Add unit tests and doc for the %Lf large precision issue on Solaris.

* tests/test-vasnprintf-posix.c (test_function): Add a testcase for
"%.5119Lf".
* tests/test-vasprintf-posix.c (test_function): Likewise.
* tests/test-snprintf-posix.h (test_function): Likewise.
* tests/test-sprintf-posix.h (test_function): Likewise.
* tests/test-vasnwprintf-posix.c (test_function): Likewise.
* doc/posix-functions/*printf.texi: Document the Solaris 11.4 bug.

ChangeLog

@@ -1,3 +1,14 @@
+2026-08-14  Bruno Haible  <bruno@clisp.org>
+
+	Add unit tests and doc for the %Lf large precision issue on Solaris.
+	* tests/test-vasnprintf-posix.c (test_function): Add a testcase for
+	"%.5119Lf".
+	* tests/test-vasprintf-posix.c (test_function): Likewise.
+	* tests/test-snprintf-posix.h (test_function): Likewise.
+	* tests/test-sprintf-posix.h (test_function): Likewise.
+	* tests/test-vasnwprintf-posix.c (test_function): Likewise.
+	* doc/posix-functions/*printf.texi: Document the Solaris 11.4 bug.
+
 2026-08-14  Pádraig Brady  <P@draigBrady.com>
 
 	tests: avoid -Wformat= warning re unsigned mismatch

doc/posix-functions/fprintf.texi

@@ -103,7 +103,7 @@ AIX 7.1, Solaris 10/x86, mingw, MSVC/clang.
 This function mishandles large floating point precisions
 (for example, formatting 1.0 with @samp{"%.511f"})
 on some platforms:
-Solaris 10.
+Solaris 11.4.
 @item
 This function produces wrong output for the @samp{lc} directive with a NUL
 wide character argument on some platforms:

doc/posix-functions/printf.texi

@@ -103,7 +103,7 @@ AIX 7.1, Solaris 10/x86, mingw, MSVC/clang.
 This function mishandles large floating point precisions
 (for example, formatting 1.0 with @samp{"%.511f"})
 on some platforms:
-Solaris 10.
+Solaris 11.4.
 @item
 This function produces wrong output for the @samp{lc} directive with a NUL
 wide character argument on some platforms:

doc/posix-functions/snprintf.texi

@@ -102,7 +102,7 @@ AIX 7.1, Solaris 10/x86, mingw, MSVC/clang.
 This function mishandles large floating point precisions
 (for example, formatting 1.0 with @samp{"%.511f"})
 on some platforms:
-Solaris 10.
+Solaris 11.4.
 @item
 This function produces wrong output for the @samp{lc} directive with a NUL
 wide character argument on some platforms:

doc/posix-functions/sprintf.texi

@@ -90,7 +90,7 @@ AIX 7.1, Solaris 10/x86, mingw, MSVC/clang.
 This function mishandles large floating point precisions
 (for example, formatting 1.0 with @samp{"%.511f"})
 on some platforms:
-Solaris 10.
+Solaris 11.4.
 @item
 This function produces wrong output for the @samp{lc} directive with a NUL
 wide character argument on some platforms:

doc/posix-functions/vfprintf.texi

@@ -103,7 +103,7 @@ AIX 7.1, Solaris 10/x86, mingw, MSVC/clang.
 This function mishandles large floating point precisions
 (for example, formatting 1.0 with @samp{"%.511f"})
 on some platforms:
-Solaris 10.
+Solaris 11.4.
 @item
 This function produces wrong output for the @samp{lc} directive with a NUL
 wide character argument on some platforms:

doc/posix-functions/vprintf.texi

@@ -103,7 +103,7 @@ AIX 7.1, Solaris 10/x86, mingw, MSVC/clang.
 This function mishandles large floating point precisions
 (for example, formatting 1.0 with @samp{"%.511f"})
 on some platforms:
-Solaris 10.
+Solaris 11.4.
 @item
 This function produces wrong output for the @samp{lc} directive with a NUL
 wide character argument on some platforms:

doc/posix-functions/vsnprintf.texi

@@ -99,7 +99,7 @@ AIX 7.1, Solaris 10/x86, mingw, MSVC/clang.
 This function mishandles large floating point precisions
 (for example, formatting 1.0 with @samp{"%.511f"})
 on some platforms:
-Solaris 10.
+Solaris 11.4.
 @item
 This function produces wrong output for the @samp{lc} directive with a NUL
 wide character argument on some platforms:

doc/posix-functions/vsprintf.texi

@@ -90,7 +90,7 @@ AIX 7.1, Solaris 10/x86, mingw, MSVC/clang.
 This function mishandles large floating point precisions
 (for example, formatting 1.0 with @samp{"%.511f"})
 on some platforms:
-Solaris 10.
+Solaris 11.4.
 @item
 This function produces wrong output for the @samp{lc} directive with a NUL
 wide character argument on some platforms:

tests/test-snprintf-posix.h

@@ -79,7 +79,7 @@ static void
 test_function (int (*my_snprintf) (char *, size_t, const char *, ...))
 {
   char buf[8];
-  char result[5000];
+  char result[10000];
 
