style(rust): clear cargo clippy -- -D warnings (the other half of Build Check) (#85)

## Why

`Build Check` runs **`cargo fmt --check` then `cargo clippy -- -D
warnings`** (`.github/workflows/security.yml:72-74`). On `main` the
*fmt* step failed first and **masked 31 pre-existing clippy errors**. PR
#84 fixes fmt; this PR clears the clippy half so the gate goes fully
green.

**Stacked on #84** (base = `claude/fix-rustfmt-nonconformity`) so this
PR's diff is **clippy-only** and its own `Build Check` can pass (it
needs the fmt fix present to get past the fmt step). When #84 merges,
GitHub auto-retargets this to `main`.

## What

- **Machine-applicable lints** via `cargo clippy --fix` across ~16 files
(needless borrows/clones, redundant `to_owned`, single-char string
patterns, `unused_enumerate_index`, …).
- **Hand-fixed** the non-machine-applicable ones — all
semantics-preserving:
  - `while_let_loop` → `src/interpreter/value.rs`
  - `manual_strip` ×2 → `src/stdlib/net.rs` (`strip_prefix`)
  - `needless_range_loop` → `src/stdlib/time.rs` (`.iter().take(..)`)
  - `collapsible_match` → `src/typechecker/mod.rs`
  - `unnecessary_to_owned` → `src/sexpr.rs`
  - `wildcard_in_or_patterns` → `src/main.rs`
- **`dead_code` scaffolding silenced, NOT deleted** (your call) with
`#[allow(dead_code)]` + a comment, since these look like reserved
scaffolding:
- `Precedence::Primary` (parser), `Parser::peek_next` (lookahead
helper), `vm::compiler` `Local.depth` (scope tracking).
- If you'd rather **delete** any of these, say so and I'll swap the
allow for removal.

## Verified locally

- `cargo fmt --check` — clean
- `cargo clippy -- -D warnings` — **exit 0**
- `cargo test --lib` — **173/173 pass** (confirms the
collapse/while-let/strip_prefix edits didn't change behavior)

⚠️ One caveat: local clippy is **1.94.1** while CI floats to **1.96.0**
(no toolchain pin; `.tool-versions` = `rust stable`). The fixes are
forward-compatible, but if 1.96 introduces a lint 1.94 doesn't flag, CI
may surface one more — I'll chase it if so. (A `rust-toolchain.toml` pin
would prevent this class of drift — worth a follow-up.)

https://claude.ai/code/session_013wg3Mtq2QFhYi4XVw1Z6z7

---
_Generated by [Claude
Code](https://claude.ai/code/session_013wg3Mtq2QFhYi4XVw1Z6z7)_

---------

Co-authored-by: Claude <noreply@anthropic.com>

Author: hyperpolymath

src/bin/woke-lsp.rs

@@ -17,7 +17,7 @@ async fn main() {
     let stdin = tokio::io::stdin();
     let stdout = tokio::io::stdout();
 
-    let (service, socket) = LspService::new(|client| Backend::new(client));
+    let (service, socket) = LspService::new(Backend::new);
 
     eprintln!("WokeLang LSP Server initialized");
 

src/bin/wokelang-dap.rs

@@ -4,7 +4,7 @@
 
 use std::io::{BufRead, BufReader, Write};
 use std::net::{TcpListener, TcpStream};
-use wokelang::dap::{DapRequest, DapResponse, DapServer};
+use wokelang::dap::{DapRequest, DapServer};
 
 fn main() -> Result<(), Box<dyn std::error::Error>> {
     let listener = TcpListener::bind("127.0.0.1:4712")?;

src/dap/mod.rs

@@ -6,7 +6,6 @@
 
 use serde::{Deserialize, Serialize};
 use std::collections::HashMap;
-use std::path::PathBuf;
 
 #[derive(Debug, Serialize, Deserialize)]
 pub struct DapRequest {
@@ -121,6 +120,12 @@ pub struct DapServer {
     pub variables: HashMap<String, String>,
 }
 
+impl Default for DapServer {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 impl DapServer {
     pub fn new() -> Self {
         Self {

src/formatter/mod.rs

@@ -6,7 +6,7 @@
 //! Provides AST-based code formatting with consistent style.
 
 use crate::ast::{Expr, Program, Statement, TopLevelItem};
-use crate::lexer::{Lexer, Spanned};
+use crate::lexer::Lexer;
 use crate::parser::Parser;
 
