Do not suggest using -Zmacro-backtrace for builtin macros

For macros that are implemented on the compiler, or that are annotated with `rustc_diagnostic_item`, which have arbitrary implementations from the point of view of the user and might as well be intrinsics, we do *not* mention the `-Zmacro-backtrace` flag. This includes `derive`s and standard macros like `panic!` and `format!`.

Author: estebank

compiler/rustc_errors/src/emitter.rs

@@ -297,7 +297,9 @@ pub trait Emitter: Translate {
                     // are some which do actually involve macros.
                     ExpnKind::Desugaring(..) | ExpnKind::AstPass(..) => None,
 
-                    ExpnKind::Macro(macro_kind, name) => Some((macro_kind, name)),
+                    ExpnKind::Macro(macro_kind, name) => {
+                        Some((macro_kind, name, expn_data.builtin_macro))
+                    }
                 }
             })
             .collect();
@@ -309,13 +311,18 @@ pub trait Emitter: Translate {
         self.render_multispans_macro_backtrace(span, children, backtrace);
 
         if !backtrace {
-            if let Some((macro_kind, name)) = has_macro_spans.first() {
+            // Skip builtin macros, as their expansion isn't relevant to the end user. This includes
+            // actual intrinsics, like `asm!`, as well as macros by example, like `println!`, which
+            // might as well be an intrinsic as far as the user is concerned.
+            if let Some((macro_kind, name, _)) = has_macro_spans.first()
+                && let Some((_, _, false)) = has_macro_spans.last()
+            {
                 // Mark the actual macro this originates from
-                let and_then = if let Some((macro_kind, last_name)) = has_macro_spans.last()
+                let and_then = if let Some((macro_kind, last_name, _)) = has_macro_spans.last()
                     && last_name != name
                 {
                     let descr = macro_kind.descr();
-                    format!(" which comes from the expansion of the {descr} `{last_name}`",)
+                    format!(" which comes from the expansion of the {descr} `{last_name}`")
                 } else {
                     "".to_string()
                 };

compiler/rustc_expand/src/base.rs

@@ -757,6 +757,11 @@ pub struct SyntaxExtension {
     /// Built-in macros have a couple of special properties like availability
     /// in `#[no_implicit_prelude]` modules, so we have to keep this flag.
     pub builtin_name: Option<Symbol>,
+    /// Whether this macro is either a compiler intrinsic (implied by the above field) or a macro
+    /// provided by the standard library where the specific of its implementation are not relevant
+    /// to the end user, like for `format!` or `println!`, which are normal macros by example, but
+    /// that is an implementation detail.
+    pub builtin: bool,
     /// Suppresses the `unsafe_code` lint for code produced by this macro.
     pub allow_internal_unsafe: bool,
     /// Enables the macro helper hack (`ident!(...)` -> `$crate::ident!(...)`) for this macro.
@@ -792,6 +797,7 @@ impl SyntaxExtension {
             helper_attrs: Vec::new(),
             edition,
             builtin_name: None,
+            builtin: false,
             kind,
             allow_internal_unsafe: false,
             local_inner_macros: false,
@@ -888,17 +894,19 @@ impl SyntaxExtension {
                 )
             })
             .unwrap_or_else(|| (None, helper_attrs));
+        let builtin = builtin_name.is_some()
+            || ast::attr::find_by_name(attrs, sym::rustc_diagnostic_item).is_some();
 
-        let stability = find_attr!(attrs, AttributeKind::Stability{stability, ..} => *stability);
+        let stability = find_attr!(attrs, AttributeKind::Stability { stability, .. } => *stability);
 
         // FIXME(jdonszelmann): make it impossible to miss the or_else in the typesystem
-        if let Some(sp) = find_attr!(attrs, AttributeKind::ConstStability{span, ..} => *span) {
+        if let Some(sp) = find_attr!(attrs, AttributeKind::ConstStability { span, .. } => *span) {
             sess.dcx().emit_err(errors::MacroConstStability {
                 span: sp,
                 head_span: sess.source_map().guess_head_span(span),
             });
         }
-        if let Some(sp) = find_attr!(attrs, AttributeKind::BodyStability{span, ..} => *span) {
+        if let Some(sp) = find_attr!(attrs, AttributeKind::BodyStability{ span, .. } => *span) {
             sess.dcx().emit_err(errors::MacroBodyStability {
                 span: sp,
                 head_span: sess.source_map().guess_head_span(span),
@@ -912,10 +920,14 @@ impl SyntaxExtension {
                 // FIXME(jdonszelmann): avoid the into_iter/collect?
                 .then(|| allow_internal_unstable.iter().map(|i| i.0).collect::<Vec<_>>().into()),
             stability,
-            deprecation: find_attr!(attrs, AttributeKind::Deprecation{deprecation, ..} => *deprecation),
+            deprecation: find_attr!(
+                attrs,
+                AttributeKind::Deprecation { deprecation, .. } => *deprecation
+            ),
             helper_attrs,
             edition,
             builtin_name,
+            builtin,
             allow_internal_unsafe,
             local_inner_macros,
             collapse_debuginfo,
@@ -1000,6 +1012,7 @@ impl SyntaxExtension {
             self.allow_internal_unsafe,
             self.local_inner_macros,
             self.collapse_debuginfo,
+            self.builtin,
         )
     }
 }

