auto merge of #10844 : huonw/rust/deriving-expn-info, r=alexcrichton

Previously something like

    struct NotEq;

    #[deriving(Eq)]
    struct Error {
        foo: NotEq
    }

would just point to the `foo` field, with no mention of the
`deriving(Eq)`. With this patch, the compiler creates a note saying "in
expansion of #[deriving(Eq)]" pointing to the Eq.

(includes some cleanup/preparation; the commit view might be nicer, to filter out the noise of the first one.)

Author: bors

src/librustc/front/test.rs

@@ -18,7 +18,7 @@ use std::vec;
 use syntax::ast_util::*;
 use syntax::attr::AttrMetaMethods;
 use syntax::attr;
-use syntax::codemap::{dummy_sp, Span, ExpnInfo, NameAndSpan};
+use syntax::codemap::{dummy_sp, Span, ExpnInfo, NameAndSpan, MacroAttribute};
 use syntax::codemap;
 use syntax::ext::base::ExtCtxt;
 use syntax::fold::ast_fold;
@@ -158,6 +158,7 @@ fn generate_test_harness(sess: session::Session, crate: ast::Crate)
         call_site: dummy_sp(),
         callee: NameAndSpan {
             name: @"test",
+            format: MacroAttribute,
             span: None
         }
     });

src/libsyntax/codemap.rs

@@ -161,8 +161,22 @@ pub struct LocWithOpt {
 // used to be structural records. Better names, anyone?
 pub struct FileMapAndLine {fm: @FileMap, line: uint}
 pub struct FileMapAndBytePos {fm: @FileMap, pos: BytePos}
+
 #[deriving(IterBytes)]
-pub struct NameAndSpan {name: @str, span: Option<Span>}
+pub enum MacroFormat {
+    // e.g. #[deriving(...)] <item>
+    MacroAttribute,
+    // e.g. `format!()`
+    MacroBang
+}
+
+#[deriving(IterBytes)]
+pub struct NameAndSpan {
+    name: @str,
+    // the format with which the macro was invoked.
+    format: MacroFormat,
+    span: Option<Span>
+}
 
 /// Extra information for tracking macro expansion of spans
 #[deriving(IterBytes)]

src/libsyntax/diagnostic.rs

@@ -342,8 +342,13 @@ fn highlight_lines(cm: @codemap::CodeMap,
 fn print_macro_backtrace(cm: @codemap::CodeMap, sp: Span) {
     for ei in sp.expn_info.iter() {
         let ss = ei.callee.span.as_ref().map_default(~"", |span| cm.span_to_str(*span));
+        let (pre, post) = match ei.callee.format {
+            codemap::MacroAttribute => ("#[", "]"),
+            codemap::MacroBang => ("", "!")
+        };
+
         print_diagnostic(ss, note,
-                         format!("in expansion of {}!", ei.callee.name));
+                         format!("in expansion of {}{}{}", pre, ei.callee.name, post));
         let ss = cm.span_to_str(ei.call_site);
         print_diagnostic(ss, note, "expansion site");
         print_macro_backtrace(cm, ei.call_site);

src/libsyntax/ext/deriving/clone.rs

@@ -20,6 +20,8 @@ pub fn expand_deriving_clone(cx: @ExtCtxt,
                              in_items: ~[@item])
                           -> ~[@item] {
     let trait_def = TraitDef {
+        cx: cx, span: span,
+
         path: Path::new(~["std", "clone", "Clone"]),
         additional_bounds: ~[],
         generics: LifetimeBounds::empty(),
@@ -37,7 +39,7 @@ pub fn expand_deriving_clone(cx: @ExtCtxt,
         ]
     };
 
-    trait_def.expand(cx, span, mitem, in_items)
+    trait_def.expand(mitem, in_items)
 }
 
 pub fn expand_deriving_deep_clone(cx: @ExtCtxt,
@@ -46,6 +48,8 @@ pub fn expand_deriving_deep_clone(cx: @ExtCtxt,
                                   in_items: ~[@item])
     -> ~[@item] {
     let trait_def = TraitDef {
+        cx: cx, span: span,
+
         path: Path::new(~["std", "clone", "DeepClone"]),
         additional_bounds: ~[],
         generics: LifetimeBounds::empty(),
@@ -65,7 +69,7 @@ pub fn expand_deriving_deep_clone(cx: @ExtCtxt,
         ]
     };
 
