Merge pull request #1521 from ravenexp/remove-header-parsing

Remove `pyconfig.h` header parsing

Author: kngwyu

CHANGELOG.md

@@ -37,6 +37,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
   - `PyObject_Check`, `PySuper_Check`, and `FreeFunc` [#1438](https://github.com/PyO3/pyo3/pull/1438)
 - Remove pyclass implementation details `Type`, `DESCRIPTION`, and `FLAGS` from `PyTypeInfo`. [#1456](https://github.com/PyO3/pyo3/pull/1456)
 - Remove `__doc__` from module's `__all__`. [#1509](https://github.com/PyO3/pyo3/pull/1509)
+- Remove `PYO3_CROSS_INCLUDE_DIR` environment variable and the associated C header parsing functionality.
 
 ### Fixed
 - Remove FFI definition `PyCFunction_ClearFreeList` for Python 3.9 and later. [#1425](https://github.com/PyO3/pyo3/pull/1425)

build.rs

@@ -2,8 +2,8 @@ use std::{
     collections::{HashMap, HashSet},
     convert::AsRef,
     env,
-    fs::{self, DirEntry, File},
-    io::{self, BufRead, BufReader},
+    fs::{self, DirEntry},
+    io,
     path::{Path, PathBuf},
     process::{Command, Stdio},
     str::FromStr,
@@ -109,24 +109,15 @@ impl GetPrimitive for HashMap<String, String> {
 
 struct CrossCompileConfig {
     lib_dir: PathBuf,
-    include_dir: Option<PathBuf>,
     version: Option<String>,
     os: String,
     arch: String,
 }
 
 impl CrossCompileConfig {
-    fn both() -> Result<Self> {
-        Ok(CrossCompileConfig {
-            include_dir: env::var_os("PYO3_CROSS_INCLUDE_DIR").map(Into::into),
-            ..CrossCompileConfig::lib_only()?
-        })
-    }
-
-    fn lib_only() -> Result<Self> {
+    fn new() -> Result<Self> {
         Ok(CrossCompileConfig {
             lib_dir: CrossCompileConfig::validate_variable("PYO3_CROSS_LIB_DIR")?,
-            include_dir: None,
             os: env::var("CARGO_CFG_TARGET_OS").unwrap(),
             arch: env::var("CARGO_CFG_TARGET_ARCH").unwrap(),
             version: env::var_os("PYO3_CROSS_PYTHON_VERSION").map(|s| s.into_string().unwrap()),
@@ -183,13 +174,8 @@ fn cross_compiling() -> Result<Option<CrossCompileConfig>> {
         return Ok(None);
     }
 
-    if env::var("CARGO_CFG_TARGET_FAMILY")? == "windows" {
-        // Windows cross-compile uses both header includes and sysconfig
-        return Ok(Some(CrossCompileConfig::both()?));
-    }
-
     // Cross-compiling on any other platform
-    Ok(Some(CrossCompileConfig::lib_only()?))
+    Ok(Some(CrossCompileConfig::new()?))
 }
 
 /// A list of python interpreter compile-time preprocessor defines that
@@ -300,23 +286,6 @@ impl BuildFlags {
     }
 }
 
-/// Attempts to parse the header at the given path, returning a map of definitions to their values.
-/// Each entry in the map directly corresponds to a `#define` in the given header.
-fn parse_header_defines(header_path: impl AsRef<Path>) -> Result<HashMap<String, String>> {
-    let header_reader = BufReader::new(File::open(header_path.as_ref())?);
-    let mut definitions = HashMap::new();
-    for maybe_line in header_reader.lines() {
-        let line = maybe_line?;
-        let mut i = line.trim().split_whitespace();
-        if i.next() == Some("#define") {
-            if let (Some(key), Some(value), None) = (i.next(), i.next(), i.next()) {
-                definitions.insert(key.into(), value.into());
-            }
-        }
-    }
-    Ok(definitions)
-}
-
 fn parse_script_output(output: &str) -> HashMap<String, String> {
     output
         .lines()
@@ -500,36 +469,6 @@ fn load_cross_compile_from_sysconfigdata(
     Ok((interpreter_config, build_flags))
 }
 
