Canonicalize types before looking for their definitions.

In some esoteric cases involving nested templates,
`ty.declaration().definition()` isn't enough to find the definition: we need
`ty.canonical_type().declaration().definition()` instead.

Closes rust-lang#2078.

Author: pcwalton

src/ir/item.rs

@@ -1594,8 +1594,8 @@ impl ClangItemParser for Item {
         }
 
         let decl = {
-            let decl = ty.declaration();
-            decl.definition().unwrap_or(decl)
+            let canonical_def = ty.canonical_type().declaration().definition();
+            canonical_def.unwrap_or_else(|| ty.declaration())
         };
 
         let comment = decl.raw_comment().or_else(|| location.raw_comment());

tests/expectations/tests/canonical-types.rs

@@ -0,0 +1,278 @@
+#![allow(
+    dead_code,
+    non_snake_case,
+    non_camel_case_types,
+    non_upper_case_globals
+)]
+
+#[repr(C)]
+#[derive(Debug, Default, Copy, Clone)]
+pub struct ClassA {
+    pub _address: u8,
+}
+#[repr(C)]
+#[derive(Debug, Copy, Clone)]
+pub struct ClassA_ClassAInner<T> {
+    pub x: *mut T,
+    pub _phantom_0: ::std::marker::PhantomData<::std::cell::UnsafeCell<T>>,
+}
+impl<T> Default for ClassA_ClassAInner<T> {
+    fn default() -> Self {
+        let mut s = ::std::mem::MaybeUninit::<Self>::uninit();
+        unsafe {
+            ::std::ptr::write_bytes(s.as_mut_ptr(), 0, 1);
+            s.assume_init()
+        }
+    }
+}
+#[repr(C)]
+#[derive(Debug, Default, Copy, Clone)]
+pub struct ClassB {
+    pub _address: u8,
+}
+#[repr(C)]
+#[derive(Debug, Default, Copy, Clone)]
+pub struct ClassC {
+    pub _address: u8,
+}
+#[repr(C)]
+#[derive(Debug, Copy, Clone)]
+pub struct ClassC_ClassCInnerB {
+    pub cache: *mut ClassC_ClassCInnerA,
+}
+impl Default for ClassC_ClassCInnerB {
+    fn default() -> Self {
+        let mut s = ::std::mem::MaybeUninit::<Self>::uninit();
+        unsafe {
+            ::std::ptr::write_bytes(s.as_mut_ptr(), 0, 1);
+            s.assume_init()
+        }
+    }
+}
+#[repr(C)]
+#[derive(Debug, Copy, Clone)]
+pub struct ClassC_ClassCInnerA {
+    pub member: *mut ClassC_ClassCInnerB,
+}
+impl Default for ClassC_ClassCInnerA {
+    fn default() -> Self {
+        let mut s = ::std::mem::MaybeUninit::<Self>::uninit();
+        unsafe {
+            ::std::ptr::write_bytes(s.as_mut_ptr(), 0, 1);
+            s.assume_init()
+        }
+    }
+}
+#[repr(C)]
+#[derive(Debug, Copy, Clone)]
+pub struct ClassC_ClassCInnerCRTP {
+    pub _address: u8,
+}
+impl Default for ClassC_ClassCInnerCRTP {
+    fn default() -> Self {
+        let mut s = ::std::mem::MaybeUninit::<Self>::uninit();
+        unsafe {
+            ::std::ptr::write_bytes(s.as_mut_ptr(), 0, 1);
+            s.assume_init()
+        }
+    }
+}
+#[repr(C)]
+#[derive(Debug, Copy, Clone)]
+pub struct ClassD {
+    pub _address: u8,
+}
+#[test]
+fn bindgen_test_layout_ClassD() {
+    assert_eq!(
+        ::std::mem::size_of::<ClassD>(),
+        1usize,
+        concat!("Size of: ", stringify!(ClassD))
+    );
+    assert_eq!(
+        ::std::mem::align_of::<ClassD>(),
+        1usize,
+        concat!("Alignment of ", stringify!(ClassD))
+    );
+}
+impl Default for ClassD {
+    fn default() -> Self {
+        let mut s = ::std::mem::MaybeUninit::<Self>::uninit();
+        unsafe {
+            ::std::ptr::write_bytes(s.as_mut_ptr(), 0, 1);
+            s.assume_init()
+        }
+    }
+}
+#[test]
+fn __bindgen_test_layout_ClassB_open0_ClassD_ClassCInnerCRTP_close0_instantiation(
+) {
+    assert_eq!(
+        ::std::mem::size_of::<ClassB>(),
+        1usize,
+        concat!("Size of template specialization: ", stringify!(ClassB))
+    );
+    assert_eq!(
+        ::std::mem::align_of::<ClassB>(),
+        1usize,
+        concat!("Alignment of template specialization: ", stringify!(ClassB))
+    );
+}
+#[repr(C)]
+#[derive(Debug, Copy, Clone)]
+pub struct ClassCInnerCRTP {
+    pub _address: u8,
+}
+#[test]
+fn bindgen_test_layout_ClassCInnerCRTP() {
+    assert_eq!(
