internal: move diagnostics to hir

The idea here is to eventually get rid of `dyn Diagnostic` and
`DiagnosticSink` infrastructure altogether, and just have a `enum
hir::Diagnostic` instead.

The problem with `dyn Diagnostic` is that it is defined in the lowest
level of the stack (hir_expand), but is used by the highest level (ide).

As a first step, we free hir_expand and hir_def from `dyn Diagnostic`
and kick the can up to `hir_ty`, as an intermediate state. The plan is
then to move DiagnosticSink similarly to the hir crate, and, as final
third step, remove its usage from the ide.

One currently unsolved problem is testing. You can notice that the test
which checks precise diagnostic ranges, unresolved_import_in_use_tree,
was moved to the ide layer. Logically, only IDE should have the infra to
render a specific range.

At the same time, the range is determined with the data produced in
hir_def and hir crates, so this layering is rather unfortunate. Working
on hir_def shouldn't require compiling `ide` for testing.

Author: matklad

crates/hir/src/diagnostics.rs

@@ -3,13 +3,227 @@
 //!
 //! This probably isn't the best way to do this -- ideally, diagnistics should
 //! be expressed in terms of hir types themselves.
-pub use hir_def::diagnostics::{
-    InactiveCode, UnresolvedMacroCall, UnresolvedModule, UnresolvedProcMacro,
-};
-pub use hir_expand::diagnostics::{
-    Diagnostic, DiagnosticCode, DiagnosticSink, DiagnosticSinkBuilder,
-};
-pub use hir_ty::diagnostics::{
-    IncorrectCase, MismatchedArgCount, MissingFields, MissingMatchArms, MissingOkOrSomeInTailExpr,
-    NoSuchField, RemoveThisSemicolon, ReplaceFilterMapNextWithFindMap,
+use std::any::Any;
+
+use cfg::{CfgExpr, CfgOptions, DnfExpr};
+use hir_def::path::ModPath;
+use hir_expand::{HirFileId, InFile};
+use stdx::format_to;
+use syntax::{ast, AstPtr, SyntaxNodePtr, TextRange};
+
+pub use hir_ty::{
+    diagnostics::{
+        IncorrectCase, MismatchedArgCount, MissingFields, MissingMatchArms,
+        MissingOkOrSomeInTailExpr, NoSuchField, RemoveThisSemicolon,
+        ReplaceFilterMapNextWithFindMap,
+    },
+    diagnostics_sink::{Diagnostic, DiagnosticCode, DiagnosticSink, DiagnosticSinkBuilder},
 };
+
+// Diagnostic: unresolved-module
+//
+// This diagnostic is triggered if rust-analyzer is unable to discover referred module.
+#[derive(Debug)]
+pub struct UnresolvedModule {
+    pub file: HirFileId,
+    pub decl: AstPtr<ast::Module>,
+    pub candidate: String,
+}
+
+impl Diagnostic for UnresolvedModule {
+    fn code(&self) -> DiagnosticCode {
+        DiagnosticCode("unresolved-module")
+    }
+    fn message(&self) -> String {
+        "unresolved module".to_string()
+    }
+    fn display_source(&self) -> InFile<SyntaxNodePtr> {
+        InFile::new(self.file, self.decl.clone().into())
+    }
+    fn as_any(&self) -> &(dyn Any + Send + 'static) {
+        self
+    }
+}
+
+// Diagnostic: unresolved-extern-crate
+//
+// This diagnostic is triggered if rust-analyzer is unable to discover referred extern crate.
+#[derive(Debug)]
+pub struct UnresolvedExternCrate {
+    pub file: HirFileId,
+    pub item: AstPtr<ast::ExternCrate>,
+}
+
+impl Diagnostic for UnresolvedExternCrate {
+    fn code(&self) -> DiagnosticCode {
+        DiagnosticCode("unresolved-extern-crate")
+    }
+    fn message(&self) -> String {
+        "unresolved extern crate".to_string()
+    }
+    fn display_source(&self) -> InFile<SyntaxNodePtr> {
+        InFile::new(self.file, self.item.clone().into())
+    }
+    fn as_any(&self) -> &(dyn Any + Send + 'static) {
+        self
+    }
+}
+
+#[derive(Debug)]
+pub struct UnresolvedImport {
+    pub file: HirFileId,
+    pub node: AstPtr<ast::UseTree>,
+}
+
+impl Diagnostic for UnresolvedImport {
+    fn code(&self) -> DiagnosticCode {
+        DiagnosticCode("unresolved-import")
+    }
+    fn message(&self) -> String {
+        "unresolved import".to_string()
+    }
+    fn display_source(&self) -> InFile<SyntaxNodePtr> {
+        InFile::new(self.file, self.node.clone().into())
+    }
+    fn as_any(&self) -> &(dyn Any + Send + 'static) {
+        self
+    }
+    fn is_experimental(&self) -> bool {
+        // This currently results in false positives in the following cases:
