Auto merge of #10566 - Urgau:check-cfg-improvements, r=ehuss

Improve support of condition compilation checking

This PR is a series of improvements to the check-cfg implementation.

### What does this PR try to resolve?

This PR resolve the concern expressed in #10486 (comment) that is:
 * Fixing the tests on Windows: e8aa51d
 * Merging all the -Z flags under -Zcheck-cfg: 969e282
 * Moving of all of the check-cfg tests into a separate module: c18b442
 * And removing of an unused parameter: 068bdf4

### How should we test and review this PR?

This PR should be reviewed commit by commit and tested with the automated tests or examples.

### Additional information

I decided to use a custom macro to make the test functional under Windows, the macro generate a contains line with the correct escaping depending on the platform (windows or not windows).

src/cargo/core/compiler/context/mod.rs

@@ -224,7 +224,7 @@ impl<'a, 'cfg> Context<'a, 'cfg> {
                 let mut unstable_opts = false;
                 let mut args = compiler::extern_args(&self, unit, &mut unstable_opts)?;
                 args.extend(compiler::lto_args(&self, unit));
-                args.extend(compiler::features_args(&self, unit));
+                args.extend(compiler::features_args(unit));
                 args.extend(compiler::check_cfg_args(&self, unit));
 
                 let script_meta = self.find_build_script_metadata(unit);

src/cargo/core/compiler/mod.rs

@@ -645,7 +645,7 @@ fn rustdoc(cx: &mut Context<'_, '_>, unit: &Unit) -> CargoResult<Work> {
     paths::create_dir_all(&doc_dir)?;
 
     rustdoc.arg("-o").arg(&doc_dir);
-    rustdoc.args(&features_args(cx, unit));
+    rustdoc.args(&features_args(unit));
     rustdoc.args(&check_cfg_args(cx, unit));
 
     add_error_format_and_color(cx, &mut rustdoc);
@@ -966,7 +966,7 @@ fn build_base_args(
         cmd.arg("--cfg").arg("test");
     }
 
-    cmd.args(&features_args(cx, unit));
+    cmd.args(&features_args(unit));
     cmd.args(&check_cfg_args(cx, unit));
 
     let meta = cx.files().metadata(unit);
@@ -1042,7 +1042,7 @@ fn build_base_args(
 }
 
 /// All active features for the unit passed as --cfg
-fn features_args(_cx: &Context<'_, '_>, unit: &Unit) -> Vec<OsString> {
+fn features_args(unit: &Unit) -> Vec<OsString> {
     let mut args = Vec::with_capacity(unit.features.len() * 2);
 
     for feat in &unit.features {
@@ -1055,43 +1055,42 @@ fn features_args(_cx: &Context<'_, '_>, unit: &Unit) -> Vec<OsString> {
 
 /// Generate the --check-cfg arguments for the unit
 fn check_cfg_args(cx: &Context<'_, '_>, unit: &Unit) -> Vec<OsString> {
-    if !cx.bcx.config.cli_unstable().check_cfg_features
-        && !cx.bcx.config.cli_unstable().check_cfg_well_known_names
-        && !cx.bcx.config.cli_unstable().check_cfg_well_known_values
+    if let Some((features, well_known_names, well_known_values)) =
+        cx.bcx.config.cli_unstable().check_cfg
     {
-        return Vec::new();
-    }
-
-    let mut args = Vec::with_capacity(unit.pkg.summary().features().len() * 2 + 4);
-    args.push(OsString::from("-Zunstable-options"));
+        let mut args = Vec::with_capacity(unit.pkg.summary().features().len() * 2 + 4);
+        args.push(OsString::from("-Zunstable-options"));
+
+        if features {
+            // This generate something like this:
+            //  - values(feature)
+            //  - values(feature, "foo", "bar")
+            let mut arg = OsString::from("values(feature");
+            for (&feat, _) in unit.pkg.summary().features() {
+                arg.push(", \"");
+                arg.push(&feat);
+                arg.push("\"");
+            }
+            arg.push(")");
 
-    if cx.bcx.config.cli_unstable().check_cfg_features {
-        // This generate something like this:
-        //  - values(feature)
-        //  - values(feature, "foo", "bar")
-        let mut arg = OsString::from("values(feature");
-        for (&feat, _) in unit.pkg.summary().features() {
-            arg.push(", \"");
-            arg.push(&feat);
-            arg.push("\"");
+            args.push(OsString::from("--check-cfg"));
+            args.push(arg);
         }
-        arg.push(")");
 
-        args.push(OsString::from("--check-cfg"));
-        args.push(arg);
-    }
+        if well_known_names {
+            args.push(OsString::from("--check-cfg"));
+            args.push(OsString::from("names()"));
+        }
 
-    if cx.bcx.config.cli_unstable().check_cfg_well_known_names {
-        args.push(OsString::from("--check-cfg"));
-        args.push(OsString::from("names()"));
-    }
+        if well_known_values {
+            args.push(OsString::from("--check-cfg"));
+            args.push(OsString::from("values()"));
+        }
 
