Fix "new trace_macros doesn't work if there's an error during expansion"

src/libsyntax/ext/base.rs

@@ -792,14 +792,16 @@ impl<'a> ExtCtxt<'a> {
     pub fn span_bug(&self, sp: Span, msg: &str) -> ! {
         self.parse_sess.span_diagnostic.span_bug(sp, msg);
     }
-    pub fn trace_macros_diag(&self) {
+    pub fn trace_macros_diag(&mut self) {
         for (sp, notes) in self.expansions.iter() {
             let mut db = self.parse_sess.span_diagnostic.span_note_diag(*sp, "trace_macro");
             for note in notes {
                 db.note(note);
             }
             db.emit();
         }
+        // Fixme: does this result in errors?
+        self.expansions.clear();
     }
     pub fn bug(&self, msg: &str) -> ! {
         self.parse_sess.span_diagnostic.bug(msg);

src/libsyntax/ext/expand.rs

@@ -384,13 +384,14 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
         if self.cx.current_expansion.depth > self.cx.ecfg.recursion_limit {
             let info = self.cx.current_expansion.mark.expn_info().unwrap();
             let suggested_limit = self.cx.ecfg.recursion_limit * 2;
-            let mut err = self.cx.struct_span_fatal(info.call_site,
+            let mut err = self.cx.struct_span_err(info.call_site,
                 &format!("recursion limit reached while expanding the macro `{}`",
                          info.callee.name()));
             err.help(&format!(
                 "consider adding a `#![recursion_limit=\"{}\"]` attribute to your crate",
                 suggested_limit));
             err.emit();
+            self.cx.trace_macros_diag();
             panic!(FatalError);
         }
 
@@ -439,11 +440,13 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
             }
             ProcMacroDerive(..) | BuiltinDerive(..) => {
                 self.cx.span_err(attr.span, &format!("`{}` is a derive mode", attr.path));
+                self.cx.trace_macros_diag();
                 kind.dummy(attr.span)
             }
             _ => {
                 let msg = &format!("macro `{}` may not be used in attributes", attr.path);
                 self.cx.span_err(attr.span, msg);
+                self.cx.trace_macros_diag();
                 kind.dummy(attr.span)
             }
         }
@@ -482,6 +485,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                 if let Err(msg) = validate_and_set_expn_info(def_span.map(|(_, s)| s),
                                                              false, false) {
                     self.cx.span_err(path.span, &msg);
+                    self.cx.trace_macros_diag();
                     return kind.dummy(span);
                 }
                 kind.make_from(expand.expand(self.cx, span, mac.node.stream()))
@@ -497,6 +501,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                                                              allow_internal_unstable,
                                                              allow_internal_unsafe) {
                     self.cx.span_err(path.span, &msg);
+                    self.cx.trace_macros_diag();
                     return kind.dummy(span);
                 }
                 kind.make_from(expander.expand(self.cx, span, mac.node.stream()))
@@ -506,6 +511,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                 if ident.name == keywords::Invalid.name() {
                     self.cx.span_err(path.span,
                                     &format!("macro {}! expects an ident argument", path));
+                    self.cx.trace_macros_diag();
                     return kind.dummy(span);
                 };
 
@@ -526,11 +532,13 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
             MultiDecorator(..) | MultiModifier(..) | AttrProcMacro(..) => {
                 self.cx.span_err(path.span,
                                  &format!("`{}` can only be used in attributes", path));
+                self.cx.trace_macros_diag();
                 return kind.dummy(span);
             }
 
             ProcMacroDerive(..) | BuiltinDerive(..) => {
                 self.cx.span_err(path.span, &format!("`{}` is a derive mode", path));
+                self.cx.trace_macros_diag();
                 return kind.dummy(span);
             }
 
@@ -539,6 +547,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                     let msg =
                         format!("macro {}! expects no ident argument, given '{}'", path, ident);
                     self.cx.span_err(path.span, &msg);
+                    self.cx.trace_macros_diag();
                     return kind.dummy(span);
                 }
 
