Merge #9227

9227: Add a config setting to disable the 'test' cfg in specified crates r=matklad a=lf-

If you are opening libcore from rust-lang/rust as opposed to e.g.
goto definition from some other crate which would use the sysroot
instance of libcore, a `#![cfg(not(test))]` would previously have made
all the code excluded from the module tree, breaking the editor
experience.

Core does not need to ever be edited with `#[cfg(test)]` enabled,
as the tests are in another crate.

This PR puts in a slight hack that checks for the crate name "core" and
turns off `#[cfg(test)]` for that crate.

Fixes #9203 
Fixes #9226 

Co-authored-by: Jade <[email protected]>

5 files changed, 115 insertions, 49 deletions

diff --git a/crates/cfg/src/lib.rs b/crates/cfg/src/lib.rs
index 03b8dd767..916d39a0b 100644
--- a/crates/cfg/src/lib.rs
+++ b/crates/cfg/src/lib.rs
@@ -1,4 +1,4 @@
-//! cfg defines conditional compiling options, `cfg` attibute parser and evaluator
+//! cfg defines conditional compiling options, `cfg` attribute parser and evaluator
 
 mod cfg_expr;
 mod dnf;
@@ -52,6 +52,7 @@ impl CfgOptions {
     }
 }
 
+#[derive(Clone, Debug, PartialEq, Eq)]
 pub struct CfgDiff {
     // Invariants: No duplicates, no atom that's both in `enable` and `disable`.
     enable: Vec<CfgAtom>,
@@ -59,6 +60,20 @@ pub struct CfgDiff {
 }
 
 impl CfgDiff {
+    /// Create a new CfgDiff. Will return None if the same item appears more than once in the set
+    /// of both.
+    pub fn new(enable: Vec<CfgAtom>, disable: Vec<CfgAtom>) -> Option<CfgDiff> {
+        let mut occupied = FxHashSet::default();
+        for item in enable.iter().chain(disable.iter()) {
+            if !occupied.insert(item) {
+                // was present
+                return None;
+            }
+        }
+
+        Some(CfgDiff { enable, disable })
+    }
+
     /// Returns the total number of atoms changed by this diff.
     pub fn len(&self) -> usize {
         self.enable.len() + self.disable.len()
diff --git a/crates/project_model/src/cargo_workspace.rs b/crates/project_model/src/cargo_workspace.rs
index ac079f83e..0935ea967 100644
--- a/crates/project_model/src/cargo_workspace.rs
+++ b/crates/project_model/src/cargo_workspace.rs
@@ -1,5 +1,6 @@
 //! See [`CargoWorkspace`].
 
+use std::iter;
 use std::path::PathBuf;
 use std::{convert::TryInto, ops, process::Command, sync::Arc};
 
@@ -12,6 +13,7 @@ use rustc_hash::FxHashMap;
 use serde::Deserialize;
 use serde_json::from_value;
 
+use crate::CfgOverrides;
 use crate::{build_data::BuildDataConfig, utf8_stdout};
 
 /// [`CargoWorkspace`] represents the logical structure of, well, a Cargo
@@ -76,6 +78,21 @@ pub struct CargoConfig {
 
     /// rustc private crate source
     pub rustc_source: Option<RustcSource>,
+
+    /// crates to disable `#[cfg(test)]` on
+    pub unset_test_crates: Vec<String>,
+}
+
+impl CargoConfig {
+    pub fn cfg_overrides(&self) -> CfgOverrides {
+        self.unset_test_crates
+            .iter()
+            .cloned()
+            .zip(iter::repeat_with(|| {
+                cfg::CfgDiff::new(Vec::new(), vec![cfg::CfgAtom::Flag("test".into())]).unwrap()
+            }))
+            .collect()
+    }
 }
 
 pub type Package = Idx<PackageData>;
diff --git a/crates/project_model/src/lib.rs b/crates/project_model/src/lib.rs
index 8c6cf94c2..1d408dff2 100644
--- a/crates/project_model/src/lib.rs
+++ b/crates/project_model/src/lib.rs
@@ -41,7 +41,7 @@ pub use crate::{
     },
     project_json::{ProjectJson, ProjectJsonData},
     sysroot::Sysroot,
-    workspace::{PackageRoot, ProjectWorkspace},
+    workspace::{CfgOverrides, PackageRoot, ProjectWorkspace},
 };
 
 pub use proc_macro_api::ProcMacroClient;
diff --git a/crates/project_model/src/workspace.rs b/crates/project_model/src/workspace.rs
index ef0f3c9e4..d8217f714 100644
--- a/crates/project_model/src/workspace.rs
+++ b/crates/project_model/src/workspace.rs
@@ -7,7 +7,7 @@ use std::{collections::VecDeque, fmt, fs, path::Path, process::Command};
 use anyhow::{format_err, Context, Result};
 use base_db::{CrateDisplayName, CrateGraph, CrateId, CrateName, Edition, Env, FileId, ProcMacro};
 use cargo_workspace::DepKind;
-use cfg::CfgOptions;
+use cfg::{CfgDiff, CfgOptions};
 use paths::{AbsPath, AbsPathBuf};
 use proc_macro_api::ProcMacroClient;
 use rustc_hash::{FxHashMap, FxHashSet};
@@ -22,6 +22,8 @@ use crate::{
     Sysroot, TargetKind,
 };
 
