Add from docs for tools

Author: TimTheBig

src/tools/clippy/clippy_lints/src/attrs/mixed_attributes_style.rs

@@ -15,6 +15,10 @@ enum SimpleAttrKind {
 }
 
 impl From<&AttrKind> for SimpleAttrKind {
+    /// Convert an `AttrKind` to a `SimpleAttrKind`, if it's a `DocComment` then `Doc` is returned with no conversion.
+    ///
+    /// ## Cost
+    /// If `AttrKind` is `DocComment` it's free, however if it's `Normal` their is heep allocation
     fn from(value: &AttrKind) -> Self {
         match value {
             AttrKind::Normal(attr) => {

src/tools/miri/src/concurrency/thread.rs

@@ -80,6 +80,7 @@ impl Idx for ThreadId {
 }
 
 impl From<ThreadId> for u64 {
+    /// Return inner `u32` converted to `u64`
     fn from(t: ThreadId) -> Self {
         t.0.into()
     }

src/tools/miri/src/concurrency/vector_clock.rs

@@ -34,6 +34,7 @@ impl Idx for VectorIdx {
 }
 
 impl From<u32> for VectorIdx {
+    /// Create new `VectorIdx` with `u32` as inner
     #[inline]
     fn from(id: u32) -> Self {
         Self(id)

src/tools/miri/src/lib.rs

@@ -74,7 +74,7 @@ extern crate rustc_middle;
 extern crate rustc_session;
 extern crate rustc_span;
 extern crate rustc_target;
-// Linking `rustc_driver` pulls in the required  object code as the rest of the rustc crates are
+// Linking `rustc_driver` pulls in the required object code as the rest of the rustc crates are
 // shipped only as rmeta files.
 #[allow(unused_extern_crates)]
 extern crate rustc_driver;

src/tools/miri/src/shims/io_error.rs

@@ -14,18 +14,21 @@ pub enum IoError {
 pub use self::IoError::*;
 
 impl From<io::Error> for IoError {
+    /// Wrap `io::Error` in `HostError`
     fn from(value: io::Error) -> Self {
         IoError::HostError(value)
     }
 }
 
 impl From<io::ErrorKind> for IoError {
+    /// Convert a `io::ErrorKind` to a `io::Error` then wrap in `HostError`
     fn from(value: io::ErrorKind) -> Self {
         IoError::HostError(value.into())
     }
 }
 
 impl From<Scalar> for IoError {
+    /// Wrap `Scalar` in `Raw`
     fn from(value: Scalar) -> Self {
         IoError::Raw(value)
     }

src/tools/rust-analyzer/crates/base-db/src/input.rs

@@ -173,6 +173,8 @@ pub enum LangCrateOrigin {
 }
 
 impl From<&str> for LangCrateOrigin {
+    /// Match a string slice for "alloc", "core", "proc-macro", "proc_macro", "std", "test",
+    /// mapping them to variants of the same name; if none match then it's `Other`
     fn from(s: &str) -> Self {
         match s {
             "alloc" => LangCrateOrigin::Alloc,
@@ -217,6 +219,10 @@ impl CrateDisplayName {
 }
 
 impl From<CrateName> for CrateDisplayName {
+    /// Creates a `CrateDisplayName` from `crate_name` and `crate_name.0`(inner)
+    /// 
+    /// ## Cost
+    /// This clones `CrateName`
     fn from(crate_name: CrateName) -> CrateDisplayName {
         let canonical_name = crate_name.0.clone();
         CrateDisplayName { crate_name, canonical_name }
@@ -634,6 +640,10 @@ impl Env {
 }
 
 impl From<Env> for Vec<(String, String)> {
+    /// Iterates the hash map entries collects them in to a `Vec` then sorts it.
+    ///
+    /// ## Cost
+    /// This is expensive as it `collect`s and `sort`s env
     fn from(env: Env) -> Vec<(String, String)> {
         let mut entries: Vec<_> = env.entries.into_iter().collect();
         entries.sort();

src/tools/rust-analyzer/crates/cfg/src/cfg_expr.rs

@@ -38,6 +38,7 @@ pub enum CfgExpr {
 }
 
 impl From<CfgAtom> for CfgExpr {
+    /// Wrap `CfgAtom` in `CfgExpr::Atom`
     fn from(atom: CfgAtom) -> Self {
         CfgExpr::Atom(atom)
     }

src/tools/rust-analyzer/crates/hir-def/src/attr.rs

@@ -245,6 +245,7 @@ pub enum DocExpr {
 }
 
 impl From<DocAtom> for DocExpr {
+    /// Creates `Atom` with `DocAtom`
     fn from(atom: DocAtom) -> Self {
         DocExpr::Atom(atom)
     }

src/tools/rust-analyzer/crates/hir-def/src/hir.rs

@@ -146,6 +146,7 @@ impl Literal {
 }
 
 impl From<ast::LiteralKind> for Literal {
+    /// Create a `Literal` by matching `LiteralKind`
     fn from(ast_lit_kind: ast::LiteralKind) -> Self {
         use ast::LiteralKind;
         match ast_lit_kind {

src/tools/rust-analyzer/crates/hir-def/src/hir/type_ref.rs

@@ -637,6 +637,8 @@ impl LiteralConstRef {
 }
 
 impl From<Literal> for LiteralConstRef {
+    /// Make a `LiteralConstRef` from `Literal`
+    /// - Note: `Char`, `Bool`, `Int`, `Uint` match, other types are not const and return a `Unknown`
     fn from(literal: Literal) -> Self {
         match literal {
             Literal::Char(c) => Self::Char(c),