-    trait_def.expand(cx, span, mitem, in_items)
+    trait_def.expand(mitem, in_items)
 }
 
 fn cs_clone(

src/libsyntax/ext/deriving/cmp/eq.rs

@@ -45,6 +45,8 @@ pub fn expand_deriving_eq(cx: @ExtCtxt,
     );
 
     let trait_def = TraitDef {
+        cx: cx, span: span,
+
         path: Path::new(~["std", "cmp", "Eq"]),
         additional_bounds: ~[],
         generics: LifetimeBounds::empty(),
@@ -53,5 +55,5 @@ pub fn expand_deriving_eq(cx: @ExtCtxt,
             md!("ne", cs_ne)
         ]
     };
-    trait_def.expand(cx, span, mitem, in_items)
+    trait_def.expand(mitem, in_items)
 }

src/libsyntax/ext/deriving/cmp/ord.rs

@@ -35,6 +35,8 @@ pub fn expand_deriving_ord(cx: @ExtCtxt,
     );
 
     let trait_def = TraitDef {
+        cx: cx, span: span,
+
         path: Path::new(~["std", "cmp", "Ord"]),
         additional_bounds: ~[],
         generics: LifetimeBounds::empty(),
@@ -45,7 +47,7 @@ pub fn expand_deriving_ord(cx: @ExtCtxt,
             md!("ge", false, true)
         ]
     };
-    trait_def.expand(cx, span, mitem, in_items)
+    trait_def.expand(mitem, in_items)
 }
 
 /// Strict inequality.

src/libsyntax/ext/deriving/cmp/totaleq.rs

@@ -24,6 +24,8 @@ pub fn expand_deriving_totaleq(cx: @ExtCtxt,
     }
 
     let trait_def = TraitDef {
+        cx: cx, span: span,
+
         path: Path::new(~["std", "cmp", "TotalEq"]),
         additional_bounds: ~[],
         generics: LifetimeBounds::empty(),
@@ -40,5 +42,5 @@ pub fn expand_deriving_totaleq(cx: @ExtCtxt,
             }
         ]
     };
-    trait_def.expand(cx, span, mitem, in_items)
+    trait_def.expand(mitem, in_items)
 }

src/libsyntax/ext/deriving/cmp/totalord.rs

@@ -21,6 +21,8 @@ pub fn expand_deriving_totalord(cx: @ExtCtxt,
                                 mitem: @MetaItem,
                                 in_items: ~[@item]) -> ~[@item] {
     let trait_def = TraitDef {
+        cx: cx, span: span,
+
         path: Path::new(~["std", "cmp", "TotalOrd"]),
         additional_bounds: ~[],
         generics: LifetimeBounds::empty(),
@@ -38,7 +40,7 @@ pub fn expand_deriving_totalord(cx: @ExtCtxt,
         ]
     };
 
-    trait_def.expand(cx, span, mitem, in_items)
+    trait_def.expand(mitem, in_items)
 }
 
 

src/libsyntax/ext/deriving/decodable.rs

@@ -24,6 +24,8 @@ pub fn expand_deriving_decodable(cx: @ExtCtxt,
                                  mitem: @MetaItem,
                                  in_items: ~[@item]) -> ~[@item] {
     let trait_def = TraitDef {
+        cx: cx, span: span,
+
         path: Path::new_(~["extra", "serialize", "Decodable"], None,
                          ~[~Literal(Path::new_local("__D"))], true),
         additional_bounds: ~[],
@@ -46,7 +48,7 @@ pub fn expand_deriving_decodable(cx: @ExtCtxt,
         ]
     };
 
-    trait_def.expand(cx, span, mitem, in_items)
+    trait_def.expand(mitem, in_items)
 }
 
 fn decodable_substructure(cx: @ExtCtxt, span: Span,

src/libsyntax/ext/deriving/default.rs

@@ -20,6 +20,8 @@ pub fn expand_deriving_default(cx: @ExtCtxt,
                             in_items: ~[@item])
     -> ~[@item] {
     let trait_def = TraitDef {
+        cx: cx, span: span,
+
         path: Path::new(~["std", "default", "Default"]),
         additional_bounds: ~[],
         generics: LifetimeBounds::empty(),
@@ -36,7 +38,7 @@ pub fn expand_deriving_default(cx: @ExtCtxt,
             },
         ]
     };
-    trait_def.expand(cx, span, mitem, in_items)
+    trait_def.expand(mitem, in_items)
 }
 
 fn default_substructure(cx: @ExtCtxt, span: Span, substr: &Substructure) -> @Expr {