Consistent allocation failure handling (#3209)

.github/workflows/clippy.yml

@@ -133,8 +133,6 @@ jobs:
         run:  cargo clippy -p test_array
       - name: Clippy test_bcrypt
         run:  cargo clippy -p test_bcrypt
-      - name: Clippy test_bstr
-        run:  cargo clippy -p test_bstr
       - name: Clippy test_calling_convention
         run:  cargo clippy -p test_calling_convention
       - name: Clippy test_cfg_generic

.github/workflows/test.yml

@@ -159,8 +159,6 @@ jobs:
         run:  cargo test -p test_array --target ${{ matrix.target }} ${{ matrix.etc }}
       - name: Test test_bcrypt
         run:  cargo test -p test_bcrypt --target ${{ matrix.target }} ${{ matrix.etc }}
-      - name: Test test_bstr
-        run:  cargo test -p test_bstr --target ${{ matrix.target }} ${{ matrix.etc }}
       - name: Test test_calling_convention
         run:  cargo test -p test_calling_convention --target ${{ matrix.target }} ${{ matrix.etc }}
       - name: Test test_cfg_generic
@@ -255,10 +253,10 @@ jobs:
         run:  cargo test -p test_standalone --target ${{ matrix.target }} ${{ matrix.etc }}
       - name: Test test_string_param
         run:  cargo test -p test_string_param --target ${{ matrix.target }} ${{ matrix.etc }}
-      - name: Clean
-        run:  cargo clean
       - name: Test test_strings
         run:  cargo test -p test_strings --target ${{ matrix.target }} ${{ matrix.etc }}
+      - name: Clean
+        run:  cargo clean
       - name: Test test_structs
         run:  cargo test -p test_structs --target ${{ matrix.target }} ${{ matrix.etc }}
       - name: Test test_sys

crates/libs/core/src/imp/com_bindings.rs

@@ -43,7 +43,6 @@ pub const CO_E_NOTINITIALIZED: windows_core::HRESULT = windows_core::HRESULT(0x8
 pub const E_BOUNDS: windows_core::HRESULT = windows_core::HRESULT(0x8000000B_u32 as _);
 pub const E_INVALIDARG: windows_core::HRESULT = windows_core::HRESULT(0x80070057_u32 as _);
 pub const E_NOINTERFACE: windows_core::HRESULT = windows_core::HRESULT(0x80004002_u32 as _);
-pub const E_OUTOFMEMORY: windows_core::HRESULT = windows_core::HRESULT(0x8007000E_u32 as _);
 pub const E_POINTER: windows_core::HRESULT = windows_core::HRESULT(0x80004003_u32 as _);
 windows_core::imp::define_interface!(
     IAgileObject,

crates/libs/registry/src/key.rs

@@ -175,7 +175,7 @@ impl Key {
             return Err(invalid_data());
         }
 
-        let mut value = HStringBuilder::new(len / 2)?;
+        let mut value = HStringBuilder::new(len / 2);
         unsafe { self.raw_get_bytes(name.as_raw(), value.as_bytes_mut())? };
         value.trim_end();
         Ok(value.into())

crates/libs/registry/src/value.rs

@@ -111,7 +111,7 @@ impl TryFrom<Value> for HSTRING {
     type Error = Error;
     fn try_from(from: Value) -> Result<Self> {
         match from.ty {
-            Type::String | Type::ExpandString => Ok(Self::from_wide(trim(from.data.as_wide()))?),
+            Type::String | Type::ExpandString => Ok(Self::from_wide(trim(from.data.as_wide()))),
             _ => Err(invalid_data()),
         }
     }

crates/libs/strings/Cargo.toml

@@ -21,11 +21,6 @@ targets = []
 version = "0.52.6"
 path = "../targets"
 
-[dependencies.windows-result]
-version = "0.2.0"
-path = "../result"
-default-features = false
-
 [features]
 default = ["std"]
 std = []

crates/libs/strings/readme.md

@@ -21,16 +21,14 @@ use windows_strings::*;
 const A: PCSTR = s!("ansi");
 const W: PCWSTR = w!("wide");
 
-fn main() -> Result<()> {
+fn main() {
     let b = BSTR::from("bstr");
     let h = HSTRING::from("hstring");
 
     assert_eq!(b, "bstr");
     assert_eq!(h, "hstring");
 
