Add support for embedding pretty printers via the #[debugger_visualizer] attribute. Add tests for embedding pretty printers and update documentation.

Ensure all error checking for `#[debugger_visualizer]` is done up front and not when the `debugger_visualizer` query is run.

Clean up potential ODR violations when embedding pretty printers into the `__rustc_debug_gdb_scripts_section__` section.

Respond to PR comments and update documentation.

compiler/rustc_passes/src/check_attr.rs

@@ -8,6 +8,7 @@ use rustc_ast::tokenstream::DelimSpan;
 use rustc_ast::{ast, AttrStyle, Attribute, Lit, LitKind, MacArgs, MetaItemKind, NestedMetaItem};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::{pluralize, struct_span_err, Applicability, MultiSpan};
+use rustc_expand::base::resolve_path;
 use rustc_feature::{AttributeDuplicates, AttributeType, BuiltinAttribute, BUILTIN_ATTRIBUTE_MAP};
 use rustc_hir as hir;
 use rustc_hir::def_id::{LocalDefId, CRATE_DEF_ID};
@@ -1982,49 +1983,64 @@ impl CheckAttrVisitor<'_> {
             }
         }
 
-        let hints = match attr.meta_item_list() {
-            Some(meta_item_list) => meta_item_list,
-            None => {
-                self.emit_debugger_visualizer_err(attr);
-                return false;
-            }
+        let Some(hints) = attr.meta_item_list() else {
+            self.emit_debugger_visualizer_err(attr.span);
+            return false;
         };
 
         let hint = match hints.len() {
             1 => &hints[0],
             _ => {
-                self.emit_debugger_visualizer_err(attr);
+                self.emit_debugger_visualizer_err(attr.span);
                 return false;
             }
         };
 
-        if !hint.has_name(sym::natvis_file) {
-            self.emit_debugger_visualizer_err(attr);
+        let Some(meta_item) = hint.meta_item() else {
+            self.emit_debugger_visualizer_err(attr.span);
             return false;
-        }
+        };
 
-        let meta_item = match hint.meta_item() {
-            Some(meta_item) => meta_item,
-            None => {
-                self.emit_debugger_visualizer_err(attr);
+        let visualizer_path = match (meta_item.name_or_empty(), meta_item.value_str()) {
+            (sym::natvis_file, Some(value)) => value,
+            (sym::gdb_script_file, Some(value)) => value,
+            (_, _) => {
+                self.emit_debugger_visualizer_err(meta_item.span);
                 return false;
             }
         };
 
-        match (meta_item.name_or_empty(), meta_item.value_str()) {
-            (sym::natvis_file, Some(_)) => true,
-            (_, _) => {
-                self.emit_debugger_visualizer_err(attr);
+        let file =
+            match resolve_path(&self.tcx.sess.parse_sess, visualizer_path.as_str(), attr.span) {
+                Ok(file) => file,
+                Err(mut err) => {
+                    err.emit();
+                    return false;
+                }
+            };
+
+        match std::fs::File::open(&file) {
+            Ok(_) => true,
+            Err(err) => {
+                self.tcx
+                    .sess
+                    .struct_span_err(
+                        meta_item.span,
+                        &format!("couldn't read {}: {}", file.display(), err),
+                    )
+                    .emit();
                 false
             }
         }
     }
 
-    fn emit_debugger_visualizer_err(&self, attr: &Attribute) {
+    fn emit_debugger_visualizer_err(&self, span: Span) {
         self.tcx
             .sess
-            .struct_span_err(attr.span, "invalid argument")
+            .struct_span_err(span, "invalid argument")
             .note(r#"expected: `natvis_file = "..."`"#)
+            .note(r#"OR"#)
+            .note(r#"expected: `gdb_script_file = "..."`"#)
             .emit();
     }
 

compiler/rustc_passes/src/debugger_visualizer.rs

@@ -21,9 +21,8 @@ fn check_for_debugger_visualizer<'tcx>(
     let attrs = tcx.hir().attrs(hir_id);
     for attr in attrs {
         if attr.has_name(sym::debugger_visualizer) {
-            let list = match attr.meta_item_list() {
-                Some(list) => list,
-                _ => continue,
+            let Some(list) = attr.meta_item_list() else {
+                continue
             };
 
             let meta_item = match list.len() {
@@ -34,45 +33,28 @@ fn check_for_debugger_visualizer<'tcx>(
                 _ => continue,
             };
 
-            let file = match (meta_item.name_or_empty(), meta_item.value_str()) {
-                (sym::natvis_file, Some(value)) => {
-                    match resolve_path(&tcx.sess.parse_sess, value.as_str(), attr.span) {
-                        Ok(file) => file,
-                        Err(mut err) => {
-                            err.emit();
-                            continue;
-                        }
-                    }
-                }
-                (_, _) => continue,
+            let visualizer_type = match meta_item.name_or_empty() {
+                sym::natvis_file => DebuggerVisualizerType::Natvis,
+                sym::gdb_script_file => DebuggerVisualizerType::GdbPrettyPrinter,
+                _ => continue,
             };
 
-            if file.is_file() {
-                let contents = match std::fs::read(&file) {
-                    Ok(contents) => contents,
-                    Err(err) => {
-                        tcx.sess
-                            .struct_span_err(
-                                attr.span,
-                                &format!(
-                                    "Unable to read contents of file `{}`. {}",
-                                    file.display(),
-                                    err
-                                ),
-                            )
-                            .emit();
-                        continue;
+            let file = match meta_item.value_str() {
+                Some(value) => {
+                    match resolve_path(&tcx.sess.parse_sess, value.as_str(), attr.span) {
+                        Ok(file) => file,
+                        _ => continue,
                     }
-                };
+                }
+                None => continue,
+            };
 
-                debugger_visualizers.insert(DebuggerVisualizerFile::new(
-                    Arc::from(contents),
-                    DebuggerVisualizerType::Natvis,
-                ));
-            } else {
-                tcx.sess
-                    .struct_span_err(attr.span, &format!("{} is not a valid file", file.display()))
-                    .emit();
+            match std::fs::read(&file) {
+                Ok(contents) => {
+                    debugger_visualizers
+                        .insert(DebuggerVisualizerFile::new(Arc::from(contents), visualizer_type));
+                }
+                _ => {}
             }
         }
     }