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Report error on duplicate named arg names #4367

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Merged
vitaut merged 10 commits into from
Mar 2, 2025
Merged

Report error on duplicate named arg names #4367

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167ec54
Report error on duplicate named arg names
dinomight Feb 22, 2025
233d8d9
Fix unused return warning
dinomight Feb 26, 2025
3d9a3e6
Fix formatting
dinomight Feb 26, 2025
93b1425
Refactor check function, optimize check function, remove expensive test
dinomight Mar 1, 2025
36a6908
Fix missing CTAD in C++11
dinomight Mar 1, 2025
b6be6fe
Fix GCC13 build and enable GCC10 C++11 build
dinomight Mar 1, 2025
1c156a3
Fix formatting
dinomight Mar 1, 2025
9800147
Fix formatting, again
dinomight Mar 1, 2025
7cf7957
Remove init methods, simplify const usage, simplify check function, r…
dinomight Mar 2, 2025
e3bfecd
Run clang-format
dinomight Mar 2, 2025
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18 changes: 18 additions & 0 deletions include/fmt/base.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1060,17 +1060,34 @@ template <typename... Args> constexpr auto count_static_named_args() -> int {
}

template <typename Char> struct named_arg_info {
FMT_CONSTEXPR named_arg_info() : name(nullptr), id(0) {}
FMT_CONSTEXPR named_arg_info(const Char* a_name, const int an_id)
: name(a_name), id(an_id) {}
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@vitaut vitaut Mar 1, 2025

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Initialization is done in init*named_arg, we shouldn't duplicate it here.

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@dinomight dinomight Mar 2, 2025

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I'm going to try your idea of only calling if the index is greater than zero, but if that doesn't work, I need the default construct and if I have the default construct, GCC10 will need the other one.

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@dinomight dinomight Mar 2, 2025

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Both functions have been removed. The if check appeased GCC13, it seems.

const Char* name;
int id;
};

template <typename Char>
FMT_CONSTEXPR void check_for_duplicate(
const named_arg_info<Char>* const named_args, const int named_arg_index,
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@vitaut vitaut Mar 1, 2025

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Let's not overuse const - it just clutters the code without bringing much benefit when the scope is small.

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@dinomight dinomight Mar 2, 2025 •
edited
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I just want my immutable by default like rust 😄 . This is also an area I disagree with the CPP core guidelines. I'll begrudgingly update this, though.

const Char* const arg_name) {
const basic_string_view<Char> arg_name_view(arg_name);
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@vitaut vitaut Mar 1, 2025

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You can simplify this by passing arg_name as a string_view.

for (auto i = 0; i < named_arg_index; ++i) {
if (basic_string_view<Char>(named_args[i].name) == arg_name_view) {
report_error("duplicate named args found");
}
}
}

template <typename Char, typename T, FMT_ENABLE_IF(!is_named_arg<T>::value)>
void init_named_arg(named_arg_info<Char>*, int& arg_index, int&, const T&) {
++arg_index;
}

template <typename Char, typename T, FMT_ENABLE_IF(is_named_arg<T>::value)>
void init_named_arg(named_arg_info<Char>* named_args, int& arg_index,
int& named_arg_index, const T& arg) {
check_for_duplicate(named_args, named_arg_index, arg.name);
named_args[named_arg_index++] = {arg.name, arg_index++};
}

Expand All @@ -1084,6 +1101,7 @@ template <typename T, typename Char,
FMT_ENABLE_IF(is_static_named_arg<T>::value)>
FMT_CONSTEXPR void init_static_named_arg(named_arg_info<Char>* named_args,
int& arg_index, int& named_arg_index) {
check_for_duplicate(named_args, named_arg_index, T::name);
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@vitaut vitaut Mar 1, 2025

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I wonder if calling check_for_duplicate only if named_arg_index is nonzero fixes the uninitialized warning.

named_args[named_arg_index++] = {T::name, arg_index++};
}

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2 changes: 2 additions & 0 deletions test/format-test.cc
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Expand Up @@ -599,6 +599,8 @@ TEST(format_test, named_arg) {
EXPECT_THROW_MSG((void)fmt::format(runtime("{a} {}"), fmt::arg("a", 2), 42),
format_error,
"cannot switch from manual to automatic argument indexing");
EXPECT_THROW_MSG((void)fmt::format("{a}", fmt::arg("a", 1),
fmt::arg("a", 10)), format_error, "duplicate named args found");
}

TEST(format_test, auto_arg_index) {
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