options: Add an opt-in to recover the size_t behavior removed in 5d38f2a.

Author: emilio

src/codegen/mod.rs

@@ -4126,8 +4126,14 @@ mod utils {
             "int64_t" => primitive_ty(ctx, "i64"),
             "uint64_t" => primitive_ty(ctx, "u64"),
 
+            "size_t" if ctx.options().size_t_is_usize => {
+                primitive_ty(ctx, "usize")
+            }
             "uintptr_t" => primitive_ty(ctx, "usize"),
 
+            "ssize_t" if ctx.options().size_t_is_usize => {
+                primitive_ty(ctx, "isize")
+            }
             "intptr_t" | "ptrdiff_t" => primitive_ty(ctx, "isize"),
             _ => return None,
         })

src/lib.rs

@@ -604,6 +604,10 @@ impl Builder {
             output_vector.push("--no-record-matches".into());
         }
 
+        if self.options.size_t_is_usize {
+            output_vector.push("--size_t-is-usize".into());
+        }
+
         if !self.options.rustfmt_bindings {
             output_vector.push("--no-rustfmt-bindings".into());
         }
@@ -1350,6 +1354,12 @@ impl Builder {
         self
     }
 
+    /// Set whether `size_t` should be translated to `usize` automatically.
+    pub fn size_t_is_usize(mut self, is: bool) -> Self {
+        self.options.size_t_is_usize = is;
+        self
+    }
+
     /// Set whether rustfmt should format the generated bindings.
     pub fn rustfmt_bindings(mut self, doit: bool) -> Self {
         self.options.rustfmt_bindings = doit;
@@ -1776,6 +1786,9 @@ struct BindgenOptions {
     /// items via the `error!` log.
     record_matches: bool,
 
+    /// Whether `size_t` should be translated to `usize` automatically.
+    size_t_is_usize: bool,
+
     /// Whether rustfmt should format the generated bindings.
     rustfmt_bindings: bool,
 
@@ -1917,6 +1930,7 @@ impl Default for BindgenOptions {
             time_phases: false,
             record_matches: true,
             rustfmt_bindings: true,
+            size_t_is_usize: false,
             rustfmt_configuration_file: None,
             no_partialeq_types: Default::default(),
             no_copy_types: Default::default(),

src/options.rs

@@ -383,6 +383,9 @@ where
                     "Do not record matching items in the regex sets. \
                      This disables reporting of unused items.",
                 ),
+            Arg::with_name("size_t-is-usize")
+                .long("size_t-is-usize")
+                .help("Translate size_t to usize."),
             Arg::with_name("no-rustfmt-bindings")
                 .long("no-rustfmt-bindings")
                 .help("Do not format the generated bindings with rustfmt."),
@@ -763,6 +766,10 @@ where
         builder = builder.record_matches(false);
     }
 
+    if matches.is_present("size_t-is-usize") {
+        builder = builder.size_t_is_usize(true);
+    }
+
     let no_rustfmt_bindings = matches.is_present("no-rustfmt-bindings");
     if no_rustfmt_bindings {
         builder = builder.rustfmt_bindings(false);

tests/expectations/tests/size_t_is_usize.rs

@@ -0,0 +1,49 @@
+/* automatically generated by rust-bindgen */
+
+#![allow(
+    dead_code,
+    non_snake_case,
+    non_camel_case_types,
+    non_upper_case_globals
+)]
+
+#[repr(C)]
+#[derive(Debug, Copy, Clone)]
+pub struct A {
+    pub len: usize,
+    pub offset: isize,
+    pub next: *mut A,
+}
+#[test]
+fn bindgen_test_layout_A() {
+    assert_eq!(
+        ::std::mem::size_of::<A>(),
+        24usize,
+        concat!("Size of: ", stringify!(A))
+    );
+    assert_eq!(
+        ::std::mem::align_of::<A>(),
+        8usize,
+        concat!("Alignment of ", stringify!(A))
+    );
+    assert_eq!(
+        unsafe { &(*(::std::ptr::null::<A>())).len as *const _ as usize },
+        0usize,
+        concat!("Offset of field: ", stringify!(A), "::", stringify!(len))
+    );
+    assert_eq!(
+        unsafe { &(*(::std::ptr::null::<A>())).offset as *const _ as usize },
+        8usize,
+        concat!("Offset of field: ", stringify!(A), "::", stringify!(offset))
+    );
+    assert_eq!(
+        unsafe { &(*(::std::ptr::null::<A>())).next as *const _ as usize },
+        16usize,
+        concat!("Offset of field: ", stringify!(A), "::", stringify!(next))
+    );
+}
+impl Default for A {
+    fn default() -> Self {
+        unsafe { ::std::mem::zeroed() }
+    }
+}

tests/headers/size_t_is_usize.h

@@ -0,0 +1,10 @@
+// bindgen-flags: --size_t-is-usize
+
+typedef unsigned long size_t;
+typedef long ssize_t;
+
+struct A {
+  size_t len;
+  ssize_t offset;
+  struct A* next;
+};