syntax: Make def-site span mandatory in ExpnInfo/MacroBacktrace/DiagnosticSpanMacroExpansion

We have to deal with dummy spans anyway

Remove def-site span from expander interfaces.
It's not used by the expansion infra, only by specific expanders, which can keep it themselves if they want it.

12 files changed, 61 insertions, 77 deletions

diff --git a/src/librustc/hir/lowering.rs b/src/librustc/hir/lowering.rs
index 549c34d961a..c44fd30be85 100644
--- a/src/librustc/hir/lowering.rs
+++ b/src/librustc/hir/lowering.rs
@@ -877,7 +877,7 @@ impl<'a> LoweringContext<'a> {
     ) -> Span {
         let mark = Mark::fresh(Mark::root());
         mark.set_expn_info(ExpnInfo {
-            def_site: Some(span),
+            def_site: span,
             allow_internal_unstable,
             ..ExpnInfo::default(ExpnKind::Desugaring(reason), span, self.sess.edition())
         });
diff --git a/src/librustc/lint/mod.rs b/src/librustc/lint/mod.rs
index 2bf4f1d3cfb..9876d6c1fa5 100644
--- a/src/librustc/lint/mod.rs
+++ b/src/librustc/lint/mod.rs
@@ -888,13 +888,11 @@ pub fn in_external_macro(sess: &Session, span: Span) -> bool {
         ExpnKind::Desugaring(DesugaringKind::ForLoop) => false,
         ExpnKind::Desugaring(_) => true, // well, it's "external"
         ExpnKind::MacroBang(..) => {
-            let def_site = match info.def_site {
-                Some(span) => span,
-                // no span for the def_site means it's an external macro
-                None => return true,
-            };
-
-            match sess.source_map().span_to_snippet(def_site) {
+            if info.def_site.is_dummy() {
+                // dummy span for the def_site means it's an external macro
+                return true;
+            }
+            match sess.source_map().span_to_snippet(info.def_site) {
                 Ok(code) => !code.starts_with("macro_rules"),
                 // no snippet = external macro or compiler-builtin expansion
                 Err(_) => true,
diff --git a/src/librustc/traits/error_reporting.rs b/src/librustc/traits/error_reporting.rs
index fb7ed147445..a7dfbd688c1 100644
--- a/src/librustc/traits/error_reporting.rs
+++ b/src/librustc/traits/error_reporting.rs
@@ -61,12 +61,9 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
             // We want to ignore desugarings here: spans are equivalent even
             // if one is the result of a desugaring and the other is not.
             let mut span = error.obligation.cause.span;
-            if let Some(ExpnInfo {
-                kind: ExpnKind::Desugaring(_),
-                def_site: Some(def_span),
-                ..
-            }) = span.ctxt().outer_expn_info() {
-                span = def_span;
+            if let Some(ExpnInfo { kind: ExpnKind::Desugaring(_), def_site, .. })
+                    = span.ctxt().outer_expn_info() {
+                span = def_site;
             }
 
