Enable a few more clippy lints by default (bytecodealliance#9038)

Also set their default levels to `warn` instead of `deny` to assist with
using clippy locally to avoid compilation failures and collecting as
many as possible in one run. Note that CI will still deny-by-default
through `-Dwarnings`.

Author: alexcrichton

Cargo.toml

@@ -176,7 +176,10 @@ unused-lifetimes = 'warn'
 # they're all turned off by default. Selective lints are then enabled below as
 # necessary.
 all = { level = 'allow', priority = -1 }
-clone_on_copy = 'deny'
+clone_on_copy = 'warn'
+map_clone = 'warn'
+unnecessary_to_owned = 'warn'
+manual_strip = 'warn'
 
 [workspace.dependencies]
 arbitrary = { version = "1.3.1" }

cranelift/codegen/src/ir/immediates.rs

@@ -218,9 +218,9 @@ fn parse_u64(s: &str) -> Result<u64, &'static str> {
 
     if s.starts_with("-0x") {
         return Err("Invalid character in hexadecimal number");
-    } else if s.starts_with("0x") {
+    } else if let Some(num) = s.strip_prefix("0x") {
         // Hexadecimal.
-        for ch in s[2..].chars() {
+        for ch in num.chars() {
             match ch.to_digit(16) {
                 Some(digit) => {
                     digits += 1;
@@ -934,10 +934,10 @@ fn parse_float(s: &str, w: u8, t: u8) -> Result<u128, &'static str> {
     debug_assert!(1 + w + t <= 128, "Too large IEEE format for u128");
     debug_assert!((t + w + 1).is_power_of_two(), "Unexpected IEEE format size");
 
-    let (sign_bit, s2) = if s.starts_with('-') {
-        (1u128 << (t + w), &s[1..])
-    } else if s.starts_with('+') {
-        (0, &s[1..])
+    let (sign_bit, s2) = if let Some(num) = s.strip_prefix('-') {
+        (1u128 << (t + w), num)
+    } else if let Some(num) = s.strip_prefix('+') {
+        (0, num)
     } else {
         (0, s)
     };
@@ -959,18 +959,18 @@ fn parse_float(s: &str, w: u8, t: u8) -> Result<u128, &'static str> {
             // Canonical quiet NaN: e = max, t = quiet.
             return Ok(sign_bit | max_e_bits | quiet_bit);
         }
-        if s2.starts_with("NaN:0x") {
+        if let Some(nan) = s2.strip_prefix("NaN:0x") {
             // Quiet NaN with payload.
-            return match u128::from_str_radix(&s2[6..], 16) {
+            return match u128::from_str_radix(nan, 16) {
                 Ok(payload) if payload < quiet_bit => {
                     Ok(sign_bit | max_e_bits | quiet_bit | payload)
                 }
                 _ => Err("Invalid NaN payload"),
             };
         }
-        if s2.starts_with("sNaN:0x") {
+        if let Some(nan) = s2.strip_prefix("sNaN:0x") {
             // Signaling NaN with payload.
-            return match u128::from_str_radix(&s2[7..], 16) {
+            return match u128::from_str_radix(nan, 16) {
                 Ok(payload) if 0 < payload && payload < quiet_bit => {
                     Ok(sign_bit | max_e_bits | payload)
                 }

cranelift/codegen/src/isa/aarch64/lower/isle.rs

@@ -63,7 +63,7 @@ pub(crate) fn lower_branch(
     // TODO: reuse the ISLE context across lowerings so we can reuse its
     // internal heap allocations.
     let mut isle_ctx = IsleContext { lower_ctx, backend };
-    generated_code::constructor_lower_branch(&mut isle_ctx, branch, &targets.to_vec())
+    generated_code::constructor_lower_branch(&mut isle_ctx, branch, targets)
 }
 
 pub struct ExtendedValue {

cranelift/codegen/src/isa/riscv64/lower/isle.rs

@@ -647,5 +647,5 @@ pub(crate) fn lower_branch(
     // TODO: reuse the ISLE context across lowerings so we can reuse its
     // internal heap allocations.
     let mut isle_ctx = RV64IsleContext::new(lower_ctx, backend);
-    generated_code::constructor_lower_branch(&mut isle_ctx, branch, &targets.to_vec())
+    generated_code::constructor_lower_branch(&mut isle_ctx, branch, targets)
 }

cranelift/codegen/src/isa/s390x/lower/isle.rs

@@ -74,7 +74,7 @@ pub(crate) fn lower_branch(
     // TODO: reuse the ISLE context across lowerings so we can reuse its
     // internal heap allocations.
     let mut isle_ctx = IsleContext { lower_ctx, backend };
-    generated_code::constructor_lower_branch(&mut isle_ctx, branch, &targets.to_vec())
+    generated_code::constructor_lower_branch(&mut isle_ctx, branch, targets)
 }
 
 impl generated_code::Context for IsleContext<'_, '_, MInst, S390xBackend> {

cranelift/codegen/src/isa/x64/lower/isle.rs

@@ -65,7 +65,7 @@ pub(crate) fn lower_branch(
     // TODO: reuse the ISLE context across lowerings so we can reuse its
     // internal heap allocations.
     let mut isle_ctx = IsleContext { lower_ctx, backend };
-    generated_code::constructor_lower_branch(&mut isle_ctx, branch, &targets.to_vec())
+    generated_code::constructor_lower_branch(&mut isle_ctx, branch, &targets)
 }
 
 impl Context for IsleContext<'_, '_, MInst, X64Backend> {

cranelift/codegen/src/machinst/pcc.rs

@@ -11,7 +11,7 @@ pub(crate) fn get_fact_or_default<I: VCodeInst>(vcode: &VCode<I>, reg: Reg, widt
     );
     vcode
         .vreg_fact(reg.into())
-        .map(|f| f.clone())
+        .cloned()
         .unwrap_or_else(|| Fact::max_range_for_width(width))
 }
 

cranelift/filetests/src/match_directive.rs

@@ -10,11 +10,7 @@ pub fn match_directive<'a>(comment: &'a str, directive: &str) -> Option<&'a str>
         "Directive must include trailing colon"
     );
     let text = comment.trim_start_matches(';').trim_start();
-    if text.starts_with(directive) {
-        Some(text[directive.len()..].trim())
-    } else {
-        None
-    }
+    text.strip_prefix(directive).map(|s| s.trim())
 }
 
 #[test]

cranelift/reader/src/parser.rs

@@ -788,9 +788,9 @@ impl<'a> Parser<'a> {
         if let Some(Token::Integer(text)) = self.token() {
             self.consume();
             // Lexer just gives us raw text that looks like an integer.
-            if text.starts_with("0x") {
+            if let Some(num) = text.strip_prefix("0x") {
                 // Parse it as a u8 in hexadecimal form.
-                u8::from_str_radix(&text[2..], 16)
+                u8::from_str_radix(num, 16)
                     .map_err(|_| self.error("unable to parse u8 as a hexadecimal immediate"))
             } else {
                 // Parse it as a u8 to check for overflow and other issues.

crates/environ/src/fact/signature.rs

@@ -40,7 +40,7 @@ impl ComponentTypesBuilder {
         let results = match self.flatten_types(
             &options.options,
             MAX_FLAT_RESULTS,
-            self[ty.results].types.iter().map(|ty| *ty),
+            self[ty.results].types.iter().copied(),
         ) {
             Some(list) => list,
             None => {