C3 0.8.2 A modest improvement

C3 0.8.2 is out. This release brings a batch of language ergonomics improvements — most notably reusable target templates for libraries and generic constdef — along with new reflection capabilities and a round of bug fixes. Compared to 0.8.1, this is a rather modest release, but anyway, here's what's new: Language changes & improvements¶ Reusable target configurations for libraries¶ Libraries can now expose a templates map in their manifest, and projects can pull one into a target with template: "library/template". Template properties load first and target-local settings override them, so libraries can ship sensible, shareable build configurations instead of asking every user to copy-paste setup. Reflection for generics¶ Foo::is_generic(...), Foo::generic_qname, and Foo::generic_args finally lets you inspect generic instantiations. alias Foo = List{int};

fn void main() { typeid t = List{String}::generic_args[0]; //String::typeid String name = Foo::generic_qname; // "std::collections::list::List" bool x = Foo::is_generic(List); // true bool y = int::is_generic(List); // false } Bitstruct properties¶ Bitstruct members gain bitoffset and bitsize properties: bitstruct Foo : uint { uint a : 0..1; bool b : 6; bool c : 10; int d : 14..20; }

fn void main() { int a = $reflect(Foo.a).bitsize; // 2 int b = $reflect(Foo.d).bitoffset; // 14 int c = $reflect(Foo.c).bitoffset; // 10 } New @param options: own, init and drop¶ It's now possible to annotate more than in/inout/out on parameters: own signifies that the function will in some way retain the variable beyond the scope of the function. drop means that the pointer and the data pointed to will be invalid when the function returns. init means that the data pointed to will be initialized by the function. This can be used by the compiler for static analysis and also documents the function or macro.

<* @param [own] f *> fn void foo(Foo* f) { some_global.foo = f; } Asm stack alignment¶ Before 0.8.2, all asm blocks would be stack aligned, which didn't match C behaviour. This is now fixed. Stack alignment is now opt-in by using @align: asm // Unaligned { syscall; }

asm @align // Stack aligned { syscall; } Windows improvements¶ The Windows subsystem can now be set directly. Windows can still use @winmain to implicitly set the Window subsystem, but all subsystems are now available, allowing for things like EFI applications. Standard library¶ Atomic.compare_exchange added. array::contains_slice and array::index_of_slice for substring-style searches over arrays. log::register_dynamic_category, for libraries to define their own logging categories dynamically. String.index_of and rindex_of now accept finding empty strings. Fixes¶ Stdlib fixes¶ Denormal (subnormal) results are now handled correctly by String.to_double() — very small magnitudes near the floating-point floor previously came out wrong. A float literal with an uppercase F suffix was incorrectly typed as a double instead of a float. JSON serialization now correctly handles Unicode and \v (#3353). IPv6 parsing: "a::b:c:d:e:f:0" is now accepted as valid. A regression in BackedArenaAllocator when destroying it could cause a crash. Fixed macOS regression which was breaking stack traces. Compiler fixes¶ $stringify would sometimes wrap output in extra parentheses. constdef vector with an alias was incorrectly lowered The compiler asserted when concatenating a struct to an untypedlist untypedlist was not detected as invalid as an enum associated-value type or as a pointer Thank yous¶ Again, this release wouldn't have been possible without the C3 community. I'd like to extend a deep thank you to all who have contributed, both through filed issues, PRs and just plain discussions.

PR contributors for this release¶ Stdlib: AtomicSynth, Book-reader, GuineaPigUuhh and Manu Linares Compiler & toolchain: Book-reader, Johannes Müller, Manu Linares, Osama Badeeb, rickyadastra and Rodrigo Camacho CI/Infrastructure: Hade and Manu Linares Change Log¶ Click for full change log Changes / improvements¶ @weak now works with all declarations. Add @align for asm blocks to stack align them. Stack alignment is no longer default. Allow setting Windows subsystem directly. Add bitoffset and bitsize reflection properties to bitstruct members. #3219 Improve error message on trying to cast char array to String. #3343 Add Foo::is_generic(...), Foo::generic_qname and Foo::generic_args. #2909 #3329 Add own, init and drop parameter annotations. constdef can now be generic. Libraries can now expose reusable target configurations via a templates map in their manifest, which projects reference from a target using template: "library/template". Properties from the template are loaded first and can be overridden by target-local settings. Stdlib changes¶ Atomic.compare_exchange added. Added array::contains_slice and array::index_of_slice. String.index_of and rindex_of will now accept finding empty strings. Add log::register_dynamic_category, for libraries that wish to define their own categories dynamically. Fixes¶ $stringify would sometimes include parens. Regression when destroying a BackedArenaAllocator in some cases #3332. "a::b:c:d:e:f:0" was not parsed as a valid ipv6 string. constdef vector with alias incorrectly lowered #3335. Compiler asserts on concatenating a struct to an untypedlist #3326. untypedlist was not detected as invalid in enum associated value type or as a pointer #3342. Regression using non-posix libc. Crash with an optional struct recursively defined with a function type. #3358 Denormal results were not handled correctly by String.to_double(). A float literal with an uppercase 'F' suffix would be a double instead of a float. Json serialization would not correctly handle unicode and \v. #

3353 Semantic checking was incorrect in the case of &a - &b where one or both are optional and the result isn't assigned. Regression on MacOS, breaking stack trace. Want To Dive Into C3?¶ Check out the documentation or download it and try it out. Have questions? Come and chat with us on Discord.