compiler/rustc_span/src/hygiene.rs

@@ -982,6 +982,11 @@ pub struct ExpnData {
     /// Should debuginfo for the macro be collapsed to the outermost expansion site (in other
     /// words, was the macro definition annotated with `#[collapse_debuginfo]`)?
     pub(crate) collapse_debuginfo: bool,
+    /// Whether this macro expansion came from a compiler implemented macro (`rustc_builtin_macro`)
+    /// or a macro by example provided by the standard library (marked with
+    /// `rustc_diagnostic_item`). If this is true, then we do not display the standard note telling
+    /// people to use the `-Zmacro-backtrace` flag.
+    pub builtin_macro: bool,
 }
 
 impl !PartialEq for ExpnData {}
@@ -1000,6 +1005,7 @@ impl ExpnData {
         allow_internal_unsafe: bool,
         local_inner_macros: bool,
         collapse_debuginfo: bool,
+        builtin_macro: bool,
     ) -> ExpnData {
         ExpnData {
             kind,
@@ -1014,6 +1020,7 @@ impl ExpnData {
             allow_internal_unsafe,
             local_inner_macros,
             collapse_debuginfo,
+            builtin_macro,
         }
     }
 
@@ -1038,6 +1045,7 @@ impl ExpnData {
             allow_internal_unsafe: false,
             local_inner_macros: false,
             collapse_debuginfo: false,
+            builtin_macro: false,
         }
     }
 

compiler/rustc_span/src/symbol.rs

@@ -1503,6 +1503,7 @@ symbols! {
         panic_implementation,
         panic_in_cleanup,
         panic_info,
+        panic_internals,
         panic_location,
         panic_misaligned_pointer_dereference,
         panic_nounwind,

tests/run-make/non-unicode-env/non_unicode_env.stderr

@@ -3,16 +3,12 @@ error: environment variable `NON_UNICODE_VAR` is not a valid Unicode string
   |
 2 |     let _ = env!("NON_UNICODE_VAR");
   |             ^^^^^^^^^^^^^^^^^^^^^^^
-  |
-  = note: this error originates in the macro `env` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: environment variable `NON_UNICODE_VAR` is not a valid Unicode string
  --> non_unicode_env.rs:3:13
   |
 3 |     let _ = option_env!("NON_UNICODE_VAR");
   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-  |
-  = note: this error originates in the macro `option_env` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to 2 previous errors
 

tests/rustdoc-ui/doctest/relative-path-include-bytes-132203.edition2015.stdout

@@ -10,8 +10,6 @@ error: couldn't read `$DIR/relative-dir-empty-file`: $FILE_NOT_FOUND_MSG (os err
    |
 LL | let x = include_bytes!("relative-dir-empty-file");
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: this error originates in the macro `include_bytes` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to 1 previous error
 

tests/ui/alloc-error/alloc-error-handler-bad-signature-1.stderr

@@ -18,7 +18,6 @@ LL | fn oom(
    |    ^^^
 LL |     info: &Layout,
    |     -------------
-   = note: this error originates in the attribute macro `alloc_error_handler` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0308]: mismatched types
   --> $DIR/alloc-error-handler-bad-signature-1.rs:10:1
@@ -35,7 +34,6 @@ LL | |  }
    |
    = note:   expected type `!`
            found unit type `()`
-   = note: this error originates in the attribute macro `alloc_error_handler` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to 2 previous errors
 

tests/ui/alloc-error/alloc-error-handler-bad-signature-2.stderr

@@ -26,7 +26,6 @@ LL | fn oom(
    |    ^^^
 LL |     info: Layout,
    |     ------------
-   = note: this error originates in the attribute macro `alloc_error_handler` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0308]: mismatched types
   --> $DIR/alloc-error-handler-bad-signature-2.rs:10:1
@@ -43,7 +42,6 @@ LL | |  }
    |
    = note:   expected type `!`
            found unit type `()`
-   = note: this error originates in the attribute macro `alloc_error_handler` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to 2 previous errors
 

tests/ui/alloc-error/alloc-error-handler-bad-signature-3.stderr

@@ -14,7 +14,6 @@ note: function defined here
    |
 LL | fn oom() -> ! {
    |    ^^^
-   = note: this error originates in the attribute macro `alloc_error_handler` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to 1 previous error
 

tests/ui/allocator/not-an-allocator.stderr

@@ -7,7 +7,6 @@ LL | static A: usize = 0;
    |           ^^^^^ the trait `GlobalAlloc` is not implemented for `usize`
    |
    = help: the trait `GlobalAlloc` is implemented for `System`
-   = note: this error originates in the attribute macro `global_allocator` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied
   --> $DIR/not-an-allocator.rs:2:11
@@ -19,7 +18,6 @@ LL | static A: usize = 0;
    |
    = help: the trait `GlobalAlloc` is implemented for `System`
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-   = note: this error originates in the attribute macro `global_allocator` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied
   --> $DIR/not-an-allocator.rs:2:11
@@ -31,7 +29,6 @@ LL | static A: usize = 0;
    |
    = help: the trait `GlobalAlloc` is implemented for `System`
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-   = note: this error originates in the attribute macro `global_allocator` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied
   --> $DIR/not-an-allocator.rs:2:11
@@ -43,7 +40,6 @@ LL | static A: usize = 0;
    |
    = help: the trait `GlobalAlloc` is implemented for `System`
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-   = note: this error originates in the attribute macro `global_allocator` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to 4 previous errors