return {s, N - 1};
}
} // namespace internal
inline namespace literals {
@ -3519,7 +3516,8 @@ FMT_END_NAMESPACE
using char_type = fmt::remove_cvref_t<decltype(*s)>; \
__VA_ARGS__ FMT_CONSTEXPR \
operator fmt::basic_string_view<char_type>() const { \
return {s, fmt::internal::compute_length(s)}; \
/* FMT_STRING only accepts string literals. */ \
return fmt::internal::literal_to_view(s); \
} \
}; \
return FMT_STRING(); \
@ -3527,7 +3525,7 @@ FMT_END_NAMESPACE
/**
\rst
Constructs a compile-time format string.
Constructs a compile-time format string from a string literal *s*.
**Example**::

3
test/format-test.cc
View File

@ -1849,10 +1849,7 @@ TEST(FormatTest, UnpackedArgs) {
struct string_like {};
fmt::string_view to_string_view(string_like) { return "foo"; }
FMT_CONSTEXPR_DECL const char* format_str_ptr = "0123456789";
TEST(FormatTest, CompileTimeString) {
EXPECT_EQ(format_str_ptr, fmt::format(FMT_STRING(format_str_ptr)));
EXPECT_EQ("42", fmt::format(FMT_STRING("{}"), 42));
EXPECT_EQ(L"42", fmt::format(FMT_STRING(L"{}"), 42));
EXPECT_EQ("foo", fmt::format(FMT_STRING("{}"), string_like()));