Add "--no-default [regex]" flag

Add a command line flag "--no-default [regex]" which ensures that any
types matching "[regex]" will neither derive nor Impl Default.

Add the corresponding builder command "no_default(regex)" which has the
same behavior for invocations of bindgen via Builder.

Author: fletcherw

src/ir/analysis/derive.rs

@@ -454,6 +454,7 @@ impl DeriveTrait {
     fn not_by_name(&self, ctx: &BindgenContext, item: &Item) -> bool {
         match self {
             DeriveTrait::Copy => ctx.no_copy_by_name(item),
+            DeriveTrait::Default => ctx.no_default_by_name(item),
             DeriveTrait::Hash => ctx.no_hash_by_name(item),
             DeriveTrait::PartialEqOrPartialOrd => {
                 ctx.no_partialeq_by_name(item)

src/ir/context.rs

@@ -2627,6 +2627,12 @@ If you encounter an error missing from this list, please file an issue or a PR!"
         let name = item.path_for_whitelisting(self)[1..].join("::");
         self.options().no_hash_types.matches(&name)
     }
+
+    /// Check if `--no-default` flag is enabled for this item.
+    pub fn no_default_by_name(&self, item: &Item) -> bool {
+        let name = item.path_for_whitelisting(self)[1..].join("::");
+        self.options().no_default_types.matches(&name)
+    }
 }
 
 /// A builder struct for configuring item resolution options.

src/lib.rs

@@ -586,6 +586,16 @@ impl Builder {
             })
             .count();
 
+        self.options
+            .no_default_types
+            .get_items()
+            .iter()
+            .map(|item| {
+                output_vector.push("--no-default".into());
+                output_vector.push(item.to_owned());
+            })
+            .count();
+
         output_vector
     }
 
@@ -1361,6 +1371,13 @@ impl Builder {
         self.options.array_pointers_in_arguments = doit;
         self
     }
+
+    /// Don't derive `Default` for a given type. Regular
+    /// expressions are supported.
+    pub fn no_default<T: Into<String>>(mut self, arg: T) -> Builder {
+        self.options.no_default_types.insert(arg.into());
+        self
+    }
 }
 
 /// Configuration options for generated bindings.
@@ -1600,6 +1617,9 @@ struct BindgenOptions {
 
     /// Decide if C arrays should be regular pointers in rust or array pointers
     array_pointers_in_arguments: bool,
+
+    /// The set of types that we should not derive `Default` for.
+    no_default_types: RegexSet,
 }
 
 /// TODO(emilio): This is sort of a lie (see the error message that results from
@@ -1625,6 +1645,7 @@ impl BindgenOptions {
             &mut self.no_partialeq_types,
             &mut self.no_copy_types,
             &mut self.no_hash_types,
+            &mut self.no_default_types,
         ];
         let record_matches = self.record_matches;
         for regex_set in &mut regex_sets {
@@ -1715,6 +1736,7 @@ impl Default for BindgenOptions {
             no_copy_types: Default::default(),
             no_hash_types: Default::default(),
             array_pointers_in_arguments: false,
+            no_default_types: Default::default(),
         }
     }
 }

src/options.rs

@@ -378,6 +378,13 @@ where
             Arg::with_name("use-array-pointers-in-arguments")
                 .long("use-array-pointers-in-arguments")
                 .help("Use `*const [T; size]` instead of `*const T` for C arrays"),
+            Arg::with_name("no-default")
+                .long("no-default")
+                .help("Avoids deriving Default for types matching <regex>.")
+                .value_name("regex")
+                .takes_value(true)
+                .multiple(true)
+                .number_of_values(1),
         ]) // .args()
         .get_matches_from(args);
 
@@ -713,6 +720,12 @@ where
         }
     }
 
+    if let Some(no_default) = matches.values_of("no-default") {
+        for regex in no_default {
+            builder = builder.no_default(regex);
+        }
+    }
+
     let verbose = matches.is_present("verbose");
 
     Ok((builder, output, verbose))

tests/expectations/tests/forward-no-default.rs

@@ -0,0 +1,15 @@
+/* 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 NoDefault {
+    _unused: [u8; 0],
+}
+pub type NoDefaultT = NoDefault;

tests/expectations/tests/no-default-opaque.rs

@@ -0,0 +1,28 @@
+/* automatically generated by rust-bindgen */
+
+#![allow(
+    dead_code,
+    non_snake_case,
+    non_camel_case_types,
+    non_upper_case_globals
+)]
+
+#[repr(C)]
+#[repr(align(4))]
+#[derive(Debug, Copy, Clone)]
+pub struct NoDefault {
+    pub _bindgen_opaque_blob: u32,
+}
+#[test]
+fn bindgen_test_layout_NoDefault() {
+    assert_eq!(
+        ::std::mem::size_of::<NoDefault>(),
+        4usize,
+        concat!("Size of: ", stringify!(NoDefault))
+    );
+    assert_eq!(
+        ::std::mem::align_of::<NoDefault>(),
+        4usize,
+        concat!("Alignment of ", stringify!(NoDefault))
+    );
+}