-    assert_eq!(unsafe { A.to_string()? }, "ansi");
-    assert_eq!(unsafe { W.to_string()? }, "wide");
-
-    Ok(())
+    assert_eq!(unsafe { A.to_string().unwrap() }, "ansi");
+    assert_eq!(unsafe { W.to_string().unwrap() }, "wide");
 }
 ```

crates/libs/strings/src/bindings.rs

@@ -13,8 +13,6 @@ windows_targets::link!("oleaut32.dll" "system" fn SysFreeString(bstrstring : BST
 windows_targets::link!("oleaut32.dll" "system" fn SysStringLen(pbstr : BSTR) -> u32);
 pub type BOOL = i32;
 pub type BSTR = *const u16;
-pub const E_OUTOFMEMORY: HRESULT = 0x8007000E_u32 as _;
 pub type HANDLE = *mut core::ffi::c_void;
 pub type HEAP_FLAGS = u32;
-pub type HRESULT = i32;
 pub type PCWSTR = *const u16;

crates/libs/strings/src/bstr.rs

@@ -43,23 +43,23 @@ impl BSTR {
     }
 
     /// Create a `BSTR` from a slice of 16 bit characters (wchars).
-    pub fn from_wide(value: &[u16]) -> Result<Self> {
+    pub fn from_wide(value: &[u16]) -> Self {
         if value.is_empty() {
-            return Ok(Self::new());
+            return Self::new();
         }
 
         let result = unsafe {
             Self(bindings::SysAllocStringLen(
                 value.as_ptr(),
-                value.len().try_into()?,
+                value.len().try_into().unwrap(),
             ))
         };
 
         if result.is_empty() {
-            Err(Error::from_hresult(HRESULT(bindings::E_OUTOFMEMORY)))
-        } else {
-            Ok(result)
+            panic!("allocation failed");
         }
+
+        result
     }
 
     /// # Safety
@@ -77,14 +77,14 @@ impl BSTR {
 
 impl Clone for BSTR {
     fn clone(&self) -> Self {
-        Self::from_wide(self.as_wide()).unwrap()
+        Self::from_wide(self.as_wide())
     }
 }
 
 impl From<&str> for BSTR {
     fn from(value: &str) -> Self {
         let value: alloc::vec::Vec<u16> = value.encode_utf16().collect();
-        Self::from_wide(&value).unwrap()
+        Self::from_wide(&value)
     }
 }
 

crates/libs/strings/src/hstring.rs

@@ -44,7 +44,7 @@ impl HSTRING {
     }
 
     /// Create a `HSTRING` from a slice of 16 bit characters (wchars).
-    pub fn from_wide(value: &[u16]) -> Result<Self> {
+    pub fn from_wide(value: &[u16]) -> Self {
         unsafe { Self::from_wide_iter(value.iter().copied(), value.len()) }
     }
 
@@ -61,12 +61,12 @@ impl HSTRING {
 
     /// # Safety
     /// len must not be less than the number of items in the iterator.
-    unsafe fn from_wide_iter<I: Iterator<Item = u16>>(iter: I, len: usize) -> Result<Self> {
+    unsafe fn from_wide_iter<I: Iterator<Item = u16>>(iter: I, len: usize) -> Self {
         if len == 0 {
-            return Ok(Self::new());
+            return Self::new();
         }
 
-        let ptr = HStringHeader::alloc(len.try_into()?)?;
+        let ptr = HStringHeader::alloc(len.try_into().unwrap());
 
         // Place each utf-16 character into the buffer and
         // increase len as we go along.
@@ -79,7 +79,7 @@ impl HSTRING {
 
         // Write a 0 byte to the end of the buffer.
         (*ptr).data.offset((*ptr).len as isize).write(0);
-        Ok(Self(ptr))
+        Self(ptr)
     }
 
     fn as_header(&self) -> Option<&HStringHeader> {
@@ -96,7 +96,7 @@ impl Default for HSTRING {
 impl Clone for HSTRING {
     fn clone(&self) -> Self {
         if let Some(header) = self.as_header() {
-            Self(header.duplicate().unwrap())
+            Self(header.duplicate())
         } else {
             Self::new()
         }
@@ -138,7 +138,7 @@ impl core::fmt::Debug for HSTRING {
 
 impl From<&str> for HSTRING {
     fn from(value: &str) -> Self {
-        unsafe { Self::from_wide_iter(value.encode_utf16(), value.len()).unwrap() }
+        unsafe { Self::from_wide_iter(value.encode_utf16(), value.len()) }
     }
 }
 
@@ -169,7 +169,6 @@ impl From<&std::ffi::OsStr> for HSTRING {
                 std::os::windows::ffi::OsStrExt::encode_wide(value),
                 value.len(),
             )
-            .unwrap()
         }
     }
 }

crates/libs/strings/src/hstring_builder.rs

@@ -8,14 +8,14 @@ pub struct HStringBuilder(*mut HStringHeader);
 
 impl HStringBuilder {
     /// Creates a preallocated `HSTRING` value.
-    pub fn new(len: usize) -> Result<Self> {
-        let header = HStringHeader::alloc(len.try_into()?)?;
+    pub fn new(len: usize) -> Self {
+        let header = HStringHeader::alloc(len.try_into().unwrap());
 
         if len > 0 {
             unsafe { core::ptr::write_bytes((*header).data, 0, len) };
         }
 
-        Ok(Self(header))
+        Self(header)
     }
 
     /// Shortens the string by removing any trailing 0 characters.

crates/libs/strings/src/hstring_header.rs

@@ -14,9 +14,9 @@ pub struct HStringHeader {
 }
 
 impl HStringHeader {
-    pub fn alloc(len: u32) -> Result<*mut Self> {
+    pub fn alloc(len: u32) -> *mut Self {
         if len == 0 {
-            return Ok(core::ptr::null_mut());
+            return core::ptr::null_mut();
         }
 
         // Allocate enough space for header and two bytes per character.
