[v2] libstdc++: Fix error handling in std::print
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Commit Message
On Tue, 27 Feb 2024 at 15:21, Tim Song wrote:
>
> [print.fun] requires a system_error, but I don't think [ostream.formatted.print] does?
Yeah it looks like I got confused (again) jumping back and forth
between [print.fun] and [ostream.formatted.print]. So we're doing the
right thing, and should just add tests to verify that.
commit e1c689dbeb5b6364eb2a2f0af20ced07b8096b82
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Thu Feb 22 13:06:59 2024
libstdc++: Test error handling in std::print
The standard requires an exception if std::print fails to write to a
FILE*. When writing to a std::ostream, failure to format the arguments
doesn't affect the stream state, but failure to write to the streadm
sets badbit.
libstdc++-v3/ChangeLog:
* testsuite/27_io/basic_ostream/print/1.cc: Check error
handling.
* testsuite/27_io/print/1.cc: Likewise.
@@ -103,6 +103,40 @@ test_locale()
}
}
+void
+test_errors()
+{
+ // Failure to generate output is reported by setting badbit.
+ std::stringstream in(std::ios::in);
+ std::print(in, "{}", "nope"); // No exception here.
+ VERIFY(in.bad());
+#ifdef __cpp_exceptions
+ in.clear();
+ in.exceptions(std::ios::badbit);
+ try
+ {
+ std::print(in, "{}", "nope"); // Should throw now.
+ VERIFY(false);
+ }
+ catch (const std::ios::failure&)
+ {
+ }
+
+ // An exception thrown when formatting the string is propagated
+ // without setting badbit.
+ std::ostringstream out;
+ try
+ {
+ std::vprint_nonunicode(out, "{}", std::make_format_args());
+ VERIFY(false);
+ }
+ catch (const std::format_error&)
+ {
+ }
+ VERIFY(out.good());
+#endif
+}
+
int main()
{
test_print_ostream();
@@ -111,4 +145,5 @@ int main()
test_print_no_padding();
test_vprint_nonunicode();
test_locale();
+ test_errors();
}
@@ -74,6 +74,21 @@ test_vprint_nonunicode()
// { dg-output "garbage in . garbage out" }
}
+void
+test_errors()
+{
+#ifdef __cpp_exceptions
+ try
+ {
+ std::print(stdin, "{}", "nope");
+ VERIFY(false);
+ }
+ catch (const std::system_error&)
+ {
+ }
+#endif
+}
+
int main()
{
test_print_default();
@@ -82,4 +97,5 @@ int main()
test_println_file();
test_print_raw();
test_vprint_nonunicode();
+ test_errors();
}