tests/expectations/tests/no-default-whitelisted.rs

@@ -0,0 +1,37 @@
+/* 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 NoDefault {
+    pub x: ::std::os::raw::c_int,
+}
+#[test]
+fn bindgen_test_layout_NoDefault() {
+    assert_eq!(
+        ::std::mem::size_of::<NoDefault>(),
+        4usize,
+        concat!("Size of: ", stringify!(NoDefault))
+    );
+    assert_eq!(
+        ::std::mem::align_of::<NoDefault>(),
+        4usize,
+        concat!("Alignment of ", stringify!(NoDefault))
+    );
+    assert_eq!(
+        unsafe { &(*(::std::ptr::null::<NoDefault>())).x as *const _ as usize },
+        0usize,
+        concat!(
+            "Offset of field: ",
+            stringify!(NoDefault),
+            "::",
+            stringify!(x)
+        )
+    );
+}

tests/expectations/tests/no-default.rs

@@ -0,0 +1,39 @@
+/* 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 NotDefault {
+    pub x: ::std::os::raw::c_int,
+}
+#[test]
+fn bindgen_test_layout_NotDefault() {
+    assert_eq!(
+        ::std::mem::size_of::<NotDefault>(),
+        4usize,
+        concat!("Size of: ", stringify!(NotDefault))
+    );
+    assert_eq!(
+        ::std::mem::align_of::<NotDefault>(),
+        4usize,
+        concat!("Alignment of ", stringify!(NotDefault))
+    );
+    assert_eq!(
+        unsafe {
+            &(*(::std::ptr::null::<NotDefault>())).x as *const _ as usize
+        },
+        0usize,
+        concat!(
+            "Offset of field: ",
+            stringify!(NotDefault),
+            "::",
+            stringify!(x)
+        )
+    );
+}

tests/expectations/tests/whitelisted-item-references-no-default.rs

@@ -0,0 +1,57 @@
+/* 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 NoDefault {
+    pub _address: u8,
+}
+#[test]
+fn bindgen_test_layout_NoDefault() {
+    assert_eq!(
+        ::std::mem::size_of::<NoDefault>(),
+        1usize,
+        concat!("Size of: ", stringify!(NoDefault))
+    );
+    assert_eq!(
+        ::std::mem::align_of::<NoDefault>(),
+        1usize,
+        concat!("Alignment of ", stringify!(NoDefault))
+    );
+}
+#[repr(C)]
+#[derive(Debug, Copy, Clone)]
+pub struct Whitelisted {
+    pub x: NoDefault,
+}
+#[test]
+fn bindgen_test_layout_Whitelisted() {
+    assert_eq!(
+        ::std::mem::size_of::<Whitelisted>(),
+        1usize,
+        concat!("Size of: ", stringify!(Whitelisted))
+    );
+    assert_eq!(
+        ::std::mem::align_of::<Whitelisted>(),
+        1usize,
+        concat!("Alignment of ", stringify!(Whitelisted))
+    );
+    assert_eq!(
+        unsafe {
+            &(*(::std::ptr::null::<Whitelisted>())).x as *const _ as usize
+        },
+        0usize,
+        concat!(
+            "Offset of field: ",
+            stringify!(Whitelisted),
+            "::",
+            stringify!(x)
+        )
+    );
+}

tests/headers/forward-no-default.h

@@ -0,0 +1,3 @@
+// bindgen-flags: --no-default NoDefault
+
+typedef struct NoDefault NoDefaultT;

tests/headers/no-default-opaque.hpp

@@ -0,0 +1,7 @@
+// bindgen-flags: --no-default "NoDefault" --opaque-type "NoDefault"
+
+// `--with-derive-default` is added by the test runner implicitly.
+
+class NoDefault {
+    int x;
+};

tests/headers/no-default-whitelisted.hpp

@@ -0,0 +1,7 @@
+// bindgen-flags: --no-default "NoDefault" --whitelist-type "NoDefault"
+
+// `--with-derive-default` is added by the test runner implicitly.
+
+class NoDefault {
+    int x;
+};

tests/headers/no-default.hpp

@@ -0,0 +1,7 @@
+// bindgen-flags: --no-default "NotDefault"
+
+// `--with-derive-default` is added by the test runner implicitly.
+
+class NotDefault {
+    int x;
+};

tests/headers/whitelisted-item-references-no-default.hpp

@@ -0,0 +1,9 @@
+// bindgen-flags: --no-default "NoDefault" --whitelist-type "Whitelisted"
+
+// `--with-derive-default` is added by the test runner implicitly.
+
+struct NoDefault {};
+
+class Whitelisted {
+    NoDefault x;
+};