@@ -27,7 +27,7 @@ impl HStringHeader {
             unsafe { bindings::HeapAlloc(bindings::GetProcessHeap(), 0, bytes) } as *mut Self;
 
         if header.is_null() {
-            return Err(Error::from_hresult(HRESULT(bindings::E_OUTOFMEMORY)));
+            panic!("allocation failed");
         }
 
         unsafe {
@@ -38,7 +38,7 @@ impl HStringHeader {
             (*header).data = &mut (*header).buffer_start;
         }
 
-        Ok(header)
+        header
     }
 
     pub unsafe fn free(header: *mut Self) {
@@ -49,20 +49,20 @@ impl HStringHeader {
         bindings::HeapFree(bindings::GetProcessHeap(), 0, header as *mut _);
     }
 
-    pub fn duplicate(&self) -> Result<*mut Self> {
+    pub fn duplicate(&self) -> *mut Self {
         if self.flags & HSTRING_REFERENCE_FLAG == 0 {
             // If this is not a "fast pass" string then simply increment the reference count.
             self.count.add_ref();
-            Ok(self as *const Self as *mut Self)
+            self as *const Self as *mut Self
         } else {
             // Otherwise, allocate a new string and copy the value into the new string.
-            let copy = Self::alloc(self.len)?;
+            let copy = Self::alloc(self.len);
             // SAFETY: since we are duplicating the string it is safe to copy all data from self to the initialized `copy`.
             // We copy `len + 1` characters since `len` does not account for the terminating null character.
             unsafe {
                 core::ptr::copy_nonoverlapping(self.data, (*copy).data, self.len as usize + 1);
             }
-            Ok(copy)
+            copy
         }
     }
 }

crates/libs/strings/src/lib.rs

@@ -10,9 +10,6 @@
 extern crate alloc;
 use alloc::string::String;
 
-pub use windows_result::Result;
-use windows_result::*;
-
 mod bstr;
 pub use bstr::*;
 

crates/libs/strings/src/pcwstr.rs

@@ -70,7 +70,7 @@ impl PCWSTR {
     /// # Safety
     ///
     /// See the safety information for `PCWSTR::as_wide`.
-    pub unsafe fn to_hstring(&self) -> Result<HSTRING> {
+    pub unsafe fn to_hstring(&self) -> HSTRING {
         HSTRING::from_wide(self.as_wide())
     }
 

crates/libs/strings/src/pwstr.rs

@@ -67,7 +67,7 @@ impl PWSTR {
     /// # Safety
     ///
     /// See the safety information for `PWSTR::as_wide`.
-    pub unsafe fn to_hstring(&self) -> Result<HSTRING> {
+    pub unsafe fn to_hstring(&self) -> HSTRING {
         HSTRING::from_wide(self.as_wide())
     }
 

crates/tests/bstr/Cargo.toml

@@ -1,15 +0,0 @@
-[package]
-name = "test_bstr"
-version = "0.0.0"
-edition = "2021"
-publish = false
-
-[lib]
-doc = false
-doctest = false
-
-[dependencies.windows]
-path = "../../libs/windows"
-features = [
-    "Win32_Foundation",
-]

crates/tests/bstr/src/lib.rs

@@ -1 +0,0 @@
-

crates/tests/bstr/tests/bstr.rs

@@ -1,62 +0,0 @@
-use windows::core::*;
-use windows::Win32::Foundation::*;
-
-#[test]
-fn test() {
-    let b: BSTR = "hello".into();
-    assert_eq!(b, "hello");
-}
-
-#[test]
-fn clone() {
-    let a: BSTR = "hello".into();
-    assert!(!a.is_empty());
-    assert!(a.len() == 5);
-    let b = a.clone();
-    assert_eq!(a, "hello");
-    assert_eq!(b, "hello");
-    assert_eq!("hello", a);
-
-    let a = BSTR::default();
-    assert!(a.is_empty());
-    assert!(a.len() == 0);
-    let b = a.clone();
-    assert_eq!(a, "");
-    assert_eq!(b, "");
-
-    let a = BSTR::new();
-    assert!(a.is_empty());
-    assert!(a.len() == 0);
-    assert_eq!(a.len(), 0);
-    assert_eq!(a.as_wide().len(), 0);
-
-    let wide = &[0x68, 0x65, 0x6c, 0x6c, 0x6f];
-    let a = BSTR::from_wide(wide).unwrap();
-    assert!(!a.is_empty());
-    assert!(a.len() == 5);
-    assert_eq!(a.as_wide().len(), 5);
-    assert_eq!(a.as_wide(), wide);
-    assert_eq!(a, "hello");
-
-    let a: BSTR = "".into();
-    assert!(a.is_empty());
-    assert!(a.len() == 0);
-
-    let a: BSTR = unsafe { SysAllocStringLen(None) };
-    assert!(a.is_empty());
-    assert!(a.len() == 0);
-
-    let a = BSTR::from("a");
-    assert_eq!(a, String::from("a"));
-    assert_eq!(String::from("a"), a);
-}
-
-#[test]
-fn interop() -> Result<()> {
-    unsafe {
-        let b: BSTR = "hello".into();
-        SysAddRefString(&b)?;
-        SysFreeString(&b);
-        Ok(())
-    }
-}

crates/tests/core/tests/hstring.rs

@@ -1,311 +0,0 @@
-use windows::core::*;
-
-#[test]
-fn hstring_works() {
-    assert_eq!(std::mem::size_of::<HSTRING>(), std::mem::size_of::<usize>());
-    let empty = HSTRING::new();
-    assert!(empty.is_empty());
-    assert!(empty.is_empty());
-
-    let hello = HSTRING::from("Hello");
-    assert!(!hello.is_empty());
-    assert!(hello.len() == 5);
-
-    let rust = hello.to_string();
-    assert!(rust == "Hello");
-    assert!(rust.len() == 5);
-
-    let hello2 = hello.clone();
-    assert!(!hello2.is_empty());
-    assert!(hello2.len() == 5);
-
-    assert!(HSTRING::from("Hello") == HSTRING::from("Hello"));
-    assert!(HSTRING::from("Hello") != HSTRING::from("World"));
