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:
28 //! `std/sys_common` should _not_ contain platform-specific code.
29 //! Finally, because std contains tests with platform-specific
30 //! `ignore` attributes, once the parser encounters `mod tests`,
31 //! platform-specific cfgs are allowed. Not sure yet how to deal with
32 //! this in the long term.
34 use std::iter::Iterator;
37 // Paths that may contain platform-specific code.
38 const EXCEPTION_PATHS: &[&str] = &[
41 "src/libpanic_unwind",
43 // black_box implementation is LLVM-version specific and it uses
44 // target_os to tell targets with different LLVM-versions appart
45 // (e.g. `wasm32-unknown-emscripten` vs `wasm32-unknown-unknown`):
46 "src/libcore/hint.rs",
47 "src/libstd/sys/", // Platform-specific code for std lives here.
48 // This has the trailing slash so that sys_common is not excepted.
49 "src/libstd/os", // Platform-specific public interfaces
50 "src/rtstartup", // Not sure what to do about this. magic stuff for mingw
51 // temporary exceptions
56 // Integration test for platform-specific run-time feature detection:
57 "src/libstd/tests/run-time-detect.rs",
58 "src/libstd/net/test.rs",
59 "src/libstd/sys_common/mod.rs",
60 "src/libstd/sys_common/net.rs",
61 "src/libstd/sys_common/backtrace.rs",
63 "src/libstd/panicking.rs",
64 "src/libterm", // Not sure how to make this crate portable, but test crate needs it.
65 "src/libtest", // Probably should defer to unstable `std::sys` APIs.
66 "src/libstd/sync/mpsc", // some tests are only run on non-emscripten
67 // std testing crates, okay for now at least
69 "src/liballoc/tests/lib.rs",
70 // The `VaList` implementation must have platform specific code.
71 // The Windows implementation of a `va_list` is always a character
72 // pointer regardless of the target architecture. As a result,
73 // we must use `#[cfg(windows)]` to conditionally compile the
74 // correct `VaList` structure for windows.
85 pub fn check(path: &Path, bad: &mut bool) {
86 // Sanity check that the complex parsing here works.
87 let mut saw_target_arch = false;
88 let mut saw_cfg_bang = false;
89 super::walk(path, &mut super::filter_dirs, &mut |entry, contents| {
90 let file = entry.path();
91 let filestr = file.to_string_lossy().replace("\\", "/");
92 if !filestr.ends_with(".rs") {
96 let is_exception_path = EXCEPTION_PATHS.iter().any(|s| filestr.contains(&**s));
97 if is_exception_path {
101 check_cfgs(contents, &file, bad, &mut saw_target_arch, &mut saw_cfg_bang);
104 assert!(saw_target_arch);
105 assert!(saw_cfg_bang);
112 saw_target_arch: &mut bool,
113 saw_cfg_bang: &mut bool,
115 // For now it's ok to have platform-specific code after 'mod tests'.
116 let mod_tests_idx = find_test_mod(contents);
117 let contents = &contents[..mod_tests_idx];
118 // Pull out all `cfg(...)` and `cfg!(...)` strings.
119 let cfgs = parse_cfgs(contents);
121 let mut line_numbers: Option<Vec<usize>> = None;
122 let mut err = |idx: usize, cfg: &str| {
123 if line_numbers.is_none() {
124 line_numbers = Some(contents.match_indices('\n').map(|(i, _)| i).collect());
126 let line_numbers = line_numbers.as_ref().expect("");
127 let line = match line_numbers.binary_search(&idx) {
128 Ok(_) => unreachable!(),
131 tidy_error!(bad, "{}:{}: platform-specific cfg: {}", file.display(), line, cfg);
134 for (idx, cfg) in cfgs {
135 // Sanity check that the parsing here works.
136 if !*saw_target_arch && cfg.contains("target_arch") {
137 *saw_target_arch = true
139 if !*saw_cfg_bang && cfg.contains("cfg!") {
143 let contains_platform_specific_cfg = cfg.contains("target_os")
144 || cfg.contains("target_env")
145 || cfg.contains("target_vendor")
146 || cfg.contains("unix")
147 || cfg.contains("windows");
149 if !contains_platform_specific_cfg {
153 let preceeded_by_doc_comment = {
154 let pre_contents = &contents[..idx];
155 let pre_newline = pre_contents.rfind('\n');
156 let pre_doc_comment = pre_contents.rfind("///");
157 match (pre_newline, pre_doc_comment) {
158 (Some(n), Some(c)) => n < c,
159 (None, Some(_)) => true,
164 if preceeded_by_doc_comment {
172 fn find_test_mod(contents: &str) -> usize {
173 if let Some(mod_tests_idx) = contents.find("mod tests") {
174 // Also capture a previous line indicating that "mod tests" is cfg'd out.
175 let prev_newline_idx = contents[..mod_tests_idx].rfind('\n').unwrap_or(mod_tests_idx);
176 let prev_newline_idx = contents[..prev_newline_idx].rfind('\n');
177 if let Some(nl) = prev_newline_idx {
178 let prev_line = &contents[nl + 1..mod_tests_idx];
179 if prev_line.contains("cfg(all(test, not(target_os")
180 || prev_line.contains("cfg(all(test, not(any(target_os")
194 fn parse_cfgs<'a>(contents: &'a str) -> Vec<(usize, &'a str)> {
195 let candidate_cfgs = contents.match_indices("cfg");
196 let candidate_cfg_idxs = candidate_cfgs.map(|(i, _)| i);
197 // This is puling out the indexes of all "cfg" strings
198 // that appear to be tokens followed by a parenthesis.
199 let cfgs = candidate_cfg_idxs.filter(|i| {
200 let pre_idx = i.saturating_sub(*i);
201 let succeeds_non_ident = !contents
206 .map(char::is_alphanumeric)
208 let contents_after = &contents[*i..];
209 let first_paren = contents_after.find('(');
210 let paren_idx = first_paren.map(|ip| i + ip);
211 let preceeds_whitespace_and_paren = paren_idx
213 let maybe_space = &contents[*i + "cfg".len()..ip];
214 maybe_space.chars().all(|c| char::is_whitespace(c) || c == '!')
218 succeeds_non_ident && preceeds_whitespace_and_paren
223 let contents_from = &contents[i..];
224 for (j, byte) in contents_from.bytes().enumerate() {
232 return Some((i, &contents_from[..=j]));
239 // if the parentheses are unbalanced just ignore this cfg -- it'll be caught when attempting
240 // to run the compiler, and there's no real reason to lint it separately here