diff --git a/src/bindgen/declarationtyperesolver.rs b/src/bindgen/declarationtyperesolver.rs
index bbdca17..e72761e 100644
--- a/src/bindgen/declarationtyperesolver.rs
+++ b/src/bindgen/declarationtyperesolver.rs
@@ -2,23 +2,9 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use std::collections::HashSet;
-
 use crate::bindgen::ir::Path;
-
-#[derive(Default)]
-pub struct DeclarationTypeResolver {
-    structs: HashSet<Path>,
-    enums: HashSet<Path>,
-    unions: HashSet<Path>,
-}
-
-#[derive(Clone, Copy, PartialEq, PartialOrd, Eq, Ord, Debug, Hash)]
-pub enum DeclarationType {
-    Struct,
-    Enum,
-    Union,
-}
+use std::collections::hash_map::Entry;
+use std::collections::HashMap;
 
 impl DeclarationType {
     pub fn to_str(self) -> &'static str {
@@ -30,29 +16,42 @@ impl DeclarationType {
     }
 }
 
+#[derive(Clone, Copy, PartialEq, PartialOrd, Eq, Ord, Debug, Hash)]
+pub enum DeclarationType {
+    Struct,
+    Enum,
+    Union,
+}
+
+#[derive(Default)]
+pub struct DeclarationTypeResolver {
+    types: HashMap<Path, Option<DeclarationType>>,
+}
+
 impl DeclarationTypeResolver {
+    fn insert(&mut self, path: &Path, ty: Option<DeclarationType>) {
+        if let Entry::Vacant(vacant_entry) = self.types.entry(path.clone()) {
+            vacant_entry.insert(ty);
+        }
+    }
+
     pub fn add_enum(&mut self, path: &Path) {
-        self.enums.insert(path.clone());
+        self.insert(path, Some(DeclarationType::Enum));
     }
 
     pub fn add_struct(&mut self, path: &Path) {
-        self.structs.insert(path.clone());
+        self.insert(path, Some(DeclarationType::Struct));
     }
 
     pub fn add_union(&mut self, path: &Path) {
-        self.unions.insert(path.clone());
+        self.insert(path, Some(DeclarationType::Union));
+    }
+
+    pub fn add_none(&mut self, path: &Path) {
+        self.insert(path, None);
     }
 
     pub fn type_for(&self, path: &Path) -> Option<DeclarationType> {
-        // FIXME: don't look up by name, but by full path:
-        if self.structs.contains(path) {
-            Some(DeclarationType::Struct)
-        } else if self.enums.contains(path) {
-            Some(DeclarationType::Enum)
-        } else if self.unions.contains(path) {
-            Some(DeclarationType::Union)
-        } else {
-            None
-        }
+        *self.types.get(path)?
     }
 }
diff --git a/src/bindgen/ir/enumeration.rs b/src/bindgen/ir/enumeration.rs
index 7359e19..9d96b4c 100644
--- a/src/bindgen/ir/enumeration.rs
+++ b/src/bindgen/ir/enumeration.rs
@@ -476,12 +476,17 @@ impl Item for Enum {
     }
 
     fn collect_declaration_types(&self, resolver: &mut DeclarationTypeResolver) {
-        if self.tag.is_some() && self.repr.style == ReprStyle::C {
-            resolver.add_struct(&self.path);
-        } else if self.tag.is_some() && self.repr.style != ReprStyle::C {
-            resolver.add_union(&self.path);
+        if self.tag.is_some() {
+            if self.repr.style == ReprStyle::C {
+                resolver.add_struct(&self.path);
+            } else {
+                resolver.add_union(&self.path);
+            }
         } else if self.repr.style == ReprStyle::C {
             resolver.add_enum(&self.path);
+        } else {
+            // This is important to handle conflicting names with opaque items.
+            resolver.add_none(&self.path);
         }
     }
 
diff --git a/src/bindgen/ir/structure.rs b/src/bindgen/ir/structure.rs
index 8686758..05539eb 100644
--- a/src/bindgen/ir/structure.rs
+++ b/src/bindgen/ir/structure.rs
@@ -266,7 +266,9 @@ impl Item for Struct {
     }
 
     fn collect_declaration_types(&self, resolver: &mut DeclarationTypeResolver) {
-        if !self.is_transparent {
+        if self.is_transparent {
+            resolver.add_none(&self.path);
+        } else {
             resolver.add_struct(&self.path);
         }
     }
diff --git a/src/bindgen/ir/typedef.rs b/src/bindgen/ir/typedef.rs
index 9c779a4..61c071b 100644
--- a/src/bindgen/ir/typedef.rs
+++ b/src/bindgen/ir/typedef.rs
@@ -138,6 +138,10 @@ impl Item for Typedef {
         self.aliased.rename_for_config(config, &self.generic_params);
     }
 
