fix zero flag for char types and make zero flag ignored if a precisio…

…n is specified
fmtlib · May 23, 2020 · 8c8f74a · 8c8f74a
1 parent bc1b89d
commit 8c8f74a
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Showing 2 changed files with 9 additions and 1 deletion.
diff --git a/include/fmt/printf.h b/include/fmt/printf.h
@@ -257,6 +257,7 @@ class printf_arg_formatter : public detail::arg_formatter_base<Range> {
         return (*this)(static_cast<int>(value));
       fmt_specs.sign = sign::none;
       fmt_specs.alt = false;
+      fmt_specs.fill[0] = ' ';  // Ignore '0' flag for char types.
       // align::numeric needs to be overwritten here since the '0' flag is
       // ignored for non-numeric types
       if (fmt_specs.align == align::none || fmt_specs.align == align::numeric)
@@ -508,6 +509,10 @@ OutputIt basic_printf_context<OutputIt, Char>::format() {
     }
 
     format_arg arg = get_arg(arg_index);
+    // For d, i, o, u, x, and X conversion specifiers, if a precision is
+    // specified, the '0' flag is ignored
+    if (specs.precision >= 0 && arg.is_integral())
+      specs.fill[0] = ' ';  // Ignore '0' flag for non-numeric types or if '-' present.
     if (specs.precision >= 0 && arg.type() == detail::type::cstring_type) {
       auto str = visit_format_arg(detail::get_cstring<Char>(), arg);
       auto str_end = str + specs.precision;

diff --git a/test/printf-test.cc b/test/printf-test.cc
@@ -139,8 +139,11 @@ TEST(PrintfTest, ZeroFlag) {
 
   EXPECT_PRINTF("+00042", "%00+6d", 42);
 
+  EXPECT_PRINTF("   42", "%05.d", 42);
+  EXPECT_PRINTF(" 0042", "%05.4d", 42);
+
   // '0' flag is ignored for non-numeric types.
-  EXPECT_PRINTF("0000x", "%05c", 'x');
+  EXPECT_PRINTF("    x", "%05c", 'x');
 }
 
 TEST(PrintfTest, PlusFlag) {