-
-    assert!(HSTRING::from("Hello") == "Hello");
-    assert!(HSTRING::from("Hello") != "Hello ");
-    assert!(HSTRING::from("Hello") != "Hell");
-    assert!(HSTRING::from("Hello") != "World");
-
-    assert!(HSTRING::from("Hello").to_string() == String::from("Hello"));
-}
-
-#[test]
-fn display_format() {
-    let value = HSTRING::from("Hello world");
-    assert!(format!("{}", value) == "Hello world");
-}
-
-#[test]
-fn display_invalid_format() {
-    let s = HSTRING::from_wide(&[
-        0xD834, 0xDD1E, 0x006d, 0x0075, 0x0073, 0xDD1E, 0x0069, 0x0063, 0xD834,
-    ])
-    .unwrap();
-    let d = format!("{}", s);
-    assert_eq!(d, "𝄞mus<EFBFBD>ic<EFBFBD>");
-}
-
-#[test]
-fn debug_format() {
-    let value = HSTRING::from("Hello world");
-    assert!(format!("{:?}", value) == r#""Hello world""#);
-}
-
-#[test]
-fn from_empty_string() {
-    let h = HSTRING::from("");
-    assert!(format!("{}", h).is_empty());
-}
-
-#[test]
-fn from_os_string_string() {
-    let wide_data = &[0xD834, 0xDD1E, 0x006d, 0x0075, 0xD800, 0x0069, 0x0063];
-    use std::os::windows::prelude::OsStringExt;
-    let o = std::ffi::OsString::from_wide(wide_data);
-    let h = HSTRING::from(o);
-    let d = HSTRING::from_wide(wide_data).unwrap();
-    assert_eq!(h, d);
-}
-
-#[test]
-fn from_os_str_string() {
-    let wide_data = &[0xD834, 0xDD1E, 0x006d, 0x0075, 0xD800, 0x0069, 0x0063];
-    use std::os::windows::prelude::OsStringExt;
-    let o = std::ffi::OsString::from_wide(wide_data);
-    let o = o.as_os_str();
-    let h = HSTRING::from(o);
-    let d = HSTRING::from_wide(wide_data).unwrap();
-    assert_eq!(h, d);
-}
-
-#[test]
-fn from_path() {
-    let p = std::path::Path::new("/foo/bar");
-    let h = HSTRING::from(p);
-    assert_eq!(h, "/foo/bar");
-}
-
-#[test]
-fn hstring_to_string() {
-    let h = HSTRING::from("test");
-    let s = String::try_from(h).unwrap();
-    assert!(s == "test");
-}
-
-#[test]
-fn hstring_to_string_err() {
-    // 𝄞mu<invalid>ic
-    let wide_data = &[0xD834, 0xDD1E, 0x006d, 0x0075, 0xD800, 0x0069, 0x0063];
-    let h = HSTRING::from_wide(wide_data).unwrap();
-    let err = String::try_from(h);
-    assert!(err.is_err());
-}
-
-#[test]
-fn hstring_to_string_lossy() {
-    // 𝄞mu<invalid>ic
-    let wide_data = &[0xD834, 0xDD1E, 0x006d, 0x0075, 0xD800, 0x0069, 0x0063];
-    let h = HSTRING::from_wide(wide_data).unwrap();
-    let s = h.to_string_lossy();
-    assert_eq!(s, "𝄞mu<EFBFBD>ic");
-}
-
-#[test]
-fn hstring_to_os_string() {
-    // 𝄞mu<invalid>ic
-    let wide_data = &[0xD834, 0xDD1E, 0x006d, 0x0075, 0xD800, 0x0069, 0x0063];
-    let h = HSTRING::from_wide(wide_data).unwrap();
-    let s = h.to_os_string();
-    use std::os::windows::prelude::OsStringExt;
-    assert_eq!(s, std::ffi::OsString::from_wide(wide_data));
-}
-
-#[test]
-fn hstring_hashing_equal_strings() {
-    // Checks if two strings of identical contents have the same hash
-    use std::hash::{DefaultHasher, Hash, Hasher};
-
-    let hstring_1 = HSTRING::from("Hello World");
-    let hstring_2 = HSTRING::from("Hello World");
-
-    assert_eq!(hstring_1, hstring_2);
-
-    let mut hasher_1 = DefaultHasher::new();
-    let mut hasher_2 = DefaultHasher::new();
-
-    hstring_1.hash(&mut hasher_1);
-    hstring_2.hash(&mut hasher_2);
-
-    let h1_hash = hasher_1.finish();
-    let h2_hash = hasher_2.finish();
-
-    assert_eq!(h1_hash, h2_hash);
-}
-
-#[test]
-fn hstring_hashing_different_strings() {
-    // Checks if two strings of different contents have the same hash
-    use std::hash::{DefaultHasher, Hash, Hasher};
-
-    let hstring_1 = HSTRING::from("Hello World");
-    let hstring_2 = HSTRING::from("Hello World 2");
-
-    assert_ne!(hstring_1, hstring_2);
-
-    let mut hasher_1 = DefaultHasher::new();
-    let mut hasher_2 = DefaultHasher::new();
-
-    hstring_1.hash(&mut hasher_1);
-    hstring_2.hash(&mut hasher_2);
-
-    let h1_hash = hasher_1.finish();
-    let h2_hash = hasher_2.finish();
-
-    assert_ne!(h1_hash, h2_hash);
-}
-
-#[test]
-fn hstring_equality_combinations() {
-    let h = HSTRING::from("test");
-    let s = String::from("test");
-    let ss: &str = "test";
-
-    assert_eq!(h, s);
-    assert_eq!(&h, s);
-    assert_eq!(h, &s);
-    assert_eq!(&h, &s);
-
-    assert_eq!(s, h);
-    assert_eq!(s, &h);
-    assert_eq!(&s, h);
-    assert_eq!(&s, &h);
-
-    assert_eq!(h, *ss);
-    assert_eq!(&h, *ss);
-    assert_eq!(h, ss);
-    assert_eq!(&h, ss);
-
-    assert_eq!(*ss, h);
-    assert_eq!(*ss, &h);
-    assert_eq!(ss, h);
-    assert_eq!(ss, &h);
-}
-
-#[test]
-fn hstring_osstring_equality_combinations() {
-    let wide_data = &[0xD834, 0xDD1E, 0x006d, 0x0075, 0xD800, 0x0069, 0x0063];
-    let h = HSTRING::from_wide(wide_data).unwrap();
-    use std::os::windows::prelude::OsStringExt;
-    let s = std::ffi::OsString::from_wide(wide_data);
-    let ss = s.as_os_str();
-
-    assert_eq!(h, s);
-    assert_eq!(&h, s);
-    assert_eq!(h, &s);
-    assert_eq!(&h, &s);
-
