Auto merge of #125463 - GuillaumeGomez:rollup-287wx4y, r=GuillaumeGomez

Rollup of 6 pull requests

Successful merges:

 - #125263 (rust-lld: fallback to rustc's sysroot if there's no path to the linker in the target sysroot)
 - #125345 (rustc_codegen_llvm: add support for writing summary bitcode)
 - #125362 (Actually use TAIT instead of emulating it)
 - #125412 (Don't suggest adding the unexpected cfgs to the build-script it-self)
 - #125445 (Migrate `run-make/rustdoc-with-short-out-dir-option` to `rmake.rs`)
 - #125452 (Cleanup check-cfg handling in core and std)

r? `@ghost`
`@rustbot` modify labels: rollup

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

@@ -42,6 +42,22 @@ fn to_check_cfg_arg(name: Symbol, value: Option<Symbol>, quotes: EscapeQuotes) -
     }
 }
 
+fn cargo_help_sub(
+    sess: &Session,
+    inst: &impl Fn(EscapeQuotes) -> String,
+) -> lints::UnexpectedCfgCargoHelp {
+    // We don't want to suggest the `build.rs` way to expected cfgs if we are already in a
+    // `build.rs`. We therefor do a best effort check (looking if the `--crate-name` is
+    // `build_script_build`) to try to figure out if we are building a Cargo build script
+
+    let unescaped = &inst(EscapeQuotes::No);
+    if matches!(&sess.opts.crate_name, Some(crate_name) if crate_name == "build_script_build") {
+        lints::UnexpectedCfgCargoHelp::lint_cfg(unescaped)
+    } else {
+        lints::UnexpectedCfgCargoHelp::lint_cfg_and_build_rs(unescaped, &inst(EscapeQuotes::Yes))
+    }
+}
+
 pub(super) fn unexpected_cfg_name(
     sess: &Session,
     (name, name_span): (Symbol, Span),
@@ -162,14 +178,7 @@ pub(super) fn unexpected_cfg_name(
     let inst = |escape_quotes| to_check_cfg_arg(name, value.map(|(v, _s)| v), escape_quotes);
 
     let invocation_help = if is_from_cargo {
-        let sub = if !is_feature_cfg {
-            Some(lints::UnexpectedCfgCargoHelp::new(
-                &inst(EscapeQuotes::No),
-                &inst(EscapeQuotes::Yes),
-            ))
-        } else {
-            None
-        };
+        let sub = if !is_feature_cfg { 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(
@@ -267,10 +276,7 @@ pub(super) fn unexpected_cfg_value(
                 Some(lints::unexpected_cfg_value::CargoHelp::DefineFeatures)
             }
         } else if !is_cfg_a_well_know_name {
-            Some(lints::unexpected_cfg_value::CargoHelp::Other(lints::UnexpectedCfgCargoHelp::new(
-                &inst(EscapeQuotes::No),
-                &inst(EscapeQuotes::Yes),
-            )))
+            Some(lints::unexpected_cfg_value::CargoHelp::Other(cargo_help_sub(sess, &inst)))
         } else {
             None
         };

compiler/rustc_lint/src/lints.rs

@@ -1962,21 +1962,33 @@ pub struct UnitBindingsDiag {
 pub struct BuiltinNamedAsmLabel;
 
 #[derive(Subdiagnostic)]
-#[help(lint_unexpected_cfg_add_cargo_feature)]
-#[help(lint_unexpected_cfg_add_cargo_toml_lint_cfg)]
-#[help(lint_unexpected_cfg_add_build_rs_println)]
-pub struct UnexpectedCfgCargoHelp {
-    pub build_rs_println: String,
-    pub cargo_toml_lint_cfg: String,
+pub enum UnexpectedCfgCargoHelp {
+    #[help(lint_unexpected_cfg_add_cargo_feature)]
+    #[help(lint_unexpected_cfg_add_cargo_toml_lint_cfg)]
+    LintCfg { cargo_toml_lint_cfg: String },
+    #[help(lint_unexpected_cfg_add_cargo_feature)]
+    #[help(lint_unexpected_cfg_add_cargo_toml_lint_cfg)]
+    #[help(lint_unexpected_cfg_add_build_rs_println)]
+    LintCfgAndBuildRs { cargo_toml_lint_cfg: String, build_rs_println: String },
 }
 
 impl UnexpectedCfgCargoHelp {
-    pub fn new(unescaped: &str, escaped: &str) -> Self {
-        Self {
-            cargo_toml_lint_cfg: format!(
-                "\n [lints.rust]\n unexpected_cfgs = {{ level = \"warn\", check-cfg = ['{unescaped}'] }}",
-            ),
-            build_rs_println: format!("println!(\"cargo::rustc-check-cfg={escaped}\");",),
+    fn cargo_toml_lint_cfg(unescaped: &str) -> String {
+        format!(
+            "\n [lints.rust]\n unexpected_cfgs = {{ level = \"warn\", check-cfg = ['{unescaped}'] }}"
+        )
+    }
+
+    pub fn lint_cfg(unescaped: &str) -> Self {
+        UnexpectedCfgCargoHelp::LintCfg {
+            cargo_toml_lint_cfg: Self::cargo_toml_lint_cfg(unescaped),
+        }
+    }
+
+    pub fn lint_cfg_and_build_rs(unescaped: &str, escaped: &str) -> Self {
+        UnexpectedCfgCargoHelp::LintCfgAndBuildRs {
+            cargo_toml_lint_cfg: Self::cargo_toml_lint_cfg(unescaped),
+            build_rs_println: format!("println!(\"cargo::rustc-check-cfg={escaped}\");"),
         }
     }
 }