don't repeat metadata section key

Author: romnn

src/lib.rs

@@ -29,16 +29,29 @@ pub use runner::{
 };
 pub use workspace::Workspace;
 
-use crate::cfg_eval::RustcCfgEvaluator;
-use crate::cli::cargo_subcommand;
-use crate::runner::print_feature_combination_error;
-use crate::target::{RustcTargetDetector, TargetDetector};
+use cfg_eval::RustcCfgEvaluator;
+use cli::cargo_subcommand;
+use runner::print_feature_combination_error;
+use target::{RustcTargetDetector, TargetDetector};
 
 use color_eyre::eyre;
 use std::process;
 
+/// Expands to the metadata key literal `"cargo-feature-combinations"`.
+macro_rules! metadata_key {
+    () => {
+        "cargo-feature-combinations"
+    };
+}
+
 /// Key used to look up this tool's configuration in Cargo metadata.
-pub(crate) const METADATA_KEY: &str = "cargo-feature-combinations";
+pub(crate) const METADATA_KEY: &str = metadata_key!();
+
+/// TOML section header for per-package configuration.
+pub(crate) const PKG_METADATA_SECTION: &str = concat!("[package.metadata.", metadata_key!(), "]");
+
+/// TOML section header for workspace-level configuration.
+pub(crate) const WS_METADATA_SECTION: &str = concat!("[workspace.metadata.", metadata_key!(), "]");
 
 /// Run the cargo subcommand for all relevant feature combinations.
 ///

src/package.rs

@@ -1,7 +1,7 @@
 //! Package-level configuration, feature combination generation, and error types.
 
-use crate::METADATA_KEY;
 use crate::config::Config;
+use crate::{METADATA_KEY, PKG_METADATA_SECTION};
 use color_eyre::eyre;
 use itertools::Itertools;
 use std::collections::{BTreeMap, BTreeSet, HashSet};
@@ -37,13 +37,10 @@ impl fmt::Display for FeatureCombinationError {
             } => {
                 write!(
                     f,
-                    "too many configurations for package `{}`: {} feature(s) would produce {} combinations (limit: {})",
-                    package,
-                    num_features,
+                    "too many configurations for package `{package}`: {num_features} feature(s) would produce {} combinations (limit: {limit})",
                     num_configurations
                         .map(|v| v.to_string())
                         .unwrap_or_else(|| "an unbounded number of".to_string()),
-                    limit
                 )
             }
         }
@@ -93,21 +90,21 @@ impl Package for cargo_metadata::Package {
 
         if !config.deprecated.skip_feature_sets.is_empty() {
             eprintln!(
-                "warning: [package.metadata.cargo-feature-combinations].skip_feature_sets in package `{}` is deprecated; use exclude_feature_sets instead",
+                "warning: {PKG_METADATA_SECTION}.skip_feature_sets in package `{}` is deprecated; use exclude_feature_sets instead",
                 self.name,
             );
         }
 
         if !config.deprecated.denylist.is_empty() {
             eprintln!(
-                "warning: [package.metadata.cargo-feature-combinations].denylist in package `{}` is deprecated; use exclude_features instead",
+                "warning: {PKG_METADATA_SECTION}.denylist in package `{}` is deprecated; use exclude_features instead",
                 self.name,
             );
         }
 
         if !config.deprecated.exact_combinations.is_empty() {
             eprintln!(
-                "warning: [package.metadata.cargo-feature-combinations].exact_combinations in package `{}` is deprecated; use include_feature_sets instead",
+                "warning: {PKG_METADATA_SECTION}.exact_combinations in package `{}` is deprecated; use include_feature_sets instead",
                 self.name,
             );
         }

src/runner.rs

@@ -1,5 +1,6 @@
 //! Cargo command execution, output parsing, summary printing, and matrix output.
 
+use crate::PKG_METADATA_SECTION;
 use crate::cfg_eval::RustcCfgEvaluator;
 use crate::cli::{CargoSubcommand, Options, cargo_subcommand};
 use crate::package::{FeatureCombinationError, Package};
@@ -133,7 +134,7 @@ pub(crate) fn print_feature_combination_error(err: &FeatureCombinationError) {
             let _ = stderr.reset();
             let _ = writeln!(
                 &mut stderr,
-                "    Consider restricting the matrix using [package.metadata.cargo-feature-combinations].only_features"
+                "    Consider restricting the matrix using {PKG_METADATA_SECTION}.only_features",
             );
             let _ = writeln!(
                 &mut stderr,

src/workspace.rs

@@ -1,8 +1,8 @@
 //! Workspace-level configuration and package discovery.
 
-use crate::METADATA_KEY;
 use crate::config::{Config, WorkspaceConfig};
 use crate::package::Package;
+use crate::{METADATA_KEY, PKG_METADATA_SECTION, WS_METADATA_SECTION};
 use color_eyre::eyre;
 
 /// Abstraction over a Cargo workspace used by this crate.
@@ -47,7 +47,7 @@ impl Workspace for cargo_metadata::Metadata {
 
             if !config.exclude_packages.is_empty() {
                 eprintln!(
-                    "warning: [package.metadata.cargo-feature-combinations].exclude_packages in the workspace root package is deprecated; use [workspace.metadata.cargo-feature-combinations].exclude_packages instead",
+                    "warning: {PKG_METADATA_SECTION}.exclude_packages in the workspace root package is deprecated; use {WS_METADATA_SECTION}.exclude_packages instead",
                 );
             }
 
@@ -69,7 +69,7 @@ impl Workspace for cargo_metadata::Metadata {
                     && !config.exclude_packages.is_empty()
                 {
                     eprintln!(
-                        "warning: [package.metadata.cargo-feature-combinations].exclude_packages in package `{}` has no effect; this field is only read from the workspace root Cargo.toml",
+                        "warning: {PKG_METADATA_SECTION}.exclude_packages in package `{}` has no effect; this field is only read from the workspace root Cargo.toml",
                         package.name,
                     );
                 }
@@ -89,7 +89,7 @@ impl Workspace for cargo_metadata::Metadata {
 
                     if has_values {
                         eprintln!(
-                            "warning: [workspace.metadata.cargo-feature-combinations].exclude_packages in package `{}` has no effect; workspace metadata is only read from the workspace root Cargo.toml",
+                            "warning: {WS_METADATA_SECTION}.exclude_packages in package `{}` has no effect; workspace metadata is only read from the workspace root Cargo.toml",
                             package.name,
                         );
                     }