-    assert_eq!(s, h);
-    assert_eq!(s, &h);
-    assert_eq!(&s, h);
-    assert_eq!(&s, &h);
-
-    assert_eq!(h, *ss);
-    assert_eq!(&h, *ss);
-    assert_eq!(h, ss);
-    assert_eq!(&h, ss);
-
-    assert_eq!(*ss, h);
-    assert_eq!(*ss, &h);
-    assert_eq!(ss, h);
-    assert_eq!(ss, &h);
-}
-
-#[test]
-fn hstring_compat() -> Result<()> {
-    unsafe {
-        use windows::Win32::System::WinRT::*;
-        let hey = HSTRING::from("Hey");
-        let world = HSTRING::from("World");
-        assert_eq!(WindowsCompareStringOrdinal(&hey, &world)?, -1);
-
-        let result = WindowsConcatString(&hey, &world)?;
-        assert_eq!(result, "HeyWorld");
-
-        let result = WindowsCreateString(Some(&hey.as_wide()))?;
-        assert_eq!(result, "Hey");
-
-        let result = WindowsDuplicateString(&hey)?;
-        assert_eq!(result, "Hey");
-
-        assert_eq!(WindowsGetStringLen(&hey), 3);
-        assert_eq!(WindowsGetStringLen(&world), 5);
-
-        assert_eq!(WindowsIsStringEmpty(&HSTRING::new()), true);
-        assert_eq!(WindowsIsStringEmpty(&HSTRING::default()), true);
-        assert_eq!(WindowsIsStringEmpty(&world), false);
-
-        let mut len = 0;
-        let buffer = WindowsGetStringRawBuffer(&world, Some(&mut len));
-        assert_eq!(len, 5);
-        // Adding +1 to the length of the slice to validate that it is null terminated.
-        assert_eq!(
-            std::slice::from_raw_parts(buffer.0, 6),
-            [87, 111, 114, 108, 100, 0]
-        );
-
-        // We need to drop to raw bindings to call the raw WindowsDeleteString function to avoid double-freeing the HSTRING,
-        // but this test is important as it ensures that the allocators match.
-        let hresult =
-            sys::WindowsDeleteString(std::mem::transmute_copy(&*std::mem::ManuallyDrop::new(hey)));
-        assert_eq!(hresult, 0);
-
-        // An HSTRING reference a.k.a. "fast pass" string is a kind of stack-based HSTRING used by C++ callers
-        // to avoid the heap allocation in some cases. It's not used in Rust since it assumes a wide character
-        // string literal, which is inconvenient to create in Rust. Here we again use raw bindings to make one
-        // and thereby excercise the windows::core::HSTRING support for HSTRING reference duplication.
-        let mut header: sys::HSTRING_HEADER = std::mem::zeroed();
-        let mut stack_hstring: sys::HSTRING = std::mem::zeroed();
-        let hresult = sys::WindowsCreateStringReference(
-            [87, 111, 114, 108, 100, 0].as_ptr(),
-            5,
-            &mut header,
-            &mut stack_hstring,
-        );
-        assert_eq!(hresult, 0);
-        assert_eq!(header.length, 5);
-        let stack_hstring: std::mem::ManuallyDrop<HSTRING> = std::mem::transmute(stack_hstring);
-        let duplicate: HSTRING = (*stack_hstring).clone();
-        assert_eq!(&duplicate, &*stack_hstring);
-        assert_eq!(duplicate, "World");
-
-        let mut len = 0;
-        let buffer = WindowsGetStringRawBuffer(&duplicate, Some(&mut len));
-        assert_eq!(len, 5);
-        // Adding +1 to the length of the slice to validate that it is null terminated.
-        assert_eq!(
-            std::slice::from_raw_parts(buffer.0, 6),
-            [87, 111, 114, 108, 100, 0]
-        );
-
-        Ok(())
-    }
-}
-
-mod sys {
-    windows_targets::link!("api-ms-win-core-winrt-string-l1-1-0.dll" "system" fn WindowsCreateStringReference(sourcestring: PCWSTR, length: u32, hstringheader: *mut HSTRING_HEADER, string: *mut HSTRING) -> HRESULT);
-    windows_targets::link!("api-ms-win-core-winrt-string-l1-1-0.dll" "system" fn WindowsDeleteString(string: HSTRING) -> HRESULT);
-
-    pub type HRESULT = i32;
-    pub type HSTRING = *mut core::ffi::c_void;
-    pub type PCWSTR = *const u16;
-
-    #[repr(C)]
-    pub struct HSTRING_HEADER {
-        pub flags: u32,
-        pub length: u32,
-        pub padding1: u32,
-        pub padding2: u32,
-        pub data: isize,
-    }
-}

crates/tests/strings/Cargo.toml

@@ -10,3 +10,16 @@ doctest = false
 
 [dependencies.windows-strings]
 path = "../../libs/strings"
+
+[dependencies.windows-targets]
+path = "../../libs/targets"
+
+[dependencies.windows]
+path = "../../libs/windows"
+features = [
+    "Win32_Foundation",
+    "Win32_System_WinRT",
+]
+
+[dev-dependencies]
+helpers = { package = "test_helpers", path = "../helpers" }

crates/tests/strings/tests/bstr.rs

@@ -1,9 +1,62 @@
+use windows::{core::Result, Win32::Foundation::*};
 use windows_strings::*;
 
 #[test]
-fn bstr() -> Result<()> {
-    let s = BSTR::from("hello");
-    assert_eq!(s.len(), 5);
-
-    Ok(())
+fn test() {
+    let b: BSTR = "hello".into();
+    assert_eq!(b, "hello");
+}
+
+#[test]
+fn clone() {
+    let a: BSTR = "hello".into();
+    assert!(!a.is_empty());
+    assert!(a.len() == 5);
+    let b = a.clone();
+    assert_eq!(a, "hello");
+    assert_eq!(b, "hello");
+    assert_eq!("hello", a);
+
+    let a = BSTR::default();
+    assert!(a.is_empty());
