docs/markdown/Release-notes-for-1.9.0.md - meson - Git at Google

 ---
 title: Release 1.9.0
 short-description: Release notes for 1.9.0
 ...

 # New features

 Meson 1.9.0 was released on 24 August 2025
 ## Array `.flatten()` method

 Arrays now have a `.flatten()` method, which turns nested arrays into a single
 flat array. This provides the same effect that Meson often does to arrays
 internally, such as when passed to most function arguments.

 ## `clang-tidy`'s auto-generated targets correctly select source files

 In previous versions, the target would run `clang-tidy` on _every_ C-like source files (.c, .h, .cpp, .hpp). It did not work correctly because some files, especially headers, are not intended to be consumed as is.

 It will now run only on source files participating in targets.

 ## Added Qualcomm's embedded linker, eld

 Qualcomm recently open-sourced their embedded linker.
 https://github.com/qualcomm/eld

 Meson users can now use this linker.

 ## Added suffix function to the FS module

 The basename and stem were already available. For completeness, expose also the
 suffix.

 ## Support response files for custom targets

 When using the Ninja backend, Meson can now pass arguments to supported tools
 through response files.

 In this release it's enabled only for the Gnome module, fixing calling
 `gnome.mkenums()` with a large set of files on Windows (requires
 Glib 2.59 or higher).

 ## meson format now has a --source-file-path argument when reading from stdin

 This argument is mandatory to mix stdin reading with the use of editor config.
 It allows to know where to look for the .editorconfig, and to use the right
 section of .editorconfig based on the parsed file name.

 ## Added license keyword to pkgconfig.generate

 When specified, it will add a `License:` attribute to the generated .pc file.

 ## pkgconfig.generate supports internal dependencies in `requires`

 Internal dependencies can now be specified to `requires` if
 pkgconfig.generate was called on the underlying library.

 ## New experimental option `rust_dynamic_std`

 A new option `rust_dynamic_std` can be used to link Rust programs so
 that they use a dynamic library for the Rust `libstd`.

 Right now, `staticlib` crates cannot be produced if `rust_dynamic_std` is
 true, but this may change in the future.

 ## Rust and non-Rust sources in the same target

 Meson now supports creating a single target with Rust and non Rust
 sources mixed together.  In this case, if specified, `link_language`
 must be set to `rust`.

 ## Explicitly setting Swift module name is now supported

 It is now possible to set the Swift module name for a target via the
 *swift_module_name* target kwarg, overriding the default inferred from the
 target name.

 ```meson
 lib = library('foo', 'foo.swift', swift_module_name: 'Foo')
 ```

 ## Top-level statement handling in Swift libraries

 The Swift compiler normally treats modules with a single source
 file (and files named main.swift) to run top-level code at program
 start. This emits a main symbol which is usually undesirable in a
 library target. Meson now automatically passes the *-parse-as-library*
 flag to the Swift compiler in case of single-file library targets to
 disable this behavior unless the source file is called main.swift.

 ## Swift compiler receives select C family compiler options

 Meson now passes select few C family (C/C++/Obj-C/Obj-C++) compiler
 options to the Swift compiler, notably *-std=*, in order to improve
 the compatibility of C code as interpreted by the C compiler and the
 Swift compiler.

 NB: This does not include any of the options set in the target's
 c_flags.

 ## Swift/C++ interoperability is now supported

 It is now possible to create Swift executables that can link to C++ or
 Objective-C++ libraries. To enable this feature, set the target kwarg
 _swift\_interoperability\_mode_ to 'cpp'.

 To import C++ code, specify a bridging header in the Swift target's
 sources, or use another way such as adding a directory containing a
 Clang module map to its include path.

 Note: Enabling C++ interoperability in a library target is a breaking
 change. Swift libraries that enable it need their consumers to enable
 it as well, as per [the Swift documentation][1].

 Swift 5.9 is required to use this feature. Xcode 15 is required if the
 Xcode backend is used.

 ```meson
 lib = static_library('mylib', 'mylib.cpp')
 exe = executable('prog', 'main.swift', 'mylib.h', link_with: lib, swift_interoperability_mode: 'cpp')
 ```

 [1]: https://www.swift.org/documentation/cxx-interop/project-build-setup/#vending-packages-that-enable-c-interoperability

 ## Support for MASM in Visual Studio backends

 Previously, assembling `.masm` files with Microsoft's Macro Assembler is only
 available on the Ninja backend. This now also works on Visual Studio backends.

 Note that building ARM64EC code using `ml64.exe` is currently unimplemented in
 both of the backends. If you need mixing x64 and Arm64 in your project, please
 file an issue on GitHub.