+    fn collect_declaration_types(&self, resolver: &mut DeclarationTypeResolver) {
+        resolver.add_none(&self.path);
+    }
+
     fn resolve_declaration_types(&mut self, resolver: &DeclarationTypeResolver) {
         self.aliased.resolve_declaration_types(resolver);
     }
diff --git a/src/bindgen/library.rs b/src/bindgen/library.rs
index 855cca2..b1f9eb4 100644
--- a/src/bindgen/library.rs
+++ b/src/bindgen/library.rs
@@ -318,10 +318,6 @@ impl Library {
             x.collect_declaration_types(&mut resolver);
         });
 
-        self.opaque_items.for_all_items(|x| {
-            x.collect_declaration_types(&mut resolver);
-        });
-
         self.enums.for_all_items(|x| {
             x.collect_declaration_types(&mut resolver);
         });
@@ -330,6 +326,16 @@ impl Library {
             x.collect_declaration_types(&mut resolver);
         });
 
+        self.typedefs.for_all_items(|x| {
+            x.collect_declaration_types(&mut resolver);
+        });
+
+        // NOTE: Intentionally last, so that in case there's an opaque type
+        // which is conflicting with a non-opaque one, the later wins.
+        self.opaque_items.for_all_items(|x| {
+            x.collect_declaration_types(&mut resolver);
+        });
+
         self.enums
             .for_all_items_mut(|x| x.resolve_declaration_types(&resolver));
 