+    assert!(a.len() == 0);
+    let b = a.clone();
+    assert_eq!(a, "");
+    assert_eq!(b, "");
+
+    let a = BSTR::new();
+    assert!(a.is_empty());
+    assert!(a.len() == 0);
+    assert_eq!(a.len(), 0);
+    assert_eq!(a.as_wide().len(), 0);
+
+    let wide = &[0x68, 0x65, 0x6c, 0x6c, 0x6f];
+    let a = BSTR::from_wide(wide);
+    assert!(!a.is_empty());
+    assert!(a.len() == 5);
+    assert_eq!(a.as_wide().len(), 5);
+    assert_eq!(a.as_wide(), wide);
+    assert_eq!(a, "hello");
+
+    let a: BSTR = "".into();
+    assert!(a.is_empty());
+    assert!(a.len() == 0);
+
+    let a: BSTR = unsafe { SysAllocStringLen(None) };
+    assert!(a.is_empty());
+    assert!(a.len() == 0);
+
+    let a = BSTR::from("a");
+    assert_eq!(a, String::from("a"));
+    assert_eq!(String::from("a"), a);
+}
+
+#[test]
+fn interop() -> Result<()> {
+    unsafe {
+        let b: BSTR = "hello".into();
+        SysAddRefString(&b)?;
+        SysFreeString(&b);
+        Ok(())
+    }
 }

crates/tests/strings/tests/hstring.rs

@@ -1,56 +1,311 @@
+use windows::core::Result;
 use windows_strings::*;
 
 #[test]
-fn hstring() -> Result<()> {
-    let s = HSTRING::from("hello");
-    assert_eq!(s.len(), 5);
-    assert_eq!(s.as_wide().len(), 5);
+fn hstring_works() {
+    assert_eq!(std::mem::size_of::<HSTRING>(), std::mem::size_of::<usize>());
+    let empty = HSTRING::new();
+    assert!(empty.is_empty());
+    assert!(empty.is_empty());
 
-    Ok(())
+    let hello = HSTRING::from("Hello");
+    assert!(!hello.is_empty());
+    assert!(hello.len() == 5);
+
+    let rust = hello.to_string();
+    assert!(rust == "Hello");
+    assert!(rust.len() == 5);
+
+    let hello2 = hello.clone();
+    assert!(!hello2.is_empty());
+    assert!(hello2.len() == 5);
+
+    assert!(HSTRING::from("Hello") == HSTRING::from("Hello"));
+    assert!(HSTRING::from("Hello") != HSTRING::from("World"));
+
+    assert!(HSTRING::from("Hello") == "Hello");
+    assert!(HSTRING::from("Hello") != "Hello ");
+    assert!(HSTRING::from("Hello") != "Hell");
+    assert!(HSTRING::from("Hello") != "World");
+
+    assert!(HSTRING::from("Hello").to_string() == String::from("Hello"));
 }
 
 #[test]
-fn hstring_builder() -> Result<()> {
-    // Dropping a builder is fine.
-    _ = HStringBuilder::new(10)?;
+fn display_format() {
+    let value = HSTRING::from("Hello world");
+    assert!(format!("{}", value) == "Hello world");
+}
 
-    // A zero length builder is also fine.
-    let b = HStringBuilder::new(0)?;
-    let h: HSTRING = b.into();
-    assert!(h.is_empty());
+#[test]
+fn display_invalid_format() {
+    let s = HSTRING::from_wide(&[
+        0xD834, 0xDD1E, 0x006d, 0x0075, 0x0073, 0xDD1E, 0x0069, 0x0063, 0xD834,
+    ]);
+    let d = format!("{}", s);
+    assert_eq!(d, "𝄞mus<EFBFBD>ic<EFBFBD>");
+}
 
-    // Trimming a zero length builder is also fine.
-    let mut b = HStringBuilder::new(0)?;
-    b.trim_end();
-    let h: HSTRING = b.into();
-    assert!(h.is_empty());
+#[test]
+fn debug_format() {
+    let value = HSTRING::from("Hello world");
+    assert!(format!("{:?}", value) == r#""Hello world""#);
+}
 
-    // This depends on DerefMut.
-    const HELLO: [u16; 5] = [0x48, 0x65, 0x6C, 0x6C, 0x6F];
-    let mut b = HStringBuilder::new(5)?;
-    b.copy_from_slice(&HELLO);
-    let h: HSTRING = b.into();
-    assert_eq!(&h, "Hello");
+#[test]
+fn from_empty_string() {
+    let h = HSTRING::from("");
+    assert!(format!("{}", h).is_empty());
+}
 
-    // HSTRING can handle embedded nulls.
-    const HELLO00: [u16; 7] = [0x48, 0x65, 0x6C, 0x6C, 0x6F, 0x00, 0x00];
-    let mut b = HStringBuilder::new(7)?;
-    b.copy_from_slice(&HELLO00);
-    let h: HSTRING = b.into();
-    assert_eq!(h.len(), 7);
-    assert_eq!(h.as_wide(), HELLO00);
+#[test]
+fn from_os_string_string() {
+    let wide_data = &[0xD834, 0xDD1E, 0x006d, 0x0075, 0xD800, 0x0069, 0x0063];
+    use std::os::windows::prelude::OsStringExt;
+    let o = std::ffi::OsString::from_wide(wide_data);
+    let h = HSTRING::from(o);
+    let d = HSTRING::from_wide(wide_data);
+    assert_eq!(h, d);
+}
 
-    // But trim_end can avoid that.
-    let mut b = HStringBuilder::new(7)?;
-    b.copy_from_slice(&HELLO00);
-    b.trim_end();
-    let h: HSTRING = b.into();
-    assert_eq!(h.len(), 5);
-    assert_eq!(h.as_wide(), HELLO);
+#[test]
+fn from_os_str_string() {
+    let wide_data = &[0xD834, 0xDD1E, 0x006d, 0x0075, 0xD800, 0x0069, 0x0063];
+    use std::os::windows::prelude::OsStringExt;
+    let o = std::ffi::OsString::from_wide(wide_data);
+    let o = o.as_os_str();
+    let h = HSTRING::from(o);
+    let d = HSTRING::from_wide(wide_data);
+    assert_eq!(h, d);
+}
 
-    // HStringBuilder will initialize memory to zero.
-    let b = HStringBuilder::new(5)?;
-    assert_eq!(*b, [0, 0, 0, 0, 0]);
+#[test]
+fn from_path() {
+    let p = std::path::Path::new("/foo/bar");
+    let h = HSTRING::from(p);
+    assert_eq!(h, "/foo/bar");
+}
+
+#[test]
+fn hstring_to_string() {
