Eliminate the last three "did you mean" warning phrasings

Inspired by #15138 , this
eliminates the last three instances.

Also rephrase a comment that implied the use of "did you mean"
suggestions.

Author: joshtriplett

src/cargo/ops/cargo_compile/mod.rs

@@ -230,16 +230,17 @@ pub fn create_bcx<'a, 'gctx>(
     match build_config.intent {
         UserIntent::Test | UserIntent::Build | UserIntent::Check { .. } | UserIntent::Bench => {
             if ws.gctx().get_env("RUST_FLAGS").is_ok() {
-                gctx.shell().warn(
-                    "Cargo does not read `RUST_FLAGS` environment variable. Did you mean `RUSTFLAGS`?",
-                )?;
+                gctx.shell()
+                    .warn("ignoring environment variable `RUST_FLAGS`")?;
+                gctx.shell().note("rust flags are passed via `RUSTFLAGS`")?;
             }
         }
         UserIntent::Doc { .. } | UserIntent::Doctest => {
             if ws.gctx().get_env("RUSTDOC_FLAGS").is_ok() {
-                gctx.shell().warn(
-                    "Cargo does not read `RUSTDOC_FLAGS` environment variable. Did you mean `RUSTDOCFLAGS`?"
-                )?;
+                gctx.shell()
+                    .warn("ignoring environment variable `RUSTDOC_FLAGS`")?;
+                gctx.shell()
+                    .note("rustdoc flags are passed via `RUSTDOCFLAGS`")?;
             }
         }
     }

src/cargo/sources/registry/mod.rs

@@ -846,7 +846,7 @@ impl<'gctx> Source for RegistrySource<'gctx> {
                 // Attempt to handle misspellings by searching for a chain of related
                 // names to the original name. The resolver will later
                 // reject any candidates that have the wrong name, and with this it'll
-                // along the way produce helpful "did you mean?" suggestions.
+                // have enough information to offer "a similar crate exists" suggestions.
                 // For now we only try the canonical lysing `-` to `_` and vice versa.
                 // More advanced fuzzy searching become in the future.
                 for name_permutation in [

src/cargo/util/toml/mod.rs

@@ -1747,8 +1747,8 @@ pub fn to_real_manifest(
 
     if summary.features().contains_key("default-features") {
         warnings.push(
-            "`default-features = [\"..\"]` was found in [features]. \
-                 Did you mean to use `default = [\"..\"]`?"
+            "`[features]` defines a feature named `default-features`
+note: only a feature named `default` will be enabled by default"
                 .to_string(),
         )
     }

tests/testsuite/features.rs

@@ -1851,13 +1851,16 @@ fn warn_if_default_features() {
         .file("bar/src/lib.rs", "pub fn bar() {}")
         .build();
 
-    p.cargo("check").with_stderr_data(str![[r#"
-[WARNING] `default-features = [".."]` was found in [features]. Did you mean to use `default = [".."]`?
+    p.cargo("check")
+        .with_stderr_data(str![[r#"
+[WARNING] `[features]` defines a feature named `default-features`
+[NOTE] only a feature named `default` will be enabled by default
 [LOCKING] 1 package to latest compatible version
 [CHECKING] foo v0.0.1 ([ROOT]/foo)
 [FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
 
-"#]]).run();
+"#]])
+        .run();
 }
 
 #[cargo_test]

tests/testsuite/rustdocflags.rs

@@ -115,7 +115,8 @@ fn rustdocflags_misspelled() {
     p.cargo("doc")
         .env("RUSTDOC_FLAGS", "foo")
         .with_stderr_data(str![[r#"
-[WARNING] Cargo does not read `RUSTDOC_FLAGS` environment variable. Did you mean `RUSTDOCFLAGS`?
+[WARNING] ignoring environment variable `RUSTDOC_FLAGS`
+[NOTE] rustdoc flags are passed via `RUSTDOCFLAGS`
 ...
 "#]])
         .run();

tests/testsuite/rustflags.rs

@@ -1443,7 +1443,8 @@ fn env_rustflags_misspelled() {
             .env("RUST_FLAGS", "foo")
             .with_stderr_data(
                 "\
-[WARNING] Cargo does not read `RUST_FLAGS` environment variable. Did you mean `RUSTFLAGS`?
+[WARNING] ignoring environment variable `RUST_FLAGS`
+[NOTE] rust flags are passed via `RUSTFLAGS`
 ...
 ",
             )
@@ -1471,7 +1472,8 @@ fn env_rustflags_misspelled_build_script() {
     p.cargo("check")
         .env("RUST_FLAGS", "foo")
         .with_stderr_data(str![[r#"
-[WARNING] Cargo does not read `RUST_FLAGS` environment variable. Did you mean `RUSTFLAGS`?
+[WARNING] ignoring environment variable `RUST_FLAGS`
+[NOTE] rust flags are passed via `RUSTFLAGS`
 [COMPILING] foo v0.0.1 ([ROOT]/foo)
 [FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s