+        ::std::mem::size_of::<ClassCInnerCRTP>(),
+        1usize,
+        concat!("Size of: ", stringify!(ClassCInnerCRTP))
+    );
+    assert_eq!(
+        ::std::mem::align_of::<ClassCInnerCRTP>(),
+        1usize,
+        concat!("Alignment of ", stringify!(ClassCInnerCRTP))
+    );
+}
+impl Default for ClassCInnerCRTP {
+    fn default() -> Self {
+        let mut s = ::std::mem::MaybeUninit::<Self>::uninit();
+        unsafe {
+            ::std::ptr::write_bytes(s.as_mut_ptr(), 0, 1);
+            s.assume_init()
+        }
+    }
+}
+#[test]
+fn __bindgen_test_layout_ClassB_open0_ClassCInnerCRTP_ClassAInner_close0_instantiation(
+) {
+    assert_eq!(
+        ::std::mem::size_of::<ClassB>(),
+        1usize,
+        concat!("Size of template specialization: ", stringify!(ClassB))
+    );
+    assert_eq!(
+        ::std::mem::align_of::<ClassB>(),
+        1usize,
+        concat!("Alignment of template specialization: ", stringify!(ClassB))
+    );
+}
+#[repr(C)]
+#[derive(Debug, Copy, Clone)]
+pub struct ClassAInner {
+    pub x: *mut ClassCInnerA,
+}
+#[test]
+fn bindgen_test_layout_ClassAInner() {
+    assert_eq!(
+        ::std::mem::size_of::<ClassAInner>(),
+        8usize,
+        concat!("Size of: ", stringify!(ClassAInner))
+    );
+    assert_eq!(
+        ::std::mem::align_of::<ClassAInner>(),
+        8usize,
+        concat!("Alignment of ", stringify!(ClassAInner))
+    );
+    assert_eq!(
+        unsafe {
+            &(*(::std::ptr::null::<ClassAInner>())).x as *const _ as usize
+        },
+        0usize,
+        concat!(
+            "Offset of field: ",
+            stringify!(ClassAInner),
+            "::",
+            stringify!(x)
+        )
+    );
+}
+impl Default for ClassAInner {
+    fn default() -> Self {
+        let mut s = ::std::mem::MaybeUninit::<Self>::uninit();
+        unsafe {
+            ::std::ptr::write_bytes(s.as_mut_ptr(), 0, 1);
+            s.assume_init()
+        }
+    }
+}
+#[repr(C)]
+#[derive(Debug, Copy, Clone)]
+pub struct ClassCInnerA {
+    pub member: *mut ClassCInnerB,
+}
+#[test]
+fn bindgen_test_layout_ClassCInnerA() {
+    assert_eq!(
+        ::std::mem::size_of::<ClassCInnerA>(),
+        8usize,
+        concat!("Size of: ", stringify!(ClassCInnerA))
+    );
+    assert_eq!(
+        ::std::mem::align_of::<ClassCInnerA>(),
+        8usize,
+        concat!("Alignment of ", stringify!(ClassCInnerA))
+    );
+    assert_eq!(
+        unsafe {
+            &(*(::std::ptr::null::<ClassCInnerA>())).member as *const _ as usize
+        },
+        0usize,
+        concat!(
+            "Offset of field: ",
+            stringify!(ClassCInnerA),
+            "::",
+            stringify!(member)
+        )
+    );
+}
+impl Default for ClassCInnerA {
+    fn default() -> Self {
+        let mut s = ::std::mem::MaybeUninit::<Self>::uninit();
+        unsafe {
+            ::std::ptr::write_bytes(s.as_mut_ptr(), 0, 1);
+            s.assume_init()
+        }
+    }
+}
+#[repr(C)]
+#[derive(Debug, Copy, Clone)]
+pub struct ClassCInnerB {
+    pub cache: *mut ClassCInnerA,
+}
+#[test]
+fn bindgen_test_layout_ClassCInnerB() {
+    assert_eq!(
+        ::std::mem::size_of::<ClassCInnerB>(),
+        8usize,
+        concat!("Size of: ", stringify!(ClassCInnerB))
+    );
+    assert_eq!(
+        ::std::mem::align_of::<ClassCInnerB>(),
+        8usize,
+        concat!("Alignment of ", stringify!(ClassCInnerB))
+    );
+    assert_eq!(
+        unsafe {
+            &(*(::std::ptr::null::<ClassCInnerB>())).cache as *const _ as usize
+        },
+        0usize,
+        concat!(
+            "Offset of field: ",
+            stringify!(ClassCInnerB),
+            "::",
+            stringify!(cache)
+        )
+    );
+}
+impl Default for ClassCInnerB {
+    fn default() -> Self {
+        let mut s = ::std::mem::MaybeUninit::<Self>::uninit();
+        unsafe {
+            ::std::ptr::write_bytes(s.as_mut_ptr(), 0, 1);
+            s.assume_init()
+        }
+    }
+}