+    let h = HSTRING::from("test");
+    let s = String::try_from(h).unwrap();
+    assert!(s == "test");
+}
+
+#[test]
+fn hstring_to_string_err() {
+    // 𝄞mu<invalid>ic
+    let wide_data = &[0xD834, 0xDD1E, 0x006d, 0x0075, 0xD800, 0x0069, 0x0063];
+    let h = HSTRING::from_wide(wide_data);
+    let err = String::try_from(h);
+    assert!(err.is_err());
+}
+
+#[test]
+fn hstring_to_string_lossy() {
+    // 𝄞mu<invalid>ic
+    let wide_data = &[0xD834, 0xDD1E, 0x006d, 0x0075, 0xD800, 0x0069, 0x0063];
+    let h = HSTRING::from_wide(wide_data);
+    let s = h.to_string_lossy();
+    assert_eq!(s, "𝄞mu<EFBFBD>ic");
+}
+
+#[test]
+fn hstring_to_os_string() {
+    // 𝄞mu<invalid>ic
+    let wide_data = &[0xD834, 0xDD1E, 0x006d, 0x0075, 0xD800, 0x0069, 0x0063];
+    let h = HSTRING::from_wide(wide_data);
+    let s = h.to_os_string();
+    use std::os::windows::prelude::OsStringExt;
+    assert_eq!(s, std::ffi::OsString::from_wide(wide_data));
+}
+
+#[test]
+fn hstring_hashing_equal_strings() {
+    // Checks if two strings of identical contents have the same hash
+    use std::hash::{DefaultHasher, Hash, Hasher};
+
+    let hstring_1 = HSTRING::from("Hello World");
+    let hstring_2 = HSTRING::from("Hello World");
+
+    assert_eq!(hstring_1, hstring_2);
+
+    let mut hasher_1 = DefaultHasher::new();
+    let mut hasher_2 = DefaultHasher::new();
+
+    hstring_1.hash(&mut hasher_1);
+    hstring_2.hash(&mut hasher_2);
+
+    let h1_hash = hasher_1.finish();
+    let h2_hash = hasher_2.finish();
+
+    assert_eq!(h1_hash, h2_hash);
+}
+
+#[test]
+fn hstring_hashing_different_strings() {
+    // Checks if two strings of different contents have the same hash
+    use std::hash::{DefaultHasher, Hash, Hasher};
+
+    let hstring_1 = HSTRING::from("Hello World");
+    let hstring_2 = HSTRING::from("Hello World 2");
+
+    assert_ne!(hstring_1, hstring_2);
+
+    let mut hasher_1 = DefaultHasher::new();
+    let mut hasher_2 = DefaultHasher::new();
+
+    hstring_1.hash(&mut hasher_1);
+    hstring_2.hash(&mut hasher_2);
+
+    let h1_hash = hasher_1.finish();
+    let h2_hash = hasher_2.finish();
+
+    assert_ne!(h1_hash, h2_hash);
+}
+
+#[test]
+fn hstring_equality_combinations() {
+    let h = HSTRING::from("test");
+    let s = String::from("test");
+    let ss: &str = "test";
+
+    assert_eq!(h, s);
+    assert_eq!(&h, s);
+    assert_eq!(h, &s);
+    assert_eq!(&h, &s);
+
+    assert_eq!(s, h);
+    assert_eq!(s, &h);
+    assert_eq!(&s, h);
+    assert_eq!(&s, &h);
+
+    assert_eq!(h, *ss);
+    assert_eq!(&h, *ss);
+    assert_eq!(h, ss);
+    assert_eq!(&h, ss);
+
+    assert_eq!(*ss, h);
+    assert_eq!(*ss, &h);
+    assert_eq!(ss, h);
+    assert_eq!(ss, &h);
+}
+
+#[test]
+fn hstring_osstring_equality_combinations() {
+    let wide_data = &[0xD834, 0xDD1E, 0x006d, 0x0075, 0xD800, 0x0069, 0x0063];
+    let h = HSTRING::from_wide(wide_data);
+    use std::os::windows::prelude::OsStringExt;
+    let s = std::ffi::OsString::from_wide(wide_data);
+    let ss = s.as_os_str();
+
+    assert_eq!(h, s);
+    assert_eq!(&h, s);
+    assert_eq!(h, &s);
+    assert_eq!(&h, &s);
+
+    assert_eq!(s, h);
+    assert_eq!(s, &h);
+    assert_eq!(&s, h);
+    assert_eq!(&s, &h);
+
+    assert_eq!(h, *ss);
+    assert_eq!(&h, *ss);
+    assert_eq!(h, ss);
+    assert_eq!(&h, ss);
+
+    assert_eq!(*ss, h);
+    assert_eq!(*ss, &h);
+    assert_eq!(ss, h);
+    assert_eq!(ss, &h);
+}
+
+#[test]
+fn hstring_compat() -> Result<()> {
+    unsafe {
+        use windows::Win32::System::WinRT::*;
+        let hey = HSTRING::from("Hey");
+        let world = HSTRING::from("World");
+        assert_eq!(WindowsCompareStringOrdinal(&hey, &world)?, -1);
+
+        let result = WindowsConcatString(&hey, &world)?;
+        assert_eq!(result, "HeyWorld");
+
+        let result = WindowsCreateString(Some(&hey.as_wide()))?;
+        assert_eq!(result, "Hey");
+
+        let result = WindowsDuplicateString(&hey)?;
+        assert_eq!(result, "Hey");
+
+        assert_eq!(WindowsGetStringLen(&hey), 3);
+        assert_eq!(WindowsGetStringLen(&world), 5);
+
+        assert_eq!(WindowsIsStringEmpty(&HSTRING::new()), true);
+        assert_eq!(WindowsIsStringEmpty(&HSTRING::default()), true);
+        assert_eq!(WindowsIsStringEmpty(&world), false);
+
+        let mut len = 0;
+        let buffer = WindowsGetStringRawBuffer(&world, Some(&mut len));
+        assert_eq!(len, 5);
+        // Adding +1 to the length of the slice to validate that it is null terminated.
+        assert_eq!(
+            std::slice::from_raw_parts(buffer.0, 6),
+            [87, 111, 114, 108, 100, 0]
+        );
+
+        // We need to drop to raw bindings to call the raw WindowsDeleteString function to avoid double-freeing the HSTRING,
+        // but this test is important as it ensures that the allocators match.
+        let hresult =
+            sys::WindowsDeleteString(std::mem::transmute_copy(&*std::mem::ManuallyDrop::new(hey)));
+        assert_eq!(hresult, 0);
+