             error_map.entry(span).or_default().push(
diff --git a/src/librustc_errors/emitter.rs b/src/librustc_errors/emitter.rs
index 83a0fb486fd..361b5cd9357 100644
--- a/src/librustc_errors/emitter.rs
+++ b/src/librustc_errors/emitter.rs
@@ -723,39 +723,37 @@ impl EmitterWriter {
                 for (i, trace) in sp.macro_backtrace().iter().rev().enumerate() {
                     // Only show macro locations that are local
                     // and display them like a span_note
-                    if let Some(def_site) = trace.def_site_span {
-                        if def_site.is_dummy() {
-                            continue;
-                        }
-                        if always_backtrace {
-                            new_labels.push((def_site,
-                                             format!("in this expansion of `{}`{}",
-                                                     trace.macro_decl_name,
-                                                     if backtrace_len > 2 {
-                                                         // if backtrace_len == 1 it'll be pointed
-                                                         // at by "in this macro invocation"
-                                                         format!(" (#{})", i + 1)
-                                                     } else {
-                                                         String::new()
-                                                     })));
-                        }
-                        // Check to make sure we're not in any <*macros>
-                        if !sm.span_to_filename(def_site).is_macros() &&
-                           !trace.macro_decl_name.starts_with("desugaring of ") &&
-                           !trace.macro_decl_name.starts_with("#[") ||
-                           always_backtrace {
-                            new_labels.push((trace.call_site,
-                                             format!("in this macro invocation{}",
-                                                     if backtrace_len > 2 && always_backtrace {
-                                                         // only specify order when the macro
-                                                         // backtrace is multiple levels deep
-                                                         format!(" (#{})", i + 1)
-                                                     } else {
-                                                         String::new()
-                                                     })));
-                            if !always_backtrace {
-                                break;
-                            }
+                    if trace.def_site_span.is_dummy() {
+                        continue;
+                    }
+                    if always_backtrace {
+                        new_labels.push((trace.def_site_span,
+                                            format!("in this expansion of `{}`{}",
+                                                    trace.macro_decl_name,
+                                                    if backtrace_len > 2 {
+                                                        // if backtrace_len == 1 it'll be pointed
+                                                        // at by "in this macro invocation"
+                                                        format!(" (#{})", i + 1)
+                                                    } else {
+                                                        String::new()
+                                                    })));
+                    }
+                    // Check to make sure we're not in any <*macros>
+                    if !sm.span_to_filename(trace.def_site_span).is_macros() &&
+                        !trace.macro_decl_name.starts_with("desugaring of ") &&
+                        !trace.macro_decl_name.starts_with("#[") ||
+                        always_backtrace {
+                        new_labels.push((trace.call_site,
+                                            format!("in this macro invocation{}",
+                                                    if backtrace_len > 2 && always_backtrace {
+                                                        // only specify order when the macro
+                                                        // backtrace is multiple levels deep
+                                                        format!(" (#{})", i + 1)
+                                                    } else {
+                                                        String::new()
+                                                    })));
+                        if !always_backtrace {
+                            break;
                         }
                     }
                 }
diff --git a/src/librustc_save_analysis/lib.rs b/src/librustc_save_analysis/lib.rs
index fab2537f9d8..aeaee1887b9 100644
--- a/src/librustc_save_analysis/lib.rs
+++ b/src/librustc_save_analysis/lib.rs
@@ -841,7 +841,6 @@ impl<'l, 'tcx> SaveContext<'l, 'tcx> {
         let callsite = span.source_callsite();
         let callsite_span = self.span_from_span(callsite);
         let callee = span.source_callee()?;
-        let callee_span = callee.def_site?;
 
         // Ignore attribute macros, their spans are usually mangled
         if let ExpnKind::MacroAttribute(_) = callee.kind {
@@ -855,7 +854,7 @@ impl<'l, 'tcx> SaveContext<'l, 'tcx> {
             .sess
             .imported_macro_spans
             .borrow()
-            .get(&callee_span)
+            .get(&callee.def_site)
         {
             let &(ref mac_name, mac_span) = mac;
             let mac_span = self.span_from_span(mac_span);
@@ -866,7 +865,7 @@ impl<'l, 'tcx> SaveContext<'l, 'tcx> {
             });
         }
 
-        let callee_span = self.span_from_span(callee_span);
+        let callee_span = self.span_from_span(callee.def_site);
         Some(MacroRef {
             span: callsite_span,
             qualname: callee.kind.descr().to_string(), // FIXME: generate the real qualname
diff --git a/src/libsyntax/ext/base.rs b/src/libsyntax/ext/base.rs
index 267046655ff..2f8d6f00ba7 100644
--- a/src/libsyntax/ext/base.rs
+++ b/src/libsyntax/ext/base.rs
@@ -219,7 +219,6 @@ pub trait TTMacroExpander {
         ecx: &'cx mut ExtCtxt<'_>,
         span: Span,
         input: TokenStream,
-        def_span: Option<Span>,
     ) -> Box<dyn MacResult+'cx>;
 }
 
@@ -236,7 +235,6 @@ impl<F> TTMacroExpander for F
         ecx: &'cx mut ExtCtxt<'_>,
         span: Span,
         input: TokenStream,
-        _def_span: Option<Span>,
     ) -> Box<dyn MacResult+'cx> {
         struct AvoidInterpolatedIdents;
 