+pub type CfgOverrides = FxHashMap<String, CfgDiff>;
+
 /// `PackageRoot` describes a package root folder.
 /// Which may be an external dependency, or a member of
 /// the current workspace.
@@ -46,6 +48,7 @@ pub enum ProjectWorkspace {
         /// FIXME: make this a per-crate map, as, eg, build.rs might have a
         /// different target.
         rustc_cfg: Vec<CfgFlag>,
+        cfg_overrides: CfgOverrides,
     },
     /// Project workspace was manually specified using a `rust-project.json` file.
     Json { project: ProjectJson, sysroot: Option<Sysroot>, rustc_cfg: Vec<CfgFlag> },
@@ -67,7 +70,7 @@ impl fmt::Debug for ProjectWorkspace {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         // Make sure this isn't too verbose.
         match self {
-            ProjectWorkspace::Cargo { cargo, sysroot, rustc, rustc_cfg } => f
+            ProjectWorkspace::Cargo { cargo, sysroot, rustc, rustc_cfg, cfg_overrides } => f
                 .debug_struct("Cargo")
                 .field("root", &cargo.workspace_root().file_name())
                 .field("n_packages", &cargo.packages().len())
@@ -77,6 +80,7 @@ impl fmt::Debug for ProjectWorkspace {
                     &rustc.as_ref().map_or(0, |rc| rc.packages().len()),
                 )
                 .field("n_rustc_cfg", &rustc_cfg.len())
+                .field("n_cfg_overrides", &cfg_overrides.len())
                 .finish(),
             ProjectWorkspace::Json { project, sysroot, rustc_cfg } => {
                 let mut debug_struct = f.debug_struct("Json");
@@ -164,7 +168,9 @@ impl ProjectWorkspace {
                 };
 
                 let rustc_cfg = rustc_cfg::get(Some(&cargo_toml), config.target.as_deref());
-                ProjectWorkspace::Cargo { cargo, sysroot, rustc, rustc_cfg }
+
+                let cfg_overrides = config.cfg_overrides();
+                ProjectWorkspace::Cargo { cargo, sysroot, rustc, rustc_cfg, cfg_overrides }
             }
         };
 
@@ -213,43 +219,45 @@ impl ProjectWorkspace {
                     })
                 }))
                 .collect::<Vec<_>>(),
-            ProjectWorkspace::Cargo { cargo, sysroot, rustc, rustc_cfg: _ } => cargo
-                .packages()
-                .map(|pkg| {
-                    let is_member = cargo[pkg].is_member;
-                    let pkg_root = cargo[pkg].root().to_path_buf();
-
-                    let mut include = vec![pkg_root.clone()];
-                    include.extend(
-                        build_data
-                            .and_then(|it| it.get(cargo.workspace_root()))
-                            .and_then(|map| map.get(&cargo[pkg].id))
-                            .and_then(|it| it.out_dir.clone()),
-                    );
+            ProjectWorkspace::Cargo { cargo, sysroot, rustc, rustc_cfg: _, cfg_overrides: _ } => {
+                cargo
+                    .packages()
+                    .map(|pkg| {
+                        let is_member = cargo[pkg].is_member;
+                        let pkg_root = cargo[pkg].root().to_path_buf();
+
+                        let mut include = vec![pkg_root.clone()];
+                        include.extend(
+                            build_data
+                                .and_then(|it| it.get(cargo.workspace_root()))
+                                .and_then(|map| map.get(&cargo[pkg].id))
+                                .and_then(|it| it.out_dir.clone()),
+                        );
 