 /// Formatter for WokeLang code
@@ -96,7 +96,7 @@ impl Formatter {
                 output.push_str(&self.format_expr(&expr.node));
                 output.push_str(";\n");
             }
-            Statement::Return(ret_stmt) => {
+            Statement::Return(_ret_stmt) => {
                 output.push_str(&indent_str);
                 output.push_str("give back ...;\n");
             }

src/interpreter/mod.rs

@@ -776,7 +776,7 @@ impl Interpreter {
                         })
                     }
                     _ => Err(RuntimeError {
-                        message: format!("Cannot access field of non-record value"),
+                        message: "Cannot access field of non-record value".to_string(),
                     }),
                 }
             }

src/interpreter/value.rs

@@ -180,14 +180,9 @@ impl ChannelHandle {
         let receiver = self.receiver.lock().unwrap();
         let mut count = 0usize;
         let mut drained = Vec::new();
-        loop {
-            match receiver.try_recv() {
-                Ok(val) => {
-                    drained.push(val);
-                    count += 1;
-                }
-                Err(_) => break,
-            }
+        while let Ok(val) = receiver.try_recv() {
+            drained.push(val);
+            count += 1;
         }
         // Put them back via the sender
         for val in drained {

src/linter/mod.rs

@@ -83,7 +83,7 @@ impl Linter {
 
     fn lint_function(&mut self, func: &FunctionDef) {
         // Check function name style
-        if !func.name.chars().next().map_or(false, |c| c.is_lowercase()) {
+        if !func.name.chars().next().is_some_and(|c| c.is_lowercase()) {
             self.diagnostics.push(Diagnostic {
                 severity: Severity::Warning,
                 message: format!("Function '{}' should start with lowercase", func.name),

src/main.rs

@@ -402,7 +402,8 @@ fn parse_file(file: &PathBuf, format: &str) -> Result<()> {
             "sexpr" | "sexp" => {
                 println!("{}", sexpr::program_to_sexpr(&program));
             }
-            "pretty" | _ => {
+            // "pretty" is the default for any unrecognised format
+            _ => {
                 println!("{:#?}", program);
                 println!(
                     "\nParsed {} top-level items successfully.",

src/parser/mod.rs

@@ -55,6 +55,8 @@ enum Precedence {
     Factor = 6,     // * / %
     Unary = 7,      // - not
     Call = 8,       // f(x) arr[i]
+    // Highest precedence; kept for ladder completeness (not constructed directly yet).
+    #[allow(dead_code)]
     Primary = 9,
 }
 
@@ -97,6 +99,7 @@ impl<'a> Parser<'a> {
     }
 
     /// Peek at next token (lookahead)
+    #[allow(dead_code)] // lookahead helper retained for upcoming grammar rules
     fn peek_next(&self) -> &Token {
         if self.current + 1 < self.tokens.len() {
             &self.tokens[self.current + 1].value
@@ -199,7 +202,7 @@ impl<'a> Parser<'a> {
     }
 
     fn parse_precedence(&mut self, precedence: Precedence) -> Result<Spanned<Expr>, ParseError> {
-        let start = self.current_span().start;
+        let _start = self.current_span().start;
 
         // Parse prefix expression
         let mut expr = self.parse_prefix()?;
@@ -711,7 +714,7 @@ impl<'a> Parser<'a> {
             while !matches!(self.peek(), Token::RBrace) && !self.is_at_end() {
                 stmts.push(self.parse_statement()?);
             }
-            let end_span = self.expect(Token::RBrace, "}")?;
+            let _end_span = self.expect(Token::RBrace, "}")?;
             Some(stmts)
         } else {
             None
@@ -989,7 +992,7 @@ impl<'a> Parser<'a> {
                 self.advance();
 
                 // Check if it's a constructor pattern (capitalized identifier followed by optional parens)
-                if name.chars().next().map_or(false, |c| c.is_uppercase()) {
+                if name.chars().next().is_some_and(|c| c.is_uppercase()) {
                     if self.match_tokens(&[Token::LParen]) {
                         let inner = self.parse_pattern()?;
                         self.expect(Token::RParen, ")")?;

src/security/mod.rs

@@ -218,7 +218,7 @@ impl CapabilityRegistry {
 
         self.capabilities
             .entry(scope.to_string())
-            .or_insert_with(Vec::new)
+            .or_default()
             .push(entry);
 
         self.audit(capability, AuditAction::Granted, scope, true);
@@ -237,7 +237,7 @@ impl CapabilityRegistry {
 
         self.capabilities
             .entry(scope.to_string())
-            .or_insert_with(Vec::new)
+            .or_default()
             .push(entry);
 
         self.audit(capability, AuditAction::Granted, scope, true);