-    if cx.bcx.config.cli_unstable().check_cfg_well_known_values {
-        args.push(OsString::from("--check-cfg"));
-        args.push(OsString::from("values()"));
+        args
+    } else {
+        Vec::new()
     }
-
-    args
 }
 
 fn lto_args(cx: &Context<'_, '_>, unit: &Unit) -> Vec<OsString> {

src/cargo/core/features.rs

@@ -641,9 +641,7 @@ unstable_cli_options!(
     build_std_features: Option<Vec<String>>  = ("Configure features enabled for the standard library itself when building the standard library"),
     config_include: bool = ("Enable the `include` key in config files"),
     credential_process: bool = ("Add a config setting to fetch registry authentication tokens by calling an external process"),
-    check_cfg_features: bool = ("Enable compile-time checking of features in `cfg`"),
-    check_cfg_well_known_names: bool = ("Enable compile-time checking of well known names in `cfg`"),
-    check_cfg_well_known_values: bool = ("Enable compile-time checking of well known values in `cfg`"),
+    check_cfg: Option<(/*features:*/ bool, /*well_known_names:*/ bool, /*well_known_values:*/ bool)> = ("Specify scope of compile-time checking of `cfg` names/values"),
     doctest_in_workspace: bool = ("Compile doctests with paths relative to the workspace root"),
     doctest_xcompile: bool = ("Compile and run doctests for non-host target using runner config"),
     dual_proc_macros: bool = ("Build proc-macros for both the host and the target"),
@@ -785,6 +783,27 @@ impl CliUnstable {
             }
         }
 
+        fn parse_check_cfg(value: Option<&str>) -> CargoResult<Option<(bool, bool, bool)>> {
+            if let Some(value) = value {
+                let mut features = false;
+                let mut well_known_names = false;
+                let mut well_known_values = false;
+
+                for e in value.split(',') {
+                    match e {
+                        "features" => features = true,
+                        "names" => well_known_names = true,
+                        "values" => well_known_values = true,
+                        _ => bail!("flag -Zcheck-cfg only takes `features`, `names` or `values` as valid inputs"),
+                    }
+                }
+
+                Ok(Some((features, well_known_names, well_known_values)))
+            } else {
+                Ok(None)
+            }
+        }
+
         // Asserts that there is no argument to the flag.
         fn parse_empty(key: &str, value: Option<&str>) -> CargoResult<bool> {
             if let Some(v) = value {
@@ -842,9 +861,7 @@ impl CliUnstable {
             "minimal-versions" => self.minimal_versions = parse_empty(k, v)?,
             "advanced-env" => self.advanced_env = parse_empty(k, v)?,
             "config-include" => self.config_include = parse_empty(k, v)?,
-            "check-cfg-features" => self.check_cfg_features = parse_empty(k, v)?,
-            "check-cfg-well-known-names" => self.check_cfg_well_known_names = parse_empty(k, v)?,
-            "check-cfg-well-known-values" => self.check_cfg_well_known_values = parse_empty(k, v)?,
+            "check-cfg" => self.check_cfg = parse_check_cfg(v)?,
             "dual-proc-macros" => self.dual_proc_macros = parse_empty(k, v)?,
             // can also be set in .cargo/config or with and ENV
             "mtime-on-use" => self.mtime_on_use = parse_empty(k, v)?,

src/doc/src/reference/unstable.md

@@ -1188,44 +1188,27 @@ For instance:
 cargo doc -Z unstable-options -Z rustdoc-scrape-examples=examples
 ```
 
-### check-cfg-features
+### check-cfg
 
 * RFC: [#3013](https://github.com/rust-lang/rfcs/pull/3013)
+* Tracking Issue: [#10554](https://github.com/rust-lang/cargo/issues/10554)
 
-The `-Z check-cfg-features` argument tells Cargo to pass all possible features of a package to
-`rustc` and `rustdoc` unstable `--check-cfg` command line as `--check-cfg=values(feature, ...)`.
-This enables compile time checking of feature values in `#[cfg]`, `cfg!` and `#[cfg_attr]`.
-Note than this command line options will probably become the default when stabilizing.
-For instance:
-
-```
-cargo check -Z unstable-options -Z check-cfg-features
-```
-
-### check-cfg-well-known-names
-
-* RFC: [#3013](https://github.com/rust-lang/rfcs/pull/3013)
+`-Z check-cfg` command line enables compile time checking of name and values in `#[cfg]`, `cfg!`,
+`#[link]` and `#[cfg_attr]` with the `rustc` and `rustdoc` unstable `--check-cfg` command line.
 
-The `-Z check-cfg-well-known-names` argument tells Cargo to activate `rustc` and `rustdoc` unstable
-`--check-cfg` command line as `--check-cfg=names()`.
-This enables compile time checking of well known names in `#[cfg]`, `cfg!` and `#[cfg_attr]`.
-For instance:
-
-```
-cargo check -Z unstable-options -Z check-cfg-well-known-names
-```
-
-### check-cfg-well-known-values
-
-* RFC: [#3013](https://github.com/rust-lang/rfcs/pull/3013)
+It's values are:
+ - `features`: enables features checking via `--check-cfg=values(feature, ...)`.
+    Note than this command line options will probably become the default when stabilizing.
+ - `names`: enables well known names checking via `--check-cfg=names()`.
+ - `values`: enables well known values checking via `--check-cfg=values()`.
 
-The `-Z check-cfg-well-known-values` argument tells Cargo to activate `rustc` and `rustdoc` unstable
-`--check-cfg` command line as `--check-cfg=values()`.
-This enables compile time checking of well known values in `#[cfg]`, `cfg!` and `#[cfg_attr]`.
 For instance:
 
 ```
-cargo check -Z unstable-options -Z check-cfg-well-known-values
+cargo check -Z unstable-options -Z check-cfg=features
+cargo check -Z unstable-options -Z check-cfg=names
+cargo check -Z unstable-options -Z check-cfg=values
+cargo check -Z unstable-options -Z check-cfg=features,names,values
 ```
 
 ### workspace-inheritance