Source map cleanups

compiler/rustc_expand/src/proc_macro.rs

@@ -54,7 +54,7 @@ impl base::BangProcMacro for BangProcMacro {
     ) -> Result<TokenStream, ErrorGuaranteed> {
         let _timer =
             ecx.sess.prof.generic_activity_with_arg_recorder("expand_proc_macro", |recorder| {
-                recorder.record_arg_with_span(ecx.expansion_descr(), span);
+                recorder.record_arg_with_span(ecx.sess.source_map(), ecx.expansion_descr(), span);
             });
 
         let proc_macro_backtrace = ecx.ecfg.proc_macro_backtrace;
@@ -85,7 +85,7 @@ impl base::AttrProcMacro for AttrProcMacro {
     ) -> Result<TokenStream, ErrorGuaranteed> {
         let _timer =
             ecx.sess.prof.generic_activity_with_arg_recorder("expand_proc_macro", |recorder| {
-                recorder.record_arg_with_span(ecx.expansion_descr(), span);
+                recorder.record_arg_with_span(ecx.sess.source_map(), ecx.expansion_descr(), span);
             });
 
         let proc_macro_backtrace = ecx.ecfg.proc_macro_backtrace;
@@ -134,7 +134,11 @@ impl MultiItemModifier for DeriveProcMacro {
         let stream = {
             let _timer =
                 ecx.sess.prof.generic_activity_with_arg_recorder("expand_proc_macro", |recorder| {
-                    recorder.record_arg_with_span(ecx.expansion_descr(), span);
+                    recorder.record_arg_with_span(
+                        ecx.sess.source_map(),
+                        ecx.expansion_descr(),
+                        span,
+                    );
                 });
             let proc_macro_backtrace = ecx.ecfg.proc_macro_backtrace;
             let strategy = exec_strategy(ecx);

compiler/rustc_interface/src/interface.rs

@@ -292,7 +292,7 @@ pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Se
                 override_queries: config.override_queries,
             };
 
-            rustc_span::with_source_map(compiler.sess.parse_sess.clone_source_map(), move || {
+            rustc_span::set_source_map(compiler.sess.parse_sess.clone_source_map(), move || {
                 let r = {
                     let _sess_abort_error = OnDrop(|| {
                         compiler.sess.finish_diagnostics(registry);

compiler/rustc_span/src/lib.rs

@@ -87,6 +87,14 @@ pub struct SessionGlobals {
     symbol_interner: symbol::Interner,
     span_interner: Lock<span_encoding::SpanInterner>,
     hygiene_data: Lock<hygiene::HygieneData>,
+
+    /// A reference to the source map in the `Session`. It's an `Option`
+    /// because it can't be initialized until `Session` is created, which
+    /// happens after `SessionGlobals`. `set_source_map` does the
+    /// initialization.
+    ///
+    /// This field should only be used in places where the `Session` is truly
+    /// not available, such as `<Span as Debug>::fmt`.
     source_map: Lock<Option<Lrc<SourceMap>>>,
 }
 
@@ -1013,16 +1021,9 @@ impl<D: Decoder> Decodable<D> for Span {
     }
 }
 
-/// Calls the provided closure, using the provided `SourceMap` to format
-/// any spans that are debug-printed during the closure's execution.
-///
-/// Normally, the global `TyCtxt` is used to retrieve the `SourceMap`
-/// (see `rustc_interface::callbacks::span_debug1`). However, some parts
-/// of the compiler (e.g. `rustc_parse`) may debug-print `Span`s before
-/// a `TyCtxt` is available. In this case, we fall back to
-/// the `SourceMap` provided to this function. If that is not available,
-/// we fall back to printing the raw `Span` field values.
-pub fn with_source_map<T, F: FnOnce() -> T>(source_map: Lrc<SourceMap>, f: F) -> T {
+/// Insert `source_map` into the session globals for the duration of the
+/// closure's execution.
+pub fn set_source_map<T, F: FnOnce() -> T>(source_map: Lrc<SourceMap>, f: F) -> T {
     with_session_globals(|session_globals| {
         *session_globals.source_map.borrow_mut() = Some(source_map);
     });
@@ -1041,6 +1042,8 @@ pub fn with_source_map<T, F: FnOnce() -> T>(source_map: Lrc<SourceMap>, f: F) ->
 
 impl fmt::Debug for Span {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        // Use the global `SourceMap` to print the span. If that's not
+        // available, fall back to printing the raw values.
         with_session_globals(|session_globals| {
             if let Some(source_map) = &*session_globals.source_map.borrow() {
                 write!(f, "{} ({:?})", source_map.span_to_diagnostic_string(*self), self.ctxt())

compiler/rustc_span/src/profiling.rs

@@ -1,3 +1,5 @@
+use crate::source_map::SourceMap;
+
 use std::borrow::Borrow;
 
 use rustc_data_structures::profiling::EventArgRecorder;
@@ -11,25 +13,17 @@ pub trait SpannedEventArgRecorder {
     ///
     /// Note: when self-profiling with costly event arguments, at least one argument
     /// needs to be recorded. A panic will be triggered if that doesn't happen.
-    fn record_arg_with_span<A>(&mut self, event_arg: A, span: crate::Span)
+    fn record_arg_with_span<A>(&mut self, source_map: &SourceMap, event_arg: A, span: crate::Span)
     where
         A: Borrow<str> + Into<String>;
 }
 
 impl SpannedEventArgRecorder for EventArgRecorder<'_> {
-    fn record_arg_with_span<A>(&mut self, event_arg: A, span: crate::Span)
+    fn record_arg_with_span<A>(&mut self, source_map: &SourceMap, event_arg: A, span: crate::Span)
     where
         A: Borrow<str> + Into<String>,
     {
         self.record_arg(event_arg);
-
-        let span_arg = crate::with_session_globals(|session_globals| {
-            if let Some(source_map) = &*session_globals.source_map.borrow() {
-                source_map.span_to_embeddable_string(span)
-            } else {
-                format!("{span:?}")
-            }
-        });
-        self.record_arg(span_arg);
+        self.record_arg(source_map.span_to_embeddable_string(span));
     }
 }