tests/expectations/tests/layout_cmdline_token.rs

@@ -61,6 +61,8 @@ impl Default for cmdline_token_hdr {
         }
     }
 }
+/// Stores a pointer to the ops struct, and the offset: the place to
+/// write the parsed result in the destination structure.
 pub type cmdline_parse_token_hdr_t = cmdline_token_hdr;
 /// A token is defined by this structure.
 ///

tests/headers/canonical-types.hpp

@@ -0,0 +1,51 @@
+// bindgen-flags: -- -std=c++14
+
+// Issue #2078. To pick up the definition of `ClassCInnerA`,
+// `ty.canonical_type().declaration().definition()` is needed.
+
+template<class T>
+class ClassA {
+public:
+    class ClassAInner {
+    public:
+        T *x;
+    };
+};
+
+template<class D, class I>
+class ClassB {
+public:
+    void foo() {
+        ((D *)0)->quux();
+    }
+};
+
+template<typename T>
+class ClassC {
+    struct ClassCInnerA;
+
+    struct ClassCInnerB {
+        ClassCInnerA *cache;
+    };
+    static_assert(sizeof(ClassCInnerB) > 0, "");
+
+    struct ClassCInnerA {
+        ClassCInnerB *member;
+    };
+
+public:
+    class ClassCInnerCRTP : public ClassB<ClassCInnerCRTP, typename ClassA<ClassCInnerA>::ClassAInner> {
+    public:
+        void quux() {
+            ((typename ClassA<ClassCInnerA>::ClassAInner *)0)->x->member;
+        }
+    };
+};
+
+class ClassD : public ClassB<ClassD, ClassC<int>::ClassCInnerCRTP> {
+public:
+    void bar() {
+        ((ClassC<int>::ClassCInnerCRTP *)0)->foo();
+    }
+};
+