Disable most Cargo check-cfg help in external macros

Author: Urgau

compiler/rustc_lint/src/context/diagnostics/check_cfg.rs

@@ -85,6 +85,7 @@ pub(super) fn unexpected_cfg_name(
     };
 
     let is_from_cargo = rustc_session::utils::was_invoked_from_cargo();
+    let is_from_external_macro = rustc_middle::lint::in_external_macro(sess, name_span);
     let mut is_feature_cfg = name == sym::feature;
 
     let code_sugg = if is_feature_cfg && is_from_cargo {
@@ -185,7 +186,11 @@ pub(super) fn unexpected_cfg_name(
     };
 
     let invocation_help = if is_from_cargo {
-        let sub = if !is_feature_cfg { Some(cargo_help_sub(sess, &inst)) } else { None };
+        let sub = if !is_feature_cfg && !is_from_external_macro {
+            Some(cargo_help_sub(sess, &inst))
+        } else {
+            None
+        };
         lints::unexpected_cfg_name::InvocationHelp::Cargo { sub }
     } else {
         lints::unexpected_cfg_name::InvocationHelp::Rustc(lints::UnexpectedCfgRustcHelp::new(
@@ -216,7 +221,9 @@ pub(super) fn unexpected_cfg_value(
         .copied()
         .flatten()
         .collect();
+
     let is_from_cargo = rustc_session::utils::was_invoked_from_cargo();
+    let is_from_external_macro = rustc_middle::lint::in_external_macro(sess, name_span);
 
     // Show the full list if all possible values for a given name, but don't do it
     // for names as the possibilities could be very long
@@ -284,13 +291,13 @@ pub(super) fn unexpected_cfg_value(
     };
 
     let invocation_help = if is_from_cargo {
-        let help = if name == sym::feature {
+        let help = if name == sym::feature && !is_from_external_macro {
             if let Some((value, _value_span)) = value {
                 Some(lints::unexpected_cfg_value::CargoHelp::AddFeature { value })
             } else {
                 Some(lints::unexpected_cfg_value::CargoHelp::DefineFeatures)
             }
-        } else if can_suggest_adding_value {
+        } else if can_suggest_adding_value && !is_from_external_macro {
             Some(lints::unexpected_cfg_value::CargoHelp::Other(cargo_help_sub(sess, &inst)))
         } else {
             None

tests/ui/check-cfg/report-in-external-macros.cargo.stderr

@@ -5,11 +5,6 @@ LL |     cfg_macro::my_lib_macro!();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: expected names are: `clippy`, `debug_assertions`, `doc`, `doctest`, `feature`, `fmt_debug`, `miri`, `overflow_checks`, `panic`, `proc_macro`, `relocation_model`, `rustfmt`, `sanitize`, `sanitizer_cfi_generalize_pointers`, `sanitizer_cfi_normalize_integers`, `target_abi`, `target_arch`, `target_endian`, `target_env`, `target_family`, `target_feature`, `target_has_atomic`, `target_has_atomic_equal_alignment`, `target_has_atomic_load_store`, `target_os`, `target_pointer_width`, `target_thread_local`, `target_vendor`, `test`, `ub_checks`, `unix`, and `windows`
-   = help: consider using a Cargo feature instead
-   = help: or consider adding in `Cargo.toml` the `check-cfg` lint config for the lint:
-            [lints.rust]
-            unexpected_cfgs = { level = "warn", check-cfg = ['cfg(my_lib_cfg)'] }
-   = help: or consider adding `println!("cargo::rustc-check-cfg=cfg(my_lib_cfg)");` to the top of the `build.rs`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration
    = note: `#[warn(unexpected_cfgs)]` on by default
    = note: this warning originates in the macro `cfg_macro::my_lib_macro` (in Nightly builds, run with -Z macro-backtrace for more info)
@@ -31,7 +26,6 @@ LL |     cfg_macro::my_lib_macro_feature!();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: no expected values for `feature`
-   = help: consider adding `UNEXPECTED_FEATURE` as a feature in `Cargo.toml`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration
    = note: this warning originates in the macro `cfg_macro::my_lib_macro_feature` (in Nightly builds, run with -Z macro-backtrace for more info)