+        // - `cfg_if!`-generated code in libstd (we don't load the sysroot correctly)
+        // - `core::arch` (we don't handle `#[path = "../<path>"]` correctly)
+        // - proc macros and/or proc macro generated code
+        true
+    }
+}
+
+// Diagnostic: unresolved-macro-call
+//
+// This diagnostic is triggered if rust-analyzer is unable to resolve the path to a
+// macro in a macro invocation.
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct UnresolvedMacroCall {
+    pub file: HirFileId,
+    pub node: AstPtr<ast::MacroCall>,
+    pub path: ModPath,
+}
+
+impl Diagnostic for UnresolvedMacroCall {
+    fn code(&self) -> DiagnosticCode {
+        DiagnosticCode("unresolved-macro-call")
+    }
+    fn message(&self) -> String {
+        format!("unresolved macro `{}!`", self.path)
+    }
+    fn display_source(&self) -> InFile<SyntaxNodePtr> {
+        InFile::new(self.file, self.node.clone().into())
+    }
+    fn as_any(&self) -> &(dyn Any + Send + 'static) {
+        self
+    }
+    fn is_experimental(&self) -> bool {
+        true
+    }
+}
+
+// Diagnostic: inactive-code
+//
+// This diagnostic is shown for code with inactive `#[cfg]` attributes.
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct InactiveCode {
+    pub file: HirFileId,
+    pub node: SyntaxNodePtr,
+    pub cfg: CfgExpr,
+    pub opts: CfgOptions,
+}
+
+impl Diagnostic for InactiveCode {
+    fn code(&self) -> DiagnosticCode {
+        DiagnosticCode("inactive-code")
+    }
+    fn message(&self) -> String {
+        let inactive = DnfExpr::new(self.cfg.clone()).why_inactive(&self.opts);
+        let mut buf = "code is inactive due to #[cfg] directives".to_string();
+
+        if let Some(inactive) = inactive {
+            format_to!(buf, ": {}", inactive);
+        }
+
+        buf
+    }
+    fn display_source(&self) -> InFile<SyntaxNodePtr> {
+        InFile::new(self.file, self.node.clone())
+    }
+    fn as_any(&self) -> &(dyn Any + Send + 'static) {
+        self
+    }
+}
+
+// Diagnostic: unresolved-proc-macro
+//
+// This diagnostic is shown when a procedural macro can not be found. This usually means that
+// procedural macro support is simply disabled (and hence is only a weak hint instead of an error),
+// but can also indicate project setup problems.
+//
+// If you are seeing a lot of "proc macro not expanded" warnings, you can add this option to the
+// `rust-analyzer.diagnostics.disabled` list to prevent them from showing. Alternatively you can
+// enable support for procedural macros (see `rust-analyzer.procMacro.enable`).
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct UnresolvedProcMacro {
+    pub file: HirFileId,
+    pub node: SyntaxNodePtr,
+    /// If the diagnostic can be pinpointed more accurately than via `node`, this is the `TextRange`
+    /// to use instead.
+    pub precise_location: Option<TextRange>,
+    pub macro_name: Option<String>,
+}
+
+impl Diagnostic for UnresolvedProcMacro {
+    fn code(&self) -> DiagnosticCode {
+        DiagnosticCode("unresolved-proc-macro")
+    }
+
+    fn message(&self) -> String {
+        match &self.macro_name {
+            Some(name) => format!("proc macro `{}` not expanded", name),
+            None => "proc macro not expanded".to_string(),
+        }
+    }
+
+    fn display_source(&self) -> InFile<SyntaxNodePtr> {
+        InFile::new(self.file, self.node.clone())
+    }
+
+    fn as_any(&self) -> &(dyn Any + Send + 'static) {
+        self
+    }
+}
+
+// Diagnostic: macro-error
+//
+// This diagnostic is shown for macro expansion errors.
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct MacroError {
+    pub file: HirFileId,
+    pub node: SyntaxNodePtr,
+    pub message: String,
+}
+
+impl Diagnostic for MacroError {
+    fn code(&self) -> DiagnosticCode {
+        DiagnosticCode("macro-error")
+    }
+    fn message(&self) -> String {
+        self.message.clone()
+    }
+    fn display_source(&self) -> InFile<SyntaxNodePtr> {
+        InFile::new(self.file, self.node.clone())
+    }
+    fn as_any(&self) -> &(dyn Any + Send + 'static) {
+        self
+    }
+    fn is_experimental(&self) -> bool {
+        // Newly added and not very well-tested, might contain false positives.
+        true
+    }
+}