diff options
Diffstat (limited to 'src/libsyntax/ext/format.rs')
| -rw-r--r-- | src/libsyntax/ext/format.rs | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/src/libsyntax/ext/format.rs b/src/libsyntax/ext/format.rs index 1d99a475b32..513bbf6c77b 100644 --- a/src/libsyntax/ext/format.rs +++ b/src/libsyntax/ext/format.rs @@ -17,6 +17,7 @@ use ext::base::*; use ext::base; use ext::build::AstBuilder; use fmt_macros as parse; +use fold::Folder; use parse::token::special_idents; use parse::token; use ptr::P; @@ -649,6 +650,10 @@ pub fn expand_preparsed_format_args(ecx: &mut ExtCtxt, sp: Span, names: HashMap<String, P<ast::Expr>>) -> P<ast::Expr> { let arg_types: Vec<_> = (0..args.len()).map(|_| None).collect(); + // Expand the format literal so that efmt.span will have a backtrace. This + // is essential for locating a bug when the format literal is generated in + // a macro. (e.g. println!("{}"), which uses concat!($fmt, "\n")). + let efmt = ecx.expander().fold_expr(efmt); let mut cx = Context { ecx: ecx, args: args, @@ -663,9 +668,8 @@ pub fn expand_preparsed_format_args(ecx: &mut ExtCtxt, sp: Span, pieces: Vec::new(), str_pieces: Vec::new(), all_pieces_simple: true, - fmtsp: sp, + fmtsp: efmt.span, }; - cx.fmtsp = efmt.span; let fmt = match expr_to_string(cx.ecx, efmt, "format argument must be a string literal.") { |