 ## Limited support for WrapDB v1

 WrapDB v1 has been discontinued for several years, Meson will now print a
 deprecation warning if a v1 URL is still being used. Wraps can be updated to
 latest version using `meson wrap update` command.
	---
	title: Release 1.9.0
	short-description: Release notes for 1.9.0
	...

	# New features

	Meson 1.9.0 was released on 24 August 2025
	## Array `.flatten()` method

	Arrays now have a `.flatten()` method, which turns nested arrays into a single
	flat array. This provides the same effect that Meson often does to arrays
	internally, such as when passed to most function arguments.

	## `clang-tidy`'s auto-generated targets correctly select source files

	In previous versions, the target would run `clang-tidy` on _every_ C-like source files (.c, .h, .cpp, .hpp). It did not work correctly because some files, especially headers, are not intended to be consumed as is.

	It will now run only on source files participating in targets.

	## Added Qualcomm's embedded linker, eld

	Qualcomm recently open-sourced their embedded linker.
	https://github.com/qualcomm/eld

	Meson users can now use this linker.

	## Added suffix function to the FS module

	The basename and stem were already available. For completeness, expose also the
	suffix.

	## Support response files for custom targets

	When using the Ninja backend, Meson can now pass arguments to supported tools
	through response files.

	In this release it's enabled only for the Gnome module, fixing calling
	`gnome.mkenums()` with a large set of files on Windows (requires
	Glib 2.59 or higher).

	## meson format now has a --source-file-path argument when reading from stdin

	This argument is mandatory to mix stdin reading with the use of editor config.
	It allows to know where to look for the .editorconfig, and to use the right
	section of .editorconfig based on the parsed file name.

	## Added license keyword to pkgconfig.generate

	When specified, it will add a `License:` attribute to the generated .pc file.

	## pkgconfig.generate supports internal dependencies in `requires`

	Internal dependencies can now be specified to `requires` if
	pkgconfig.generate was called on the underlying library.

	## New experimental option `rust_dynamic_std`

	A new option `rust_dynamic_std` can be used to link Rust programs so
	that they use a dynamic library for the Rust `libstd`.

	Right now, `staticlib` crates cannot be produced if `rust_dynamic_std` is
	true, but this may change in the future.

	## Rust and non-Rust sources in the same target

	Meson now supports creating a single target with Rust and non Rust
	sources mixed together. In this case, if specified, `link_language`
	must be set to `rust`.

	## Explicitly setting Swift module name is now supported

	It is now possible to set the Swift module name for a target via the
	swift_module_name target kwarg, overriding the default inferred from the
	target name.

	```meson
	lib = library('foo', 'foo.swift', swift_module_name: 'Foo')
	```

	## Top-level statement handling in Swift libraries

	The Swift compiler normally treats modules with a single source
	file (and files named main.swift) to run top-level code at program
	start. This emits a main symbol which is usually undesirable in a
	library target. Meson now automatically passes the -parse-as-library
	flag to the Swift compiler in case of single-file library targets to
	disable this behavior unless the source file is called main.swift.

	## Swift compiler receives select C family compiler options

	Meson now passes select few C family (C/C++/Obj-C/Obj-C++) compiler
	options to the Swift compiler, notably -std=, in order to improve
	the compatibility of C code as interpreted by the C compiler and the
	Swift compiler.

	NB: This does not include any of the options set in the target's
	c_flags.

	## Swift/C++ interoperability is now supported

	It is now possible to create Swift executables that can link to C++ or
	Objective-C++ libraries. To enable this feature, set the target kwarg
	_swift\_interoperability\_mode_ to 'cpp'.

	To import C++ code, specify a bridging header in the Swift target's
	sources, or use another way such as adding a directory containing a
	Clang module map to its include path.

	Note: Enabling C++ interoperability in a library target is a breaking
	change. Swift libraries that enable it need their consumers to enable
	it as well, as per [the Swift documentation][1].

	Swift 5.9 is required to use this feature. Xcode 15 is required if the
	Xcode backend is used.

	```meson
	lib = static_library('mylib', 'mylib.cpp')
	exe = executable('prog', 'main.swift', 'mylib.h', link_with: lib, swift_interoperability_mode: 'cpp')
	```

	[1]: https://www.swift.org/documentation/cxx-interop/project-build-setup/#vending-packages-that-enable-c-interoperability

	## Support for MASM in Visual Studio backends

	Previously, assembling `.masm` files with Microsoft's Macro Assembler is only
	available on the Ninja backend. This now also works on Visual Studio backends.

	Note that building ARM64EC code using `ml64.exe` is currently unimplemented in
	both of the backends. If you need mixing x64 and Arm64 in your project, please
	file an issue on GitHub.

	## Limited support for WrapDB v1

	WrapDB v1 has been discontinued for several years, Meson will now print a
	deprecation warning if a v1 URL is still being used. Wraps can be updated to
	latest version using `meson wrap update` command.