1 //! Tidy check to enforce rules about platform-specific code in std.
3 //! This is intended to maintain existing standards of code
4 //! organization in hopes that the standard library will continue to
5 //! be refactored to isolate platform-specific bits, making porting
6 //! easier; where "standard library" roughly means "all the
7 //! dependencies of the std and test crates".
9 //! This generally means placing restrictions on where `cfg(unix)`,
10 //! `cfg(windows)`, `cfg(target_os)` and `cfg(target_env)` may appear,
11 //! the basic objective being to isolate platform-specific code to the
12 //! platform-specific `std::sys` modules, and to the allocation,
13 //! unwinding, and libc crates.
15 //! Following are the basic rules, though there are currently
18 //! - core may not have platform-specific code.
19 //! - libpanic_abort may have platform-specific code.
20 //! - libpanic_unwind may have platform-specific code.
21 //! - libunwind may have platform-specific code.
22 //! - other crates in the std facade may not.
23 //! - std may have platform-specific code in the following places:
27 //! `std/sys_common` should _not_ contain platform-specific code.
28 //! Finally, because std contains tests with platform-specific
29 //! `ignore` attributes, once the parser encounters `mod tests`,
30 //! platform-specific cfgs are allowed. Not sure yet how to deal with
31 //! this in the long term.
33 use crate::walk::{filter_dirs, walk};
34 use std::iter::Iterator;
37 // Paths that may contain platform-specific code.
38 const EXCEPTION_PATHS: &[&str] = &[
39 "library/panic_abort",
40 "library/panic_unwind",
42 "library/rtstartup", // Not sure what to do about this. magic stuff for mingw
43 "library/term", // Not sure how to make this crate portable, but test crate needs it.
44 "library/test", // Probably should defer to unstable `std::sys` APIs.
45 // The `VaList` implementation must have platform specific code.
46 // The Windows implementation of a `va_list` is always a character
47 // pointer regardless of the target architecture. As a result,
48 // we must use `#[cfg(windows)]` to conditionally compile the
49 // correct `VaList` structure for windows.
50 "library/core/src/ffi/mod.rs",
51 "library/std/src/sys/", // Platform-specific code for std lives here.
52 "library/std/src/os", // Platform-specific public interfaces
53 // Temporary `std` exceptions
54 // FIXME: platform-specific code should be moved to `sys`
55 "library/std/src/io/copy.rs",
56 "library/std/src/io/stdio.rs",
57 "library/std/src/f32.rs",
58 "library/std/src/f64.rs",
59 "library/std/src/path.rs",
60 "library/std/src/sys_common", // Should only contain abstractions over platforms
61 "library/std/src/net/test.rs", // Utility helpers for tests
62 "library/std/src/panic.rs", // fuchsia-specific panic backtrace handling
63 "library/std/src/personality.rs",
64 "library/std/src/personality/",
67 pub fn check(path: &Path, bad: &mut bool) {
68 // Sanity check that the complex parsing here works.
69 let mut saw_target_arch = false;
70 let mut saw_cfg_bang = false;
71 walk(path, &mut filter_dirs, &mut |entry, contents| {
72 let file = entry.path();
73 let filestr = file.to_string_lossy().replace("\\", "/");
74 if !filestr.ends_with(".rs") {
78 let is_exception_path = EXCEPTION_PATHS.iter().any(|s| filestr.contains(&**s));
79 if is_exception_path {
83 // exclude tests and benchmarks as some platforms do not support all tests
84 if filestr.contains("tests") || filestr.contains("benches") {
88 check_cfgs(contents, &file, bad, &mut saw_target_arch, &mut saw_cfg_bang);
91 assert!(saw_target_arch);
92 assert!(saw_cfg_bang);
99 saw_target_arch: &mut bool,
100 saw_cfg_bang: &mut bool,
102 // Pull out all `cfg(...)` and `cfg!(...)` strings.
103 let cfgs = parse_cfgs(contents);
105 let mut line_numbers: Option<Vec<usize>> = None;
106 let mut err = |idx: usize, cfg: &str| {
107 if line_numbers.is_none() {
108 line_numbers = Some(contents.match_indices('\n').map(|(i, _)| i).collect());
110 let line_numbers = line_numbers.as_ref().expect("");
111 let line = match line_numbers.binary_search(&idx) {
112 Ok(_) => unreachable!(),
115 tidy_error!(bad, "{}:{}: platform-specific cfg: {}", file.display(), line, cfg);
118 for (idx, cfg) in cfgs {
119 // Sanity check that the parsing here works.
120 if !*saw_target_arch && cfg.contains("target_arch") {
121 *saw_target_arch = true
123 if !*saw_cfg_bang && cfg.contains("cfg!") {
127 let contains_platform_specific_cfg = cfg.contains("target_os")
128 || cfg.contains("target_env")
129 || cfg.contains("target_abi")
130 || cfg.contains("target_vendor")
131 || cfg.contains("unix")
132 || cfg.contains("windows");
134 if !contains_platform_specific_cfg {
138 let preceded_by_doc_comment = {
139 let pre_contents = &contents[..idx];
140 let pre_newline = pre_contents.rfind('\n');
141 let pre_doc_comment = pre_contents.rfind("///");
142 match (pre_newline, pre_doc_comment) {
143 (Some(n), Some(c)) => n < c,
144 (None, Some(_)) => true,
149 if preceded_by_doc_comment {
153 // exclude tests as some platforms do not support all tests
154 if cfg.contains("test") {
162 fn parse_cfgs(contents: &str) -> Vec<(usize, &str)> {
163 let candidate_cfgs = contents.match_indices("cfg");
164 let candidate_cfg_idxs = candidate_cfgs.map(|(i, _)| i);
165 // This is puling out the indexes of all "cfg" strings
166 // that appear to be tokens followed by a parenthesis.
167 let cfgs = candidate_cfg_idxs.filter(|i| {
168 let pre_idx = i.saturating_sub(1);
169 let succeeds_non_ident = !contents
174 .map(char::is_alphanumeric)
176 let contents_after = &contents[*i..];
177 let first_paren = contents_after.find('(');
178 let paren_idx = first_paren.map(|ip| i + ip);
179 let preceeds_whitespace_and_paren = paren_idx
181 let maybe_space = &contents[*i + "cfg".len()..ip];
182 maybe_space.chars().all(|c| char::is_whitespace(c) || c == '!')
186 succeeds_non_ident && preceeds_whitespace_and_paren
191 let contents_from = &contents[i..];
192 for (j, byte) in contents_from.bytes().enumerate() {
200 return Some((i, &contents_from[..=j]));
207 // if the parentheses are unbalanced just ignore this cfg -- it'll be caught when attempting
208 // to run the compiler, and there's no real reason to lint it separately here