Add perlapi_verXX config attributes for conditional build

Author: hkoba

build.rs

@@ -5,4 +5,6 @@ fn main() {
     perl.emit_cargo_ldopts();
 
     perl.emit_features(&["useithreads"]);
+
+    perl.emit_perlapi_vers(10, 30);
 }

examples/102_padname_type.rs

@@ -1,18 +1,33 @@
 use std::env;
 
 use libperl_rs::perl::Perl;
-use libperl_sys;
+use libperl_sys::{cv, PADLIST, PADNAMELIST};
 
 #[cfg(perl_useithreads)]
-fn get_main_cv(perl: &Perl) -> *const libperl_sys::cv {
+fn get_main_cv(perl: &Perl) -> *const cv {
     unsafe {(*perl.my_perl)}.Imain_cv
 }
 
 #[cfg(not(perl_useithreads))]
-fn get_main_cv(_perl: &Perl) -> *const libperl_sys::cv {
+fn get_main_cv(_perl: &Perl) -> *const cv {
     unsafe {libperl_sys::PL_main_cv}
 }
 
+#[cfg(perlapi_ver24)]
+fn fetch_padnamelist(padlist: *const PADLIST) -> *const PADNAMELIST {
+    unsafe {
+        (*(*padlist).xpadl_arr.xpadlarr_dbg).padnl
+    }
+}
+
+#[cfg(not(perlapi_ver24))]
+fn fetch_padnamelist(padlist: *const PADLIST) -> *const PADNAMELIST {
+    unsafe {
+        *((*padlist).xpadl_alloc
+          as *const *const PADNAMELIST)
+    }
+}
+
 fn test() {
     let mut perl = Perl::new();
 
@@ -25,10 +40,7 @@ fn test() {
     print!("xpvcv = {:#?}\n", xpvcv);
     let padlist = unsafe {(*xpvcv).xcv_padlist_u.xcv_padlist};
     print!("padlist = {:#?}\n", padlist);
-    let padnamelist_ptr = unsafe {
-        *((*padlist).xpadl_arr.xpadlarr_alloc
-          as *const *const libperl_sys::PADNAMELIST)
-    };
+    let padnamelist_ptr = fetch_padnamelist(padlist);
     if let Some(padnamelist) = unsafe {padnamelist_ptr.as_ref()} {
         println!("padnamelist = {:?}", padnamelist);
         let mut ix: usize = 0;

libperl-config/src/perl_config.rs

@@ -56,6 +56,33 @@ impl PerlConfig {
         process_command_output(cmd.output()?)
     }
 
+    pub fn read_one_config(&self, configs: &[&str]) -> Result<String, Error> {
+        let script = ["-wle", r#"
+    use strict;
+    use Config;
+    print ($Config{shift()} // '');
+    "#
+        ];
+        let mut cmd = self.command(&[&script[..], configs].concat());
+
+        process_command_output(cmd.output()?)
+    }
+
+    pub fn emit_perlapi_vers(&self, min: i32, max: i32) {
+        let config = self.read_one_config(&["PERL_API_VERSION"]).unwrap();
+        let config = config.trim();
+        println!("# PERL_API_VERSION={}", config);
+        let ver = i32::from_str_radix(String::from(config).trim(), 10).unwrap();
+        for v in min..=max {
+            if v % 2 == 1 {
+                continue;
+            }
+            if ver >= v {
+                println!("cargo:rustc-cfg=perlapi_ver{}", v);
+            }
+        }
+    }
+
     pub fn emit_features(&self, configs: &[&str]) -> ConfigDict {
         let dict = self.read_config(&configs).unwrap();
 

libperl-sys/build.rs

@@ -35,7 +35,9 @@ fn main() {
     let ccopts = perl.read_ccopts().unwrap();
     println!("# perl ccopts = {:?}, ", ccopts);
 
-    perl.emit_features(&["useithreads"]);
+    perl.emit_features(&["useithreads"]); // "usemultiplicity"
+
+    perl.emit_perlapi_vers(10, 30);
 
     let src_file_name = "wrapper.h";
     let src_path = cargo_topdir_file(src_file_name);