diff --git a/tests/expectations/decl_name_conflicting.both.c b/tests/expectations/decl_name_conflicting.both.c
new file mode 100644
index 0000000..486b31c
--- /dev/null
+++ b/tests/expectations/decl_name_conflicting.both.c
@@ -0,0 +1,16 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+enum BindingType {
+  Buffer = 0,
+  NotBuffer = 1,
+};
+typedef uint32_t BindingType;
+
+typedef struct BindGroupLayoutEntry {
+  BindingType ty;
+} BindGroupLayoutEntry;
+
+void root(struct BindGroupLayoutEntry entry);
diff --git a/tests/expectations/decl_name_conflicting.both.compat.c b/tests/expectations/decl_name_conflicting.both.compat.c
new file mode 100644
index 0000000..e8a8d49
--- /dev/null
+++ b/tests/expectations/decl_name_conflicting.both.compat.c
@@ -0,0 +1,30 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+enum BindingType
+#ifdef __cplusplus
+  : uint32_t
+#endif // __cplusplus
+ {
+  Buffer = 0,
+  NotBuffer = 1,
+};
+#ifndef __cplusplus
+typedef uint32_t BindingType;
+#endif // __cplusplus
+
+typedef struct BindGroupLayoutEntry {
+  BindingType ty;
+} BindGroupLayoutEntry;
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+void root(struct BindGroupLayoutEntry entry);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif // __cplusplus
diff --git a/tests/expectations/decl_name_conflicting.c b/tests/expectations/decl_name_conflicting.c
new file mode 100644
index 0000000..41a148e
--- /dev/null
+++ b/tests/expectations/decl_name_conflicting.c
@@ -0,0 +1,16 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+enum BindingType {
+  Buffer = 0,
+  NotBuffer = 1,
+};
+typedef uint32_t BindingType;
+
+typedef struct {
+  BindingType ty;
+} BindGroupLayoutEntry;
+
+void root(BindGroupLayoutEntry entry);
diff --git a/tests/expectations/decl_name_conflicting.compat.c b/tests/expectations/decl_name_conflicting.compat.c
new file mode 100644
index 0000000..a78700f
--- /dev/null
+++ b/tests/expectations/decl_name_conflicting.compat.c
@@ -0,0 +1,30 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+enum BindingType
+#ifdef __cplusplus
+  : uint32_t
+#endif // __cplusplus
+ {
+  Buffer = 0,
+  NotBuffer = 1,
+};
+#ifndef __cplusplus
+typedef uint32_t BindingType;
+#endif // __cplusplus
+
+typedef struct {
+  BindingType ty;
+} BindGroupLayoutEntry;
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+void root(BindGroupLayoutEntry entry);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif // __cplusplus
diff --git a/tests/expectations/decl_name_conflicting.cpp b/tests/expectations/decl_name_conflicting.cpp
new file mode 100644
index 0000000..74c2ae1
--- /dev/null
+++ b/tests/expectations/decl_name_conflicting.cpp
@@ -0,0 +1,20 @@
+#include <cstdarg>
+#include <cstdint>
+#include <cstdlib>
+#include <ostream>
+#include <new>
+
+enum class BindingType : uint32_t {
+  Buffer = 0,
+  NotBuffer = 1,
+};
+
+struct BindGroupLayoutEntry {
+  BindingType ty;
+};
+
+extern "C" {
+
+void root(BindGroupLayoutEntry entry);
+
+} // extern "C"
diff --git a/tests/expectations/decl_name_conflicting.pyx b/tests/expectations/decl_name_conflicting.pyx
new file mode 100644
index 0000000..d7dbc5e
--- /dev/null
+++ b/tests/expectations/decl_name_conflicting.pyx
@@ -0,0 +1,17 @@
+from libc.stdint cimport int8_t, int16_t, int32_t, int64_t, intptr_t
+from libc.stdint cimport uint8_t, uint16_t, uint32_t, uint64_t, uintptr_t
+cdef extern from *:
+  ctypedef bint bool
+  ctypedef struct va_list
+
+cdef extern from *:
+
+  cdef enum:
+    Buffer # = 0,
+    NotBuffer # = 1,
+  ctypedef uint32_t BindingType;
+
+  ctypedef struct BindGroupLayoutEntry:
+    BindingType ty;
+
+  void root(BindGroupLayoutEntry entry);
diff --git a/tests/expectations/decl_name_conflicting.tag.c b/tests/expectations/decl_name_conflicting.tag.c
new file mode 100644
index 0000000..7504e4a
--- /dev/null
+++ b/tests/expectations/decl_name_conflicting.tag.c
@@ -0,0 +1,16 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+enum BindingType {
+  Buffer = 0,
+  NotBuffer = 1,
+};
+typedef uint32_t BindingType;
+
+struct BindGroupLayoutEntry {
+  BindingType ty;
+};
+
+void root(struct BindGroupLayoutEntry entry);
diff --git a/tests/expectations/decl_name_conflicting.tag.compat.c b/tests/expectations/decl_name_conflicting.tag.compat.c
new file mode 100644
index 0000000..6011756
--- /dev/null
+++ b/tests/expectations/decl_name_conflicting.tag.compat.c
@@ -0,0 +1,30 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+enum BindingType
+#ifdef __cplusplus
+  : uint32_t
+#endif // __cplusplus
+ {
+  Buffer = 0,
+  NotBuffer = 1,
+};
+#ifndef __cplusplus
+typedef uint32_t BindingType;
+#endif // __cplusplus
+
+struct BindGroupLayoutEntry {
+  BindingType ty;
+};
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+void root(struct BindGroupLayoutEntry entry);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif // __cplusplus
diff --git a/tests/expectations/decl_name_conflicting.tag.pyx b/tests/expectations/decl_name_conflicting.tag.pyx
new file mode 100644
index 0000000..82ebc2f
--- /dev/null
+++ b/tests/expectations/decl_name_conflicting.tag.pyx
@@ -0,0 +1,17 @@
+from libc.stdint cimport int8_t, int16_t, int32_t, int64_t, intptr_t
+from libc.stdint cimport uint8_t, uint16_t, uint32_t, uint64_t, uintptr_t
+cdef extern from *:
+  ctypedef bint bool
+  ctypedef struct va_list
+
+cdef extern from *:
+
+  cdef enum:
+    Buffer # = 0,
+    NotBuffer # = 1,
+  ctypedef uint32_t BindingType;
+
+  cdef struct BindGroupLayoutEntry:
+    BindingType ty;
+
+  void root(BindGroupLayoutEntry entry);
diff --git a/tests/rust/decl_name_conflicting.rs b/tests/rust/decl_name_conflicting.rs
new file mode 100644
index 0000000..39e9658
--- /dev/null
+++ b/tests/rust/decl_name_conflicting.rs
@@ -0,0 +1,14 @@
+mod uhoh {
+    enum BindingType { Buffer, NotBuffer }
+}
+
+#[repr(u32)]
+pub enum BindingType { Buffer = 0, NotBuffer = 1 }
+
+#[repr(C)]
+pub struct BindGroupLayoutEntry {
+    pub ty: BindingType, // This is the repr(u32) enum
+}
+
+#[no_mangle]
+pub extern "C" fn root(entry: BindGroupLayoutEntry) {}