@@ -654,7 +652,7 @@ impl SyntaxExtension {
         ExpnInfo {
             call_site,
             kind: self.expn_kind(Symbol::intern(descr)),
-            def_site: Some(self.span),
+            def_site: self.span,
             default_transparency: self.default_transparency,
             allow_internal_unstable: self.allow_internal_unstable.clone(),
             allow_internal_unsafe: self.allow_internal_unsafe,
diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
index bb7d7352e05..06ff2bc655c 100644
--- a/src/libsyntax/ext/expand.rs
+++ b/src/libsyntax/ext/expand.rs
@@ -673,7 +673,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                 result
             }
             SyntaxExtensionKind::LegacyBang(expander) => {
-                let tok_result = expander.expand(self.cx, span, mac.node.stream(), Some(ext.span));
+                let tok_result = expander.expand(self.cx, span, mac.node.stream());
                 kind.make_from(tok_result)
             }
 
diff --git a/src/libsyntax/ext/tt/macro_rules.rs b/src/libsyntax/ext/tt/macro_rules.rs
index 665c794422d..5c6438a7ef5 100644
--- a/src/libsyntax/ext/tt/macro_rules.rs
+++ b/src/libsyntax/ext/tt/macro_rules.rs
@@ -88,6 +88,7 @@ impl<'a> ParserAnyMacro<'a> {
 
 struct MacroRulesMacroExpander {
     name: ast::Ident,
+    span: Span,
     lhses: Vec<quoted::TokenTree>,
     rhses: Vec<quoted::TokenTree>,
     valid: bool,
@@ -99,12 +100,11 @@ impl TTMacroExpander for MacroRulesMacroExpander {
         cx: &'cx mut ExtCtxt<'_>,
         sp: Span,
         input: TokenStream,
-        def_span: Option<Span>,
     ) -> Box<dyn MacResult + 'cx> {
         if !self.valid {
             return DummyResult::any(sp);
         }
-        generic_extension(cx, sp, def_span, self.name, input, &self.lhses, &self.rhses)
+        generic_extension(cx, sp, self.span, self.name, input, &self.lhses, &self.rhses)
     }
 }
 
@@ -117,7 +117,7 @@ fn trace_macros_note(cx: &mut ExtCtxt<'_>, sp: Span, message: String) {
 fn generic_extension<'cx>(
     cx: &'cx mut ExtCtxt<'_>,
     sp: Span,
-    def_span: Option<Span>,
+    def_span: Span,
     name: ast::Ident,
     arg: TokenStream,
     lhses: &[quoted::TokenTree],
@@ -199,10 +199,8 @@ fn generic_extension<'cx>(
     let span = token.span.substitute_dummy(sp);
     let mut err = cx.struct_span_err(span, &parse_failure_msg(&token));
     err.span_label(span, label);
-    if let Some(sp) = def_span {
-        if cx.source_map().span_to_filename(sp).is_real() && !sp.is_dummy() {
-            err.span_label(cx.source_map().def_span(sp), "when calling this macro");
-        }
+    if !def_span.is_dummy() && cx.source_map().span_to_filename(def_span).is_real() {
+        err.span_label(cx.source_map().def_span(def_span), "when calling this macro");
     }
 
     // Check whether there's a missing comma in this macro call, like `println!("{}" a);`
@@ -377,7 +375,7 @@ pub fn compile(
     }
 
     let expander: Box<_> =
-        Box::new(MacroRulesMacroExpander { name: def.ident, lhses, rhses, valid });
+        Box::new(MacroRulesMacroExpander { name: def.ident, span: def.span, lhses, rhses, valid });
 
     let (default_transparency, transparency_error) =
         attr::find_transparency(&def.attrs, body.legacy);
diff --git a/src/libsyntax/json.rs b/src/libsyntax/json.rs
index 767ab74355e..ec0222d90eb 100644
--- a/src/libsyntax/json.rs
+++ b/src/libsyntax/json.rs
@@ -170,7 +170,7 @@ struct DiagnosticSpanMacroExpansion {
     macro_decl_name: String,
 
