Make arg_expand_all not short-circuit on first error

tests/rustdoc-ui/argfile/commandline-argfile-missing-windows.rs

@@ -0,0 +1,19 @@
+// Check to see if we can get parameters from an @argsfile file
+//
+// Path replacement in .stderr files (i.e. `$DIR`) doesn't handle mixed path
+// separators. This test uses backslash as the path separator for the command
+// line arguments and is only run on windows.
+//
+//@ only-windows
+//@ normalize-stderr-test: "os error \d+" -> "os error $$ERR"
+//@ normalize-stderr-test: "commandline-argfile-missing.args:[^(]*" -> "commandline-argfile-missing.args: $$FILE_MISSING "
+//@ compile-flags: --cfg cmdline_set @{{src-base}}\argfile\commandline-argfile-missing.args
+
+#[cfg(not(cmdline_set))]
+compile_error!("cmdline_set not set");
+
+#[cfg(not(unbroken))]
+compile_error!("unbroken not set");
+
+fn main() {
+}