+        // An HSTRING reference a.k.a. "fast pass" string is a kind of stack-based HSTRING used by C++ callers
+        // to avoid the heap allocation in some cases. It's not used in Rust since it assumes a wide character
+        // string literal, which is inconvenient to create in Rust. Here we again use raw bindings to make one
+        // and thereby excercise the windows::core::HSTRING support for HSTRING reference duplication.
+        let mut header: sys::HSTRING_HEADER = std::mem::zeroed();
+        let mut stack_hstring: sys::HSTRING = std::mem::zeroed();
+        let hresult = sys::WindowsCreateStringReference(
+            [87, 111, 114, 108, 100, 0].as_ptr(),
+            5,
+            &mut header,
+            &mut stack_hstring,
+        );
+        assert_eq!(hresult, 0);
+        assert_eq!(header.length, 5);
+        let stack_hstring: std::mem::ManuallyDrop<HSTRING> = std::mem::transmute(stack_hstring);
+        let duplicate: HSTRING = (*stack_hstring).clone();
+        assert_eq!(&duplicate, &*stack_hstring);
+        assert_eq!(duplicate, "World");
+
+        let mut len = 0;
+        let buffer = WindowsGetStringRawBuffer(&duplicate, Some(&mut len));
+        assert_eq!(len, 5);
+        // Adding +1 to the length of the slice to validate that it is null terminated.
+        assert_eq!(
+            std::slice::from_raw_parts(buffer.0, 6),
+            [87, 111, 114, 108, 100, 0]
+        );
 
         Ok(())
+    }
+}
+
+mod sys {
+    windows_targets::link!("api-ms-win-core-winrt-string-l1-1-0.dll" "system" fn WindowsCreateStringReference(sourcestring: PCWSTR, length: u32, hstringheader: *mut HSTRING_HEADER, string: *mut HSTRING) -> HRESULT);
+    windows_targets::link!("api-ms-win-core-winrt-string-l1-1-0.dll" "system" fn WindowsDeleteString(string: HSTRING) -> HRESULT);
+
+    pub type HRESULT = i32;
+    pub type HSTRING = *mut core::ffi::c_void;
+    pub type PCWSTR = *const u16;
+
+    #[repr(C)]
+    pub struct HSTRING_HEADER {
+        pub flags: u32,
+        pub length: u32,
+        pub padding1: u32,
+        pub padding2: u32,
+        pub data: isize,
+    }
 }

crates/tests/strings/tests/hstring_builder.rs

@@ -0,0 +1,52 @@
+use windows_strings::*;
+
+#[test]
+fn hstring() {
+    let s = HSTRING::from("hello");
+    assert_eq!(s.len(), 5);
+    assert_eq!(s.as_wide().len(), 5);
+}
+
+#[test]
+fn hstring_builder() {
+    // Dropping a builder is fine.
+    _ = HStringBuilder::new(10);
+
+    // A zero length builder is also fine.
+    let b = HStringBuilder::new(0);
+    let h: HSTRING = b.into();
+    assert!(h.is_empty());
+
+    // Trimming a zero length builder is also fine.
+    let mut b = HStringBuilder::new(0);
+    b.trim_end();
+    let h: HSTRING = b.into();
+    assert!(h.is_empty());
+
+    // This depends on DerefMut.
+    const HELLO: [u16; 5] = [0x48, 0x65, 0x6C, 0x6C, 0x6F];
+    let mut b = HStringBuilder::new(5);
+    b.copy_from_slice(&HELLO);
+    let h: HSTRING = b.into();
+    assert_eq!(&h, "Hello");
+
+    // HSTRING can handle embedded nulls.
+    const HELLO00: [u16; 7] = [0x48, 0x65, 0x6C, 0x6C, 0x6F, 0x00, 0x00];
+    let mut b = HStringBuilder::new(7);
+    b.copy_from_slice(&HELLO00);
+    let h: HSTRING = b.into();
+    assert_eq!(h.len(), 7);
+    assert_eq!(h.as_wide(), HELLO00);
+
+    // But trim_end can avoid that.
+    let mut b = HStringBuilder::new(7);
+    b.copy_from_slice(&HELLO00);
+    b.trim_end();
+    let h: HSTRING = b.into();
+    assert_eq!(h.len(), 5);
+    assert_eq!(h.as_wide(), HELLO);
+
+    // HStringBuilder will initialize memory to zero.
+    let b = HStringBuilder::new(5);
+    assert_eq!(*b, [0, 0, 0, 0, 0]);
+}

crates/tests/strings/tests/literals.rs

@@ -1,3 +1,4 @@
+use windows::core::Result;
 use windows_strings::*;
 
 #[test]

crates/tests/strings/tests/pcwstr.rs

@@ -19,7 +19,7 @@ fn test() -> Result<()> {
     );
 
     let p: PCWSTR = w!("world");
-    let s: HSTRING = unsafe { p.to_hstring()? };
+    let s: HSTRING = unsafe { p.to_hstring() };
     assert_eq!("world", s);
 
     Ok(())

crates/tests/strings/tests/pwstr.rs

@@ -19,7 +19,7 @@ fn test() -> Result<()> {
     );
 
     let p = PWSTR::from_raw(w!("world").as_ptr() as *mut _);
-    let s: HSTRING = unsafe { p.to_hstring()? };
+    let s: HSTRING = unsafe { p.to_hstring() };
     assert_eq!("world", s);
 
     Ok(())

crates/tools/bindings/src/core_com.txt

@@ -8,7 +8,6 @@
     Windows.Win32.Foundation.E_BOUNDS
     Windows.Win32.Foundation.E_INVALIDARG
     Windows.Win32.Foundation.E_NOINTERFACE
-    Windows.Win32.Foundation.E_OUTOFMEMORY
     Windows.Win32.Foundation.E_POINTER
     Windows.Win32.Foundation.JSCRIPT_E_CANTEXECUTE
     Windows.Win32.Foundation.RPC_E_DISCONNECTED

crates/tools/bindings/src/strings.txt

@@ -4,7 +4,6 @@
 --config flatten sys minimal no-bindgen-comment
 
 --filter
-    Windows.Win32.Foundation.E_OUTOFMEMORY
     Windows.Win32.Foundation.SysAllocStringLen
     Windows.Win32.Foundation.SysFreeString
     Windows.Win32.Foundation.SysStringLen