@@ -564,6 +573,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
             let msg = format!("non-{kind} macro in {kind} position: {name}",
                               name = path.segments[0].identifier.name, kind = kind.name());
             self.cx.span_err(path.span, &msg);
+            self.cx.trace_macros_diag();
             kind.dummy(span)
         })
     }
@@ -617,6 +627,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
             _ => {
                 let msg = &format!("macro `{}` may not be used for derive attributes", attr.path);
                 self.cx.span_err(span, msg);
+                self.cx.trace_macros_diag();
                 kind.dummy(span)
             }
         }
@@ -629,6 +640,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
             Ok(expansion) => expansion,
             Err(mut err) => {
                 err.emit();
+                self.cx.trace_macros_diag();
                 return kind.dummy(span);
             }
         };
@@ -739,6 +751,7 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
         if !traits.is_empty() &&
            (kind == ExpansionKind::TraitItems || kind == ExpansionKind::ImplItems) {
             self.cx.span_err(traits[0].span, "`derive` can be only be applied to items");
+            self.cx.trace_macros_diag();
             return kind.expect_from_annotatables(::std::iter::once(item));
         }
         self.collect(kind, InvocationKind::Attr { attr: attr, traits: traits, item: item })

src/libsyntax/ext/tt/macro_rules.rs

@@ -172,7 +172,9 @@ fn generic_extension<'cx>(cx: &'cx mut ExtCtxt,
     }
 
     let best_fail_msg = parse_failure_msg(best_fail_tok.expect("ran no matchers"));
-    cx.span_fatal(best_fail_spot.substitute_dummy(sp), &best_fail_msg);
+    cx.span_err(best_fail_spot.substitute_dummy(sp), &best_fail_msg);
+    cx.trace_macros_diag();
+    DummyResult::any(sp)
 }
 
 // Note that macro-by-example's input is also matched against a token tree:

src/test/ui/macros/assert_eq_trailing_comma.stderr

@@ -4,3 +4,5 @@ error: unexpected end of macro invocation
 12 |     assert_eq!(1, 1,);
    |                    ^
 
+error: aborting due to previous error
+

src/test/ui/macros/assert_ne_trailing_comma.stderr

@@ -4,3 +4,5 @@ error: unexpected end of macro invocation
 12 |     assert_ne!(1, 2,);
    |                    ^
 
+error: aborting due to previous error
+

src/test/ui/macros/trace_faulty_macros.rs

@@ -0,0 +1,55 @@
+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// compile-flags: -Z trace-macros
+
+#![recursion_limit="4"]
+
+macro_rules! my_faulty_macro {
+    () => {
+        my_faulty_macro!(bcd);
+    };
+}
+
+macro_rules! pat_macro {
+    () => {
+        pat_macro!(A{a:a, b:0, c:_, ..});
+    };
+    ($a:pat) => {
+        $a
+    };
+}
+
+macro_rules! my_recursive_macro {
+    () => {
+        my_recursive_macro!();
+    };
+}
+
+macro_rules! my_macro {
+    () => {
+
+    };
+}
+
+fn main() {
+    my_faulty_macro!();
+    my_recursive_macro!();
+    test!();
+    non_exisiting!();
+    derive!(Debug);
+    let a = pat_macro!();
+}
+
+#[my_macro]
+fn use_bang_macro_as_attr(){}
+
+#[derive(Debug)]
+fn use_derive_macro_as_attr(){}

src/test/ui/macros/trace_faulty_macros.stderr

@@ -0,0 +1,47 @@
+error: no rules expected the token `bcd`
+  --> $DIR/trace_faulty_macros.rs:17:26
+   |
+17 |         my_faulty_macro!(bcd);
+   |                          ^^^
+...
+43 |     my_faulty_macro!();
+   |     ------------------- in this macro invocation
+
+note: trace_macro
+  --> $DIR/trace_faulty_macros.rs:43:5
+   |
+43 |     my_faulty_macro!();
+   |     ^^^^^^^^^^^^^^^^^^^
+   |
+   = note: expanding `my_faulty_macro! {  }`
+   = note: to `my_faulty_macro ! ( bcd ) ;`
+   = note: expanding `my_faulty_macro! { bcd }`
+
+error: recursion limit reached while expanding the macro `my_recursive_macro`
+  --> $DIR/trace_faulty_macros.rs:32:9
+   |
+32 |         my_recursive_macro!();
+   |         ^^^^^^^^^^^^^^^^^^^^^^
+...
+44 |     my_recursive_macro!();
+   |     ---------------------- in this macro invocation
+   |
+   = help: consider adding a `#![recursion_limit="8"]` attribute to your crate
+
+note: trace_macro
+  --> $DIR/trace_faulty_macros.rs:44:5
+   |
+44 |     my_recursive_macro!();
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: expanding `my_recursive_macro! {  }`
+   = note: to `my_recursive_macro ! (  ) ;`
+   = note: expanding `my_recursive_macro! {  }`
+   = note: to `my_recursive_macro ! (  ) ;`
+   = note: expanding `my_recursive_macro! {  }`
+   = note: to `my_recursive_macro ! (  ) ;`
+   = note: expanding `my_recursive_macro! {  }`
+   = note: to `my_recursive_macro ! (  ) ;`
+   = note: expanding `my_recursive_macro! {  }`
+   = note: to `my_recursive_macro ! (  ) ;`
+