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GH-54641: [C++] Support locale directives in the vendored strptime on Windows #54656

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Merged
kou merged 3 commits into from
Oct 20, 2026
Merged

GH-54641: [C++] Support locale directives in the vendored strptime on Windows #54656

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172c90f
GH-54641: [C++] Support locale directives in the vendored strptime on…
pearu Oct 19, 2026
1b6dfb1
Remove the fallback test switch and cite the source of the C-locale v…
pearu Oct 20, 2026
d367960
Run the R strptime tests for locale directives on Windows
pearu Oct 20, 2026
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32 changes: 32 additions & 0 deletions cpp/src/arrow/util/value_parsing_test.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -876,6 +876,38 @@ TEST(TimestampParser, StrptimeParser) {
}
}

TEST(TimestampParser, StrptimeLocaleDirectives) {
// Directives that use the names and formats of the C locale
struct Case {
std::string format;
std::string value;
std::string iso8601;
};

std::vector<Case> cases = {
{"%a %d %b %Y", "Sun 15 Feb 2015", "2015-02-15 00:00:00"},
{"%A %d %B %Y", "Sunday 15 February 2015", "2015-02-15 00:00:00"},
{"%d %h %Y", "15 Feb 2015", "2015-02-15 00:00:00"},
{"%d-%b-%Y", "15-feb-2015", "2015-02-15 00:00:00"},
{"%c", "Sun Feb 15 14:30:00 2015", "2015-02-15 14:30:00"},
{"%m/%d/%Y %I:%M %p", "02/15/2015 02:30 PM", "2015-02-15 14:30:00"},
{"%Y-%m-%d %r", "2015-02-15 02:30:00 PM", "2015-02-15 14:30:00"},
{"%x", "02/15/15", "2015-02-15 00:00:00"},
{"%Y-%m-%d %X", "2015-02-15 14:30:00", "2015-02-15 14:30:00"},
};

for (const auto& case_ : cases) {
SCOPED_TRACE(case_.format);
auto parser = TimestampParser::MakeStrptime(case_.format);
int64_t converted, expected;
ASSERT_TRUE(
(*parser)(case_.value.c_str(), case_.value.size(), TimeUnit::SECOND, &converted));
ASSERT_TRUE(ParseTimestampISO8601(case_.iso8601.c_str(), case_.iso8601.size(),
TimeUnit::SECOND, &expected));
ASSERT_EQ(expected, converted);
}
}

TEST(TimestampParser, StrptimeZoneOffset) {
if (!kStrptimeSupportsZone) {
GTEST_SKIP() << "strptime does not support %z on this platform";
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19 changes: 19 additions & 0 deletions cpp/src/arrow/vendored/musl/strptime.c
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Expand Up @@ -23,6 +23,25 @@

#ifdef HAVE_LANGINFO
#include <langinfo.h>
#else
// C-locale replacement for nl_langinfo(), restricted to the items used below.
// The values are those of the POSIX locale (LC_TIME in POSIX.1, chapter 7),
// as in musl's own C locale (c_time in src/locale/langinfo.c), and in the
// same order, which the symbolic_range loop relies on: full names directly
// follow the abbreviated ones.
enum { ABDAY_1 = 0, DAY_1 = 7, ABMON_1 = 14, MON_1 = 26, AM_STR = 38, PM_STR = 39,
D_T_FMT = 40, D_FMT = 41, T_FMT = 42, T_FMT_AMPM = 43 };
static const char *arrow_c_langinfo[] = {
"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat",
"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday",
"Jan", "Feb", "Mar", "Apr", "May", "Jun",
"Jul", "Aug", "Sep", "Oct", "Nov", "Dec",
"January", "February", "March", "April", "May", "June",
"July", "August", "September", "October", "November", "December",
"AM", "PM",
"%a %b %e %T %Y", "%m/%d/%y", "%H:%M:%S", "%I:%M:%S %p"};
Comment on lines +32 to +42

@kou kou Oct 20, 2026

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Could you mention where the values come from?

@pearu pearu Oct 20, 2026

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They are the values of the POSIX locale (LC_TIME in POSIX.1, chapter 7), which musl's own C locale (c_time in src/locale/langinfo.c) uses in the same order; glibc's C locale has the same values. Added this to the comment.

#define nl_langinfo(x) arrow_c_langinfo[x]
#define HAVE_LANGINFO 1
#endif

#define strptime arrow_strptime
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2 changes: 0 additions & 2 deletions r/tests/testthat/test-dplyr-funcs-datetime.R
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Expand Up @@ -238,8 +238,6 @@ test_that("strptime works for individual formats", {
collect()
)

# Some formats are not supported on Windows
skip_on_os("windows")
expect_equal(
strptime_test_df |>
arrow_table() |>
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