Silence unwind cfg lint warnings

```
warning: unexpected `cfg` condition name: `unwind`
  --> src/python_spy.rs:38:11
   |
38 |     #[cfg(unwind)]
   |           ^^^^^^ help: found config with similar value: `panic =
"unwind"`
   |
   = help: consider using a Cargo feature instead
   = help: or consider adding in `Cargo.toml` the `check-cfg` lint
config for the lint:
            [lints.rust]
            unexpected_cfgs = { level = "warn", check-cfg =
['cfg(unwind)'] }
   = help: or consider adding
`println!("cargo::rustc-check-cfg=cfg(unwind)");` to the top of the
`build.rs`
   = note: see
<https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html>
for more information about checking conditional configuration
```

Cargo.toml

@@ -1,3 +1,6 @@
+[features]
+unwind = []
+
 [package]
 name = "py-spy"
 version = "0.3.14"

src/binary_parser.rs

@@ -17,7 +17,7 @@ pub struct BinaryInfo {
 }
 
 impl BinaryInfo {
-    #[cfg(unwind)]
+    #[cfg(feature = "unwind")]
     pub fn contains(&self, addr: u64) -> bool {
         addr >= self.addr && addr < (self.addr + self.size)
     }

src/config.rs

@@ -160,7 +160,7 @@ impl Config {
             .help("PID of a running python program to spy on")
             .takes_value(true);
 
-        #[cfg(unwind)]
+        #[cfg(feature = "unwind")]
         let native = Arg::new("native")
             .short('n')
             .long("native")
@@ -328,11 +328,11 @@ impl Config {
             );
 
         // add native unwinding if appropriate
-        #[cfg(unwind)]
+        #[cfg(feature = "unwind")]
         let record = record.arg(native.clone());
-        #[cfg(unwind)]
+        #[cfg(feature = "unwind")]
         let top = top.arg(native.clone());
-        #[cfg(unwind)]
+        #[cfg(feature = "unwind")]
         let dump = dump.arg(native.clone());
 
         // Nonblocking isn't an option for freebsd, remove
@@ -429,7 +429,7 @@ impl Config {
             .value_of("pid")
             .map(|p| p.parse().expect("invalid pid"));
         config.full_filenames = matches.occurrences_of("full_filenames") > 0;
-        if cfg!(unwind) {
+        if cfg!(feature = "unwind") {
             config.native = matches.occurrences_of("native") > 0;
         }
 

src/lib.rs

@@ -33,10 +33,10 @@ pub mod binary_parser;
 pub mod config;
 #[cfg(target_os = "linux")]
 pub mod coredump;
-#[cfg(unwind)]
+#[cfg(feature = "unwind")]
 mod cython;
 pub mod dump;
-#[cfg(unwind)]
+#[cfg(feature = "unwind")]
 mod native_stack_trace;
 mod python_bindings;
 mod python_data_access;

src/main.rs

@@ -9,11 +9,11 @@ mod config;
 mod console_viewer;
 #[cfg(target_os = "linux")]
 mod coredump;
-#[cfg(unwind)]
+#[cfg(feature = "unwind")]
 mod cython;
 mod dump;
 mod flamegraph;
-#[cfg(unwind)]
+#[cfg(feature = "unwind")]
 mod native_stack_trace;
 mod python_bindings;
 mod python_data_access;

src/python_spy.rs

@@ -1,17 +1,17 @@
 #[cfg(windows)]
 use regex::RegexBuilder;
 use std::collections::HashMap;
-#[cfg(all(target_os = "linux", unwind))]
+#[cfg(all(target_os = "linux", feature = "unwind"))]
 use std::collections::HashSet;
-#[cfg(all(target_os = "linux", unwind))]
+#[cfg(all(target_os = "linux", feature = "unwind"))]
 use std::iter::FromIterator;
 use std::path::Path;
 
 use anyhow::{Context, Error, Result};
 use remoteprocess::{Pid, Process, ProcessMemory, Tid};
 
 use crate::config::{Config, LockingStrategy};
-#[cfg(unwind)]
+#[cfg(feature = "unwind")]
 use crate::native_stack_trace::NativeStack;
 use crate::python_bindings::{
     v2_7_15, v3_10_0, v3_11_0, v3_3_7, v3_5_5, v3_6_6, v3_7_0, v3_8_0, v3_9_5,
@@ -35,7 +35,7 @@ pub struct PythonSpy {
     pub python_filename: std::path::PathBuf,
     pub version_string: String,
     pub config: Config,
-    #[cfg(unwind)]
+    #[cfg(feature = "unwind")]
     pub native: Option<NativeStack>,
     pub short_filenames: HashMap<String, Option<String>>,
     pub python_thread_ids: HashMap<u64, Tid>,
@@ -70,7 +70,7 @@ impl PythonSpy {
 
         let version_string = format!("python{}.{}", version.major, version.minor);
 
-        #[cfg(unwind)]
+        #[cfg(feature = "unwind")]
         let native = if config.native {
             Some(NativeStack::new(
                 pid,
@@ -89,7 +89,7 @@ impl PythonSpy {
             threadstate_address,
             python_filename: python_info.python_filename,
             version_string,
-            #[cfg(unwind)]
+            #[cfg(feature = "unwind")]
             native,
             #[cfg(target_os = "linux")]
             dockerized: python_info.dockerized,
@@ -291,7 +291,7 @@ impl PythonSpy {
             }
 
             // Merge in the native stack frames if necessary
-            #[cfg(unwind)]
+            #[cfg(feature = "unwind")]
             {
                 if self.config.native {
                     if let Some(native) = self.native.as_mut() {
@@ -389,7 +389,7 @@ impl PythonSpy {
         Ok(None)
     }
 
-    #[cfg(all(target_os = "linux", not(unwind)))]
+    #[cfg(all(target_os = "linux", not(feature = "unwind")))]
     fn _get_os_thread_id<I: InterpreterState>(
         &mut self,
         _python_thread_id: u64,
@@ -398,7 +398,7 @@ impl PythonSpy {
         Ok(None)
     }
 
-    #[cfg(all(target_os = "linux", unwind))]
+    #[cfg(all(target_os = "linux", feature = "unwind"))]
     fn _get_os_thread_id<I: InterpreterState>(
         &mut self,
         python_thread_id: u64,
@@ -483,7 +483,7 @@ impl PythonSpy {
         Ok(None)
     }
 
-    #[cfg(all(target_os = "linux", unwind))]
+    #[cfg(all(target_os = "linux", feature = "unwind"))]
     pub fn _get_pthread_id(
         &self,
         unwinder: &remoteprocess::Unwinder,

src/utils.rs

@@ -1,4 +1,4 @@
-#[cfg(unwind)]
+#[cfg(feature = "unwind")]
 pub fn resolve_filename(filename: &str, modulename: &str) -> Option<String> {
     // check the filename first, if it exists use it
     use std::path::Path;

tests/integration_test.rs

@@ -62,7 +62,7 @@ fn test_busy_loop() {
     assert!(traces[0].active);
 }
 
-#[cfg(unwind)]
+#[cfg(feature = "unwind")]
 #[test]
 fn test_thread_reuse() {
     // on linux we had an issue with the pthread -> native thread id caching