test: Add some floating point conversion corner cases

glibc uses the special value 3752432815e-39 to test strtod, strtof and
sscanf. In hex, it's just a bit more than 0x1.306efbp-98 while
3752432815e-39 is just a bit less.  Doing a conversion to float should
yield 0x1.306efcp-98, but slighty incautious code might generate
0x1.306efap-98 instead.

Signed-off-by: Keith Packard <[email protected]>

Author: keith-packard

test/libc-testsuite/sscanf.c

@@ -35,7 +35,7 @@
 
 #define TEST_F(x) ( \
 TEST(i, sscanf(# x, "%lf", &d), 1, "got %d fields, expected %d"), \
-TEST(t, d, (double)x, "%g != %g") )
+TEST(t, d, (double)x, "%a != %a") )
 
 #pragma GCC diagnostic ignored "-Wpragmas"
 #pragma GCC diagnostic ignored "-Wunknown-warning-option"
@@ -137,6 +137,7 @@ static int test_sscanf(void)
 	TEST_F(0.2);
 	TEST_F(0.1e-10);
 	TEST_F(0x1234p56);
+        TEST_F(3752432815e-39);
 
 #ifndef __PICOLIBC__
         /* both tinystdio and legacy stdio fail this test */

test/printf_scanf.c

@@ -514,8 +514,11 @@ main(void)
 			sscanf(buf, scanf_format, &r);
 			e = fabs(v-r) / v;
 			if (e > (float_type) ERROR_MAX) {
-				printf("\tf %3d: wanted %.7e got %.7e (error %.7e, buf %s)\n", x,
-				       printf_float(v), printf_float(r), printf_float(e), buf);
+				printf("\tf %3d: wanted %.7e %a got %.7e %a (error %.7e %a, buf %s)\n", x,
+				       printf_float(v), printf_float(v),
+                                       printf_float(r), printf_float(r),
+                                       printf_float(e), printf_float(e),
+                                       buf);
 				errors++;
 				fflush(stdout);
 			}

test/test-strtod.c

@@ -57,6 +57,12 @@ static const struct {
 } tests[] = {
     { "1e2@", 100.0, 100.0f, 100.0l, "@" },
 #ifdef FULL_TESTS
+#if !defined(TINY_STDIO) || defined(_IO_FLOAT_EXACT)
+    { "3752432815e-39%", 0x1.306efbp-98, 0x1.306efcp-98f, 3752432815e-39l, "%" },
+    { "3.752432815e-30%", 0x1.306efbp-98, 0x1.306efcp-98f, 3752432815e-39l, "%" },
+    { "3752432814e-39^", 3752432814e-39, 0x1.306efap-98f, 3752432814e-39l, "^" },
+    { "3.752432814e-30^", 3752432814e-39, 0x1.306efap-98f, 3752432814e-39l, "^" },
+#endif
     { "0x10.000@", 16.0, 16.0f, 16.0l, "@" },
     { "0x10.000p@", 16.0, 16.0f, 16.0l, "p@" },
     { "0x10.000p+@", 16.0, 16.0f, 16.0l, "p+@" },
@@ -158,9 +164,18 @@ int main(void)
                    tests[i].string, end, tests[i].end_test);
             ret = 1;
         }
+        if (tests[i].end_test[0] == '%') {
+            if ((float) d != f) {
+                printf("strtof(\"%s\") got %a strtod got %a\n", tests[i].string, (double) f, d);
+                ret = 1;
+            }
+        }
 #ifdef _TEST_LONG_DOUBLE
 #ifdef FULL_TESTS
-        if (sizeof(long double) > sizeof(double)) {
+        if (sizeof(long double) > sizeof(double)
+            && tests[i].end_test[0] != '%'
+            && tests[i].end_test[0] != '^')
+        {
             ld = strtold(tests[i].string, &end);
             if (ld != tests[i].ldvalue) {
                 printf("strtold(\"%s\"): got %.17Le %La want %.17Le %La\n", tests[i].string,

test/testcases.c

@@ -702,6 +702,7 @@
     result |= test(__LINE__, "0x0p-126", "%.a", 0x1p-127);
 #endif
 #else
+    result |= test(__LINE__, "0x1.306efbp-98", "%a", 3752432815e-39);
 #ifdef NORMALIZED_A
     /* newlib legacy stdio normalizes %a format */
     result |= test(__LINE__, "0x1p-1074", "%a", 0x1p-1074);