   /* Test return value convention.  */
 
@@ -2955,6 +2955,17 @@ test_function (int (*my_snprintf) (char *, size_t, const char *, ...))
     ASSERT (retval == strlen (result));
   }
 
+  {
+    int retval =
+      my_snprintf (result, sizeof (result), "%.5119Lf %d", 1.0L, 99);
+    ASSERT (result[0] == '1');
+    ASSERT (result[1] == '.');
+    for (size_t i = 0; i < 5119; i++)
+      ASSERT (result[2 + i] == '0');
+    ASSERT (streq (result + 2 + 5119, " 99"));
+    ASSERT (retval == strlen (result));
+  }
+
   {
     char input[5000];
     int retval;

tests/test-sprintf-posix.h

@@ -78,7 +78,7 @@ strisnan (const char *string, size_t start_index, size_t end_index, int uppercas
 static void
 test_function (int (*my_sprintf) (char *, const char *, ...))
 {
-  char result[5000];
+  char result[10000];
   char buf[8];
 
   /* Test return value convention.  */
@@ -2942,6 +2942,17 @@ test_function (int (*my_sprintf) (char *, const char *, ...))
     ASSERT (retval == strlen (result));
   }
 
+  {
+    int retval =
+      my_sprintf (result, "%.5119Lf %d", 1.0L, 99);
+    ASSERT (result[0] == '1');
+    ASSERT (result[1] == '.');
+    for (size_t i = 0; i < 5119; i++)
+      ASSERT (result[2 + i] == '0');
+    ASSERT (streq (result + 2 + 5119, " 99"));
+    ASSERT (retval == strlen (result));
+  }
+
   {
     char input[5000];
     int retval;

tests/test-vasnprintf-posix.c

@@ -3809,6 +3809,20 @@ test_function (char * (*my_asnprintf) (char *, size_t *, const char *, ...))
     free (result);
   }
 
+  {
+    size_t length;
+    char *result =
+      my_asnprintf (NULL, &length, "%.5119Lf %d", 1.0L, 99);
+    ASSERT (result != NULL);
+    ASSERT (result[0] == '1');
+    ASSERT (result[1] == '.');
+    for (size_t i = 0; i < 5119; i++)
+      ASSERT (result[2 + i] == '0');
+    ASSERT (streq (result + 2 + 5119, " 99"));
+    ASSERT (length == strlen (result));
+    free (result);
+  }
+
   {
     char input[5000];
     size_t length;

tests/test-vasnwprintf-posix.c

@@ -3813,6 +3813,20 @@ test_function (wchar_t * (*my_asnwprintf) (wchar_t *, size_t *, const wchar_t *,
     free (result);
   }
 
+  {
+    size_t length;
+    wchar_t *result =
+      my_asnwprintf (NULL, &length, L"%.5119Lf %d", 1.0L, 99);
+    ASSERT (result != NULL);
+    ASSERT (result[0] == '1');
+    ASSERT (result[1] == '.');
+    for (size_t i = 0; i < 5119; i++)
+      ASSERT (result[2 + i] == '0');
+    ASSERT (wcscmp (result + 2 + 5119, L" 99") == 0);
+    ASSERT (length == wcslen (result));
+    free (result);
+  }
+
   {
     char input[5000];
     size_t length;

tests/test-vasprintf-posix.c

@@ -3793,6 +3793,20 @@ test_function (int (*my_asprintf) (char **, const char *, ...))
     free (result);
   }
 
+  {
+    char *result;
+    int retval =
+      my_asprintf (&result, "%.5119Lf %d", 1.0L, 99);
+    ASSERT (result != NULL);
+    ASSERT (result[0] == '1');
+    ASSERT (result[1] == '.');
+    for (size_t i = 0; i < 5119; i++)
+      ASSERT (result[2 + i] == '0');
+    ASSERT (streq (result + 2 + 5119, " 99"));
+    ASSERT (retval == strlen (result));
+    free (result);
+  }
+
   {
     char input[5000];
     char *result;