-                    let mut exclude = vec![pkg_root.join(".git")];
-                    if is_member {
-                        exclude.push(pkg_root.join("target"));
-                    } else {
-                        exclude.push(pkg_root.join("tests"));
-                        exclude.push(pkg_root.join("examples"));
-                        exclude.push(pkg_root.join("benches"));
-                    }
-                    PackageRoot { is_member, include, exclude }
-                })
-                .chain(sysroot.crates().map(|krate| PackageRoot {
-                    is_member: false,
-                    include: vec![sysroot[krate].root_dir().to_path_buf()],
-                    exclude: Vec::new(),
-                }))
-                .chain(rustc.into_iter().flat_map(|rustc| {
-                    rustc.packages().map(move |krate| PackageRoot {
+                        let mut exclude = vec![pkg_root.join(".git")];
+                        if is_member {
+                            exclude.push(pkg_root.join("target"));
+                        } else {
+                            exclude.push(pkg_root.join("tests"));
+                            exclude.push(pkg_root.join("examples"));
+                            exclude.push(pkg_root.join("benches"));
+                        }
+                        PackageRoot { is_member, include, exclude }
+                    })
+                    .chain(sysroot.crates().map(|krate| PackageRoot {
                         is_member: false,
-                        include: vec![rustc[krate].root().to_path_buf()],
+                        include: vec![sysroot[krate].root_dir().to_path_buf()],
                         exclude: Vec::new(),
-                    })
-                }))
-                .collect(),
+                    }))
+                    .chain(rustc.into_iter().flat_map(|rustc| {
+                        rustc.packages().map(move |krate| PackageRoot {
+                            is_member: false,
+                            include: vec![rustc[krate].root().to_path_buf()],
+                            exclude: Vec::new(),
+                        })
+                    }))
+                    .collect()
+            }
             ProjectWorkspace::DetachedFiles { files, sysroot, .. } => files
                 .into_iter()
                 .map(|detached_file| PackageRoot {
@@ -299,16 +307,22 @@ impl ProjectWorkspace {
                 project,
                 sysroot,
             ),
-            ProjectWorkspace::Cargo { cargo, sysroot, rustc, rustc_cfg } => cargo_to_crate_graph(
-                rustc_cfg.clone(),
-                &proc_macro_loader,
-                load,
-                cargo,
-                build_data.and_then(|it| it.get(cargo.workspace_root())),
-                sysroot,
-                rustc,
-                rustc.as_ref().zip(build_data).and_then(|(it, map)| map.get(it.workspace_root())),
-            ),
+            ProjectWorkspace::Cargo { cargo, sysroot, rustc, rustc_cfg, cfg_overrides } => {
+                cargo_to_crate_graph(
+                    rustc_cfg.clone(),
+                    cfg_overrides,
+                    &proc_macro_loader,
+                    load,
+                    cargo,
+                    build_data.and_then(|it| it.get(cargo.workspace_root())),
+                    sysroot,
+                    rustc,
+                    rustc
+                        .as_ref()
+                        .zip(build_data)
+                        .and_then(|(it, map)| map.get(it.workspace_root())),
+                )
+            }
             ProjectWorkspace::DetachedFiles { files, sysroot, rustc_cfg } => {
                 detached_files_to_crate_graph(rustc_cfg.clone(), load, files, sysroot)
             }
@@ -398,6 +412,7 @@ fn project_json_to_crate_graph(
 
 fn cargo_to_crate_graph(
     rustc_cfg: Vec<CfgFlag>,
+    override_cfg: &CfgOverrides,
     proc_macro_loader: &dyn Fn(&Path) -> Vec<ProcMacro>,
     load: &mut dyn FnMut(&AbsPath) -> Option<FileId>,
     cargo: &CargoWorkspace,
@@ -425,6 +440,21 @@ fn cargo_to_crate_graph(
     let mut has_private = false;
     // Next, create crates for each package, target pair
     for pkg in cargo.packages() {
+        let mut cfg_options = &cfg_options;
+        let mut replaced_cfg_options;
+        if let Some(overrides) = override_cfg.get(&cargo[pkg].name) {
+            // FIXME: this is sort of a hack to deal with #![cfg(not(test))] vanishing such as seen
+            // in ed25519_dalek (#7243), and libcore (#9203) (although you only hit that one while
+            // working on rust-lang/rust as that's the only time it appears outside sysroot).
+            //
+            // A more ideal solution might be to reanalyze crates based on where the cursor is and
+            // figure out the set of cfgs that would have to apply to make it active.
+
+            replaced_cfg_options = cfg_options.clone();
+            replaced_cfg_options.apply_diff(overrides.clone());
+            cfg_options = &replaced_cfg_options;
+        };
+
         has_private |= cargo[pkg].metadata.rustc_private;
         let mut lib_tgt = None;
         for &tgt in cargo[pkg].targets.iter() {
diff --git a/crates/rust-analyzer/src/config.rs b/crates/rust-analyzer/src/config.rs
index 16c295639..7e0276c10 100644
--- a/crates/rust-analyzer/src/config.rs
+++ b/crates/rust-analyzer/src/config.rs
@@ -55,6 +55,8 @@ config_data! {
         cargo_autoreload: bool           = "true",
         /// Activate all available features (`--all-features`).
         cargo_allFeatures: bool          = "false",
+        /// Unsets `#[cfg(test)]` for the specified crates.
+        cargo_unsetTest: Vec<String>   = "[\"core\"]",
         /// List of features to activate.
         cargo_features: Vec<String>      = "[]",
         /// Run build scripts (`build.rs`) for more precise code analysis.
@@ -595,8 +597,10 @@ impl Config {
             target: self.data.cargo_target.clone(),
             rustc_source,
             no_sysroot: self.data.cargo_noSysroot,
+            unset_test_crates: self.data.cargo_unsetTest.clone(),
         }
     }
+
     pub fn rustfmt(&self) -> RustfmtConfig {
         match &self.data.rustfmt_overrideCommand {
             Some(args) if !args.is_empty() => {