Point at unused arguments for format string

src/libsyntax/ext/base.rs

@@ -13,7 +13,7 @@ pub use self::SyntaxExtension::*;
 use ast::{self, Attribute, Name, PatKind, MetaItem};
 use attr::HasAttrs;
 use codemap::{self, CodeMap, Spanned, respan};
-use syntax_pos::{Span, DUMMY_SP};
+use syntax_pos::{Span, MultiSpan, DUMMY_SP};
 use errors::DiagnosticBuilder;
 use ext::expand::{self, Expansion, Invocation};
 use ext::hygiene::{Mark, SyntaxContext};
@@ -754,22 +754,22 @@ impl<'a> ExtCtxt<'a> {
         last_macro
     }
 
-    pub fn struct_span_warn(&self,
-                            sp: Span,
-                            msg: &str)
-                            -> DiagnosticBuilder<'a> {
+    pub fn struct_span_warn<S: Into<MultiSpan>>(&self,
+                                                sp: S,
+                                                msg: &str)
+                                                -> DiagnosticBuilder<'a> {
         self.parse_sess.span_diagnostic.struct_span_warn(sp, msg)
     }
-    pub fn struct_span_err(&self,
-                           sp: Span,
-                           msg: &str)
-                           -> DiagnosticBuilder<'a> {
+    pub fn struct_span_err<S: Into<MultiSpan>>(&self,
+                                               sp: S,
+                                               msg: &str)
+                                               -> DiagnosticBuilder<'a> {
         self.parse_sess.span_diagnostic.struct_span_err(sp, msg)
     }
-    pub fn struct_span_fatal(&self,
-                             sp: Span,
-                             msg: &str)
-                             -> DiagnosticBuilder<'a> {
+    pub fn struct_span_fatal<S: Into<MultiSpan>>(&self,
+                                                 sp: S,
+                                                 msg: &str)
+                                                 -> DiagnosticBuilder<'a> {
         self.parse_sess.span_diagnostic.struct_span_fatal(sp, msg)
     }
 
@@ -785,7 +785,7 @@ impl<'a> ExtCtxt<'a> {
     ///   in most cases one can construct a dummy expression/item to
     ///   substitute; we never hit resolve/type-checking so the dummy
     ///   value doesn't have to match anything)
-    pub fn span_fatal(&self, sp: Span, msg: &str) -> ! {
+    pub fn span_fatal<S: Into<MultiSpan>>(&self, sp: S, msg: &str) -> ! {
         panic!(self.parse_sess.span_diagnostic.span_fatal(sp, msg));
     }
 
@@ -794,20 +794,20 @@ impl<'a> ExtCtxt<'a> {
     ///
     /// Compilation will be stopped in the near future (at the end of
     /// the macro expansion phase).
-    pub fn span_err(&self, sp: Span, msg: &str) {
+    pub fn span_err<S: Into<MultiSpan>>(&self, sp: S, msg: &str) {
         self.parse_sess.span_diagnostic.span_err(sp, msg);
     }
-    pub fn mut_span_err(&self, sp: Span, msg: &str)
+    pub fn mut_span_err<S: Into<MultiSpan>>(&self, sp: S, msg: &str)
                         -> DiagnosticBuilder<'a> {
         self.parse_sess.span_diagnostic.mut_span_err(sp, msg)
     }
-    pub fn span_warn(&self, sp: Span, msg: &str) {
+    pub fn span_warn<S: Into<MultiSpan>>(&self, sp: S, msg: &str) {
         self.parse_sess.span_diagnostic.span_warn(sp, msg);
     }
-    pub fn span_unimpl(&self, sp: Span, msg: &str) -> ! {
+    pub fn span_unimpl<S: Into<MultiSpan>>(&self, sp: S, msg: &str) -> ! {
         self.parse_sess.span_diagnostic.span_unimpl(sp, msg);
     }
-    pub fn span_bug(&self, sp: Span, msg: &str) -> ! {
+    pub fn span_bug<S: Into<MultiSpan>>(&self, sp: S, msg: &str) -> ! {
         self.parse_sess.span_diagnostic.span_bug(sp, msg);
     }
     pub fn trace_macros_diag(&mut self) {

