diff options
Diffstat (limited to 'src/libsyntax/ext/format.rs')
| -rw-r--r-- | src/libsyntax/ext/format.rs | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/src/libsyntax/ext/format.rs b/src/libsyntax/ext/format.rs index 31befed6c0c..943279d2dc6 100644 --- a/src/libsyntax/ext/format.rs +++ b/src/libsyntax/ext/format.rs @@ -735,8 +735,10 @@ pub fn expand_args(ecx: @ExtCtxt, sp: Span, (_, None) => { return MRExpr(ecx.expr_uint(sp, 2)); } }; cx.fmtsp = efmt.span; - let (fmt, _fmt_str_style) = expr_to_str(ecx, efmt, - "format argument must be a string literal."); + // Be sure to recursively expand macros just in case the format string uses + // a macro to build the format expression. + let (fmt, _) = expr_to_str(ecx, ecx.expand_expr(efmt), + "format argument must be a string literal."); let mut err = false; do parse::parse_error::cond.trap(|m| { |