     /// span where macro was defined (if known)
-    def_site_span: Option<DiagnosticSpan>,
+    def_site_span: DiagnosticSpan,
 }
 
 #[derive(RustcEncodable)]
@@ -300,14 +300,13 @@ impl DiagnosticSpan {
                                      None,
                                      backtrace,
                                      je);
-            let def_site_span = bt.def_site_span.map(|sp| {
-                Self::from_span_full(sp,
+            let def_site_span =
+                Self::from_span_full(bt.def_site_span,
                                      false,
                                      None,
                                      None,
                                      vec![].into_iter(),
-                                     je)
-            });
+                                     je);
             Box::new(DiagnosticSpanMacroExpansion {
                 span: call_site,
                 macro_decl_name: bt.macro_decl_name,
diff --git a/src/libsyntax_pos/hygiene.rs b/src/libsyntax_pos/hygiene.rs
index f8318f54320..63b692ccdcb 100644
--- a/src/libsyntax_pos/hygiene.rs
+++ b/src/libsyntax_pos/hygiene.rs
@@ -26,7 +26,7 @@
 // trigger runtime aborts. (Fortunately these are obvious and easy to fix.)
 
 use crate::GLOBALS;
-use crate::Span;
+use crate::{Span, DUMMY_SP};
 use crate::edition::Edition;
 use crate::symbol::{kw, Symbol};
 
@@ -632,11 +632,9 @@ pub struct ExpnInfo {
 
     // --- The part specific to the macro/desugaring definition.
     // --- FIXME: Share it between expansions with the same definition.
-    /// The span of the macro definition itself. The macro may not
-    /// have a sensible definition span (e.g., something defined
-    /// completely inside libsyntax) in which case this is None.
+    /// The span of the macro definition (possibly dummy).
     /// This span serves only informational purpose and is not used for resolution.
-    pub def_site: Option<Span>,
+    pub def_site: Span,
     /// Transparency used by `apply_mark` for mark with this expansion info by default.
     pub default_transparency: Transparency,
     /// List of #[unstable]/feature-gated features that the macro is allowed to use
@@ -659,7 +657,7 @@ impl ExpnInfo {
         ExpnInfo {
             call_site,
             kind,
-            def_site: None,
+            def_site: DUMMY_SP,
             default_transparency: Transparency::SemiTransparent,
             allow_internal_unstable: None,
             allow_internal_unsafe: false,
diff --git a/src/libsyntax_pos/lib.rs b/src/libsyntax_pos/lib.rs
index d4c1958f7e2..1369fca3b4a 100644
--- a/src/libsyntax_pos/lib.rs
+++ b/src/libsyntax_pos/lib.rs
@@ -1363,8 +1363,8 @@ pub struct MacroBacktrace {
     /// name of macro that was applied (e.g., "foo!" or "#[derive(Eq)]")
     pub macro_decl_name: String,
 
-    /// span where macro was defined (if known)
-    pub def_site_span: Option<Span>,
+    /// span where macro was defined (possibly dummy)
+    pub def_site_span: Span,
 }
 
 // _____________________________________________________________________________
diff --git a/src/test/run-pass-fulldeps/auxiliary/plugin-args.rs b/src/test/run-pass-fulldeps/auxiliary/plugin-args.rs
index 7cbfef52b4a..36cee82893a 100644
--- a/src/test/run-pass-fulldeps/auxiliary/plugin-args.rs
+++ b/src/test/run-pass-fulldeps/auxiliary/plugin-args.rs
@@ -28,8 +28,7 @@ impl TTMacroExpander for Expander {
     fn expand<'cx>(&self,
                    ecx: &'cx mut ExtCtxt,
                    sp: Span,
-                   _: TokenStream,
-                   _: Option<Span>) -> Box<dyn MacResult+'cx> {
+                   _: TokenStream) -> Box<dyn MacResult+'cx> {
         let args = self.args.iter().map(|i| pprust::meta_list_item_to_string(i))
             .collect::<Vec<_>>().join(", ");
         MacEager::expr(ecx.expr_str(sp, Symbol::intern(&args)))