Some of these upgrades are a prerequisite for supporting Visual Studio 2026 with CMake > 3.5 (#17017).

Dropping legacy libpcre entirely because there is probably no support for modern CMake. It doesn't seem to be used anywhere in the Windows workflow, so this is a good cleanup anyway. check-in: 6735bf10d8 user: julien@portalier.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, release/1.20

Prevents excessive expansion of aliases. check-in: cac321391b user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, release/1.20

Prevents stack overflows when parsing a deeply nested YAML file. check-in: 17ef7a78f5 user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, release/1.20

Enables execution contexts by default by replacing the :execution_context flag with an ugly check for not :without_mt and not :preview_mt or :execution_context in the runtime, where feature detection such as checking if Fiber::ExecutionContext exits isn't always reliable (due to load order and macro expansions).

Replaces :preview_mt flag for thread safety in stdlib with new :without_mt flag. The preview_mt mode is still supported by the legacy Crystal::Scheduler, but has been deprecated.

Replaces some :execution_context flags with :without_mt, namely the memory barriers in the ARM and AArch64 fiber context switch assembly and the fiber stack pool.

The interpreter can't start threads, yet, so the :without_mt flag is always set. check-in: 987c2eb3ee user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, master

JobObject is quite complex and the completion event isn't guaranteed to be delivered. Instead we can use RegisterWaitForSingleObject to execute a callback in an IO thread to post the IOCP completion event. check-in: 88a7dab9c0 user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, master

With execution contexts, we can leverage Fiber.syscall to detach the blocking fiber during ReadConsoleW (if it blocks for too long).

Without MT (and with preview MT), we can directly pass the result through the request object. check-in: 551a1f7a48 user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, master

This parameter is only useful for `-Dpreview_mt`. Execution contexts require a different approach (concurrent context). check-in: db504818e9 user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, master

This PR fixes encoding operations on long strings by ignoring `Errno::E2BIG` errors.

FWIW, this will need additional testing to ensure that strings with non-ASCII characters still work, but the test included with this PR fails without this patch and passes with it. check-in: a16ef75756 user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, master

Co-authored-by: straight-shoota <466378+straight-shoota@users.noreply.github.com> Co-authored-by: Johannes Müller <straightshoota@gmail.com> check-in: 0640c68a61 user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, master

Otherwise we risk a double enqueue. This was made visible by the io_uring evloop where shutdown now yields the calling fiber, while other event loops block. check-in: d0e1760ee2 user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, master

Moves the `#overlapped_connect` and `#overlapped_accept` methods from `System::Socket` into `EventLoop::IOCP` as its the sole caller of these methods, so the interations are now system/socket -> evloop/iocp -> system/iocp with less back and forth.

Co-authored-by: Sijawusz Pur Rahnama <sija@sija.pl> check-in: 10fd3a31ab user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, master

When `-Dwithout_main` is set, Crystal does not generate the default C `main` function or the platform-specific main entry point.

This is useful for shared libraries and embedded use cases that provide their own C ABI entry points. check-in: 458172655f user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, master

Using the new process API from #16773

Co-authored-by: Julien Portalier <julien@portalier.com> check-in: ad7ef6eb5a user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, master

Makes `when Foo, Bar; x` equivalent to `when Foo; x; when Bar; x;` with separate code branches and separated type restrictions, instead forming a union (`Foo | Bar`). Explicit `when Union(Foo, Bar)` enables the old behaviour. This should be fully backwards compatible. check-in: 581ce4dae3 user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, master

This is a follow-up to #17069, migrating to the native format of rumdl. The configuration does not change.

This enables rumdl to pick up the exclude configuration (it reads `.markdownlint.yml` but not `.markdownlintignore`). check-in: b8c182b68b user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, master

This reverts commit f38c6d949faaab055cf9bf2ee176b7acaac2d91c.

It causes some yet unidentified codegen failure: #17077 check-in: be79585969 user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, master

Co-authored-by: straight-shoota <466378+straight-shoota@users.noreply.github.com> check-in: 605452887b user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, master

As outlined in https://github.com/crystal-lang/crystal/pull/17063#issuecomment-4685448325 by @stevegeek: the quick-path (between the uncontended fast-path and the slow-path) for unlocking was using an *and* when it should have been using an *or* in the conditions (just like in the slow-path).

Running benchmarks, it seems to have a slight impact in some cases (far more threads than CPU cores + enough contention), but given that the slow path has the correct conditions, the impact is low.

Co-authored-by: Stephen Ierodiaconou <stevegeek@gmail.com> check-in: 354