src/libsyntax/parse/parser.rs

@@ -42,7 +42,7 @@ use ast::{BinOpKind, UnOp};
 use ast::{RangeEnd, RangeSyntax};
 use {ast, attr};
 use codemap::{self, CodeMap, Spanned, respan};
-use syntax_pos::{self, Span, BytePos, FileName, DUMMY_SP};
+use syntax_pos::{self, Span, MultiSpan, BytePos, FileName, DUMMY_SP};
 use errors::{self, DiagnosticBuilder};
 use parse::{self, classify, token};
 use parse::common::SeqSep;
@@ -447,7 +447,9 @@ pub enum Error {
 }
 
 impl Error {
-    pub fn span_err(self, sp: Span, handler: &errors::Handler) -> DiagnosticBuilder {
+    pub fn span_err<S: Into<MultiSpan>>(self,
+                                        sp: S,
+                                        handler: &errors::Handler) -> DiagnosticBuilder {
         match self {
             Error::FileNotFoundForModule { ref mod_name,
                                            ref default_path,
@@ -1266,13 +1268,16 @@ impl<'a> Parser<'a> {
     pub fn fatal(&self, m: &str) -> DiagnosticBuilder<'a> {
         self.sess.span_diagnostic.struct_span_fatal(self.span, m)
     }
-    pub fn span_fatal(&self, sp: Span, m: &str) -> DiagnosticBuilder<'a> {
+    pub fn span_fatal<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> DiagnosticBuilder<'a> {
         self.sess.span_diagnostic.struct_span_fatal(sp, m)
     }
-    pub fn span_fatal_err(&self, sp: Span, err: Error) -> DiagnosticBuilder<'a> {
+    pub fn span_fatal_err<S: Into<MultiSpan>>(&self, sp: S, err: Error) -> DiagnosticBuilder<'a> {
         err.span_err(sp, self.diagnostic())
     }
-    pub fn span_fatal_help(&self, sp: Span, m: &str, help: &str) -> DiagnosticBuilder<'a> {
+    pub fn span_fatal_help<S: Into<MultiSpan>>(&self,
+                                            sp: S,
+                                            m: &str,
+                                            help: &str) -> DiagnosticBuilder<'a> {
         let mut err = self.sess.span_diagnostic.struct_span_fatal(sp, m);
         err.help(help);
         err
@@ -1283,21 +1288,21 @@ impl<'a> Parser<'a> {
     pub fn warn(&self, m: &str) {
         self.sess.span_diagnostic.span_warn(self.span, m)
     }
-    pub fn span_warn(&self, sp: Span, m: &str) {
+    pub fn span_warn<S: Into<MultiSpan>>(&self, sp: S, m: &str) {
         self.sess.span_diagnostic.span_warn(sp, m)
     }
-    pub fn span_err(&self, sp: Span, m: &str) {
+    pub fn span_err<S: Into<MultiSpan>>(&self, sp: S, m: &str) {
         self.sess.span_diagnostic.span_err(sp, m)
     }
-    pub fn struct_span_err(&self, sp: Span, m: &str) -> DiagnosticBuilder<'a> {
+    pub fn struct_span_err<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> DiagnosticBuilder<'a> {
         self.sess.span_diagnostic.struct_span_err(sp, m)
     }
-    pub fn span_err_help(&self, sp: Span, m: &str, h: &str) {
+    pub fn span_err_help<S: Into<MultiSpan>>(&self, sp: S, m: &str, h: &str) {
         let mut err = self.sess.span_diagnostic.mut_span_err(sp, m);
         err.help(h);
         err.emit();
     }
-    pub fn span_bug(&self, sp: Span, m: &str) -> ! {
+    pub fn span_bug<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> ! {
         self.sess.span_diagnostic.span_bug(sp, m)
     }
     pub fn abort_if_errors(&self) {

src/libsyntax_ext/format.rs

@@ -814,15 +814,11 @@ pub fn expand_preparsed_format_args(ecx: &mut ExtCtxt,
                 let (sp, msg) = errs.into_iter().next().unwrap();
                 cx.ecx.struct_span_err(sp, msg)
             } else {
-                let mut diag = cx.ecx.struct_span_err(cx.fmtsp,
-                    "multiple unused formatting arguments");
-
-                // Ignoring message, as it gets repetitive
-                // Then use MultiSpan to not clutter up errors
-                for (sp, _) in errs {
-                    diag.span_label(sp, "unused");
-                }
-
+                let mut diag = cx.ecx.struct_span_err(
+                    errs.iter().map(|&(sp, _)| sp).collect::<Vec<Span>>(),
+                    "multiple unused formatting arguments"
+                );
+                diag.span_label(cx.fmtsp, "multiple unused arguments in this statement");
                 diag
             }
         };

src/test/ui/macros/format-foreign.rs

@@ -9,7 +9,7 @@
 // except according to those terms.
 