-fn load_cross_compile_from_headers(
-    cross_compile_config: CrossCompileConfig,
-) -> Result<(InterpreterConfig, BuildFlags)> {
-    let python_include_dir = cross_compile_config.include_dir.unwrap();
-    let python_include_dir = Path::new(&python_include_dir);
-    let patchlevel_defines = parse_header_defines(python_include_dir.join("patchlevel.h"))?;
-
-    let major = patchlevel_defines.get_numeric("PY_MAJOR_VERSION")?;
-    let minor = patchlevel_defines.get_numeric("PY_MINOR_VERSION")?;
-
-    let python_version = PythonVersion { major, minor };
-
-    let config_data = parse_header_defines(python_include_dir.join("pyconfig.h"))?;
-
-    let interpreter_config = InterpreterConfig {
-        version: python_version,
-        libdir: cross_compile_config.lib_dir.to_str().map(String::from),
-        shared: config_data.get_bool("Py_ENABLE_SHARED").unwrap_or(false),
-        ld_version: format!("{}.{}", major, minor),
-        base_prefix: "".to_string(),
-        executable: PathBuf::new(),
-        calcsize_pointer: None,
-        implementation: PythonInterpreterKind::CPython,
-    };
-
-    let build_flags = BuildFlags::from_config_map(&config_data);
-
-    Ok((interpreter_config, build_flags))
-}
-
 fn windows_hardcoded_cross_compile(
     cross_compile_config: CrossCompileConfig,
 ) -> Result<(InterpreterConfig, BuildFlags)> {
@@ -549,7 +488,7 @@ fn windows_hardcoded_cross_compile(
     } else if let Some(minor_version) = get_abi3_minor_version() {
         (3, minor_version)
     } else {
-        bail!("One of PYO3_CROSS_INCLUDE_DIR, PYO3_CROSS_PYTHON_VERSION, or an abi3-py3* feature must be specified when cross-compiling for Windows.")
+        bail!("PYO3_CROSS_PYTHON_VERSION or an abi3-py3* feature must be specified when cross-compiling for Windows.")
     };
 
     let python_version = PythonVersion { major, minor };
@@ -576,9 +515,6 @@ fn load_cross_compile_info(
     if target_family == "unix" {
         // Configure for unix platforms using the sysconfigdata file
         load_cross_compile_from_sysconfigdata(cross_compile_config)
-    } else if cross_compile_config.include_dir.is_some() {
-        // Must configure by headers on windows platform
-        load_cross_compile_from_headers(cross_compile_config)
     } else {
         windows_hardcoded_cross_compile(cross_compile_config)
     }

guide/src/building_and_distribution.md

@@ -84,17 +84,13 @@ Cross compiling PyO3 modules is relatively straightforward and requires a few pi
 * The appropriate options in your Cargo `.config` for the platform you're targeting and the toolchain you are using.
 * A Python interpreter that's already been compiled for your target.
 * A Python interpreter that is built for your host and available through the `PATH` or setting the [`PYO3_PYTHON`](#python-version) variable.
-* The headers that match the above interpreter.
 
-See https://github.com/japaric/rust-cross for a primer on cross compiling Rust in general.
+See [github.com/japaric/rust-cross](https://github.com/japaric/rust-cross) for a primer on cross compiling Rust in general.
 
 After you've obtained the above, you can build a cross compiled PyO3 module by setting a few extra environment variables:
 
-* `PYO3_CROSS_LIB_DIR`: This variable must be set to the directory containing the target's libpython DSO and the associated `_sysconfigdata*.py` file.
-* `PYO3_CROSS_PYTHON_VERSION`: Major and minor version (e.g. 3.9) of the target Python installation. This variable is only needed if pyo3 cannot determine the version to target by other means:
-  - From `PYO3_CROSS_INCLUDE_DIR` or abi3-py3* features when targeting Windows, or
-  - if there are multiple versions of python present in `PYO3_CROSS_LIB_DIR` when targeting unix.
-* `PYO3_CROSS_INCLUDE_DIR`: This variable can optionally be set to the directory containing the headers for the target's Python interpreter when targeting Windows.
+* `PYO3_CROSS_LIB_DIR`: This variable must be set to the directory containing the target's libpython DSO and the associated `_sysconfigdata*.py` file for Unix-like targets, or the Python DLL import libraries for the Windows target.
+* `PYO3_CROSS_PYTHON_VERSION`: Major and minor version (e.g. 3.9) of the target Python installation. This variable is only needed if PyO3 cannot determine the version to target from `abi3-py3*` features, or if there are multiple versions of Python present in `PYO3_CROSS_LIB_DIR`.
 
 An example might look like the following (assuming your target's sysroot is at `/home/pyo3/cross/sysroot` and that your target is `armv7`):
 
@@ -112,14 +108,16 @@ export PYO3_CROSS_LIB_DIR="/home/pyo3/cross/sysroot/usr/lib"
 cargo build --target armv7-unknown-linux-gnueabihf
 ```
 
-Or another example with the same sys root but building for windows:
+Or another example with the same sys root but building for Windows:
 ```sh
-export PYO3_CROSS_INCLUDE_DIR="/home/pyo3/cross/sysroot/usr/include"
+export PYO3_CROSS_PYTHON_VERSION=3.9
 export PYO3_CROSS_LIB_DIR="/home/pyo3/cross/sysroot/usr/lib"
 
 cargo build --target x86_64-pc-windows-gnu
 ```
 
+Any of the `abi3-py3*` features can be enabled instead of setting `PYO3_CROSS_PYTHON_VERSION` in the above examples.
+
 ## Bazel
 
 For an example of how to build python extensions using Bazel, see https://github.com/TheButlah/rules_pyo3