strtod() 不尊重 macOS 13.3.1 上的区域设置

Question

在 macOS 13.3.1 上，strtod()似乎不尊重使用设置的区域设置uselocale()，并且无法正确处理小数点/逗号。这是 macOS 中的错误吗？有解决方法吗？

这是一个测试程序，它演示了这一点printf()并scanf()尊重小数点设置，但strtod()事实并非如此。

#include <locale.h>
#include <xlocale.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>

int main() {
    double x;
    const char *num = "12.3";
    char *end;

    // First we set the locale globally to something that uses decimal
    // commas instead of decimal points.
    const char *locname = setlocale(LC_ALL, "de_DE");
    struct lconv *lc = localeconv();
    if (strcmp(lc->decimal_point, ",")) {
        /* If decimal point is not a comma, presumably because the requested
         * locale was not available, report locale information and quit. */
        fprintf(stderr, "setlocale() returned '%s', decimal point is '%s'\n",
                locname ? locname : "NULL",
                lc->decimal_point);
        abort();
    }

    // In this locale, printf() uses decimal commas, and both scanf() and strtod()
    // assume decimal commas when reading numbers. Thus when reading 12.3, both
    // of these function stop reading as soon as they reach the '.' character.
    printf("Using locale with decimal comma:\n");
    x = 0.0;
    printf("%g\n", 12.3);
    sscanf(num, "%lf", &x);
    printf("%g\n", x);
    x = strtod(num, &end);
    printf("%g\n", x);

    // Now we set the numeric local to use decimal points in a thread-local manner
    // using the non-standard uselocale().
    locale_t c_locale = newlocale(LC_NUMERIC_MASK, "C", NULL);
    assert(c_locale != NULL);
    uselocale(c_locale);

    // Now both scanf() and strtod() should be assuming a decimal point,
    // and both should read 12.3 in full.
    printf("\nUsing locale with decimal point:\n");
    x = 0.0;
    printf("%g\n", 12.3);
    sscanf("12.3", "%lf", &x);
    printf("%g\n", x);
    x = strtod(num, &end);
    printf("%g\n", x);

    return 0;
}

macOS 10.14.6 上的输出符合我的预期：

Using locale with decimal comma:
12,3
12
12

Using locale with decimal point:
12.3
12.3
12.3

macOS 13.3.1 上的输出：

Using locale with decimal comma:
12,3
12
12

Using locale with decimal point:
12.3
12.3
12

请注意，strtod()读数没有超过小数点。

---

注意：这是因为它导致 igraph 测试套件失败而被发现的。问题报告在这里。

Answer 1

看来 MacOS Ventura 标准库确实存在错误，请参阅我们的错误报告 https://github.com/prusa3d/PrusaSlicer/issues/10331