 fn main() {
-    println!("%.*3$s %s!\n", "Hello,", "World", 4);
+    println!("%.*3$s %s!\n", "Hello,", "World", 4); //~ ERROR multiple unused formatting arguments
     println!("%1$*2$.*3$f", 123.456); //~ ERROR never used
 
     // This should *not* produce hints, on the basis that there's equally as

src/test/ui/macros/format-foreign.stderr

@@ -1,12 +1,8 @@
 error: multiple unused formatting arguments
-  --> $DIR/format-foreign.rs:12:5
+  --> $DIR/format-foreign.rs:12:30
    |
-12 |     println!("%.*3$s %s!/n", "Hello,", "World", 4);
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^--------^^-------^^-^^
-   |                              |         |        |
-   |                              |         |        unused
-   |                              |         unused
-   |                              unused
+12 |     println!("%.*3$s %s!/n", "Hello,", "World", 4); //~ ERROR multiple unused formatting arguments
+   |     -------------------------^^^^^^^^--^^^^^^^--^-- multiple unused arguments in this statement
    |
    = help: `%.*3$s` should be written as `{:.2$}`
    = help: `%s` should be written as `{}`

src/test/ui/macros/format-unused-lables.rs

@@ -10,17 +10,18 @@
 
 fn main() {
     println!("Test", 123, 456, 789);
+    //~^ ERROR multiple unused formatting arguments
 
     println!("Test2",
-        123,
+        123,  //~ ERROR multiple unused formatting arguments
         456,
         789
     );
 
     println!("Some stuff", UNUSED="args"); //~ ERROR named argument never used
 
     println!("Some more $STUFF",
-        "woo!",
+        "woo!",  //~ ERROR multiple unused formatting arguments
             STUFF=
        "things"
              , UNUSED="args");

src/test/ui/macros/format-unused-lables.stderr

@@ -1,49 +1,43 @@
 error: multiple unused formatting arguments
-  --> $DIR/format-unused-lables.rs:12:5
+  --> $DIR/format-unused-lables.rs:12:22
    |
 12 |     println!("Test", 123, 456, 789);
-   |     ^^^^^^^^^^^^^^^^^---^^---^^---^^
-   |                      |    |    |
-   |                      |    |    unused
-   |                      |    unused
-   |                      unused
+   |     -----------------^^^--^^^--^^^-- multiple unused arguments in this statement
    |
    = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
 
 error: multiple unused formatting arguments
-  --> $DIR/format-unused-lables.rs:14:5
+  --> $DIR/format-unused-lables.rs:16:9
    |
-14 | /     println!("Test2",
-15 | |         123,
-   | |         --- unused
-16 | |         456,
-   | |         --- unused
-17 | |         789
-   | |         --- unused
-18 | |     );
-   | |______^
+15 | /     println!("Test2",
+16 | |         123,  //~ ERROR multiple unused formatting arguments
+   | |         ^^^
+17 | |         456,
+   | |         ^^^
+18 | |         789
+   | |         ^^^
+19 | |     );
+   | |______- multiple unused arguments in this statement
    |
    = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
 
 error: named argument never used
-  --> $DIR/format-unused-lables.rs:20:35
+  --> $DIR/format-unused-lables.rs:21:35
    |
-20 |     println!("Some stuff", UNUSED="args"); //~ ERROR named argument never used
+21 |     println!("Some stuff", UNUSED="args"); //~ ERROR named argument never used
    |                                   ^^^^^^
 
 error: multiple unused formatting arguments
-  --> $DIR/format-unused-lables.rs:22:5
+  --> $DIR/format-unused-lables.rs:24:9
    |
-22 | /     println!("Some more $STUFF",
-23 | |         "woo!",
-   | |         ------ unused
-24 | |             STUFF=
-25 | |        "things"
-   | |        -------- unused
-26 | |              , UNUSED="args");
-   | |_______________________------_^
-   |                         |
-   |                         unused
+23 | /     println!("Some more $STUFF",
+24 | |         "woo!",  //~ ERROR multiple unused formatting arguments
+   | |         ^^^^^^
+25 | |             STUFF=
+26 | |        "things"
+   | |        ^^^^^^^^
+27 | |              , UNUSED="args");
+   | |_______________________^^^^^^_- multiple unused arguments in this statement
    |
    = help: `$STUFF` should be written as `{STUFF}`
    = note: shell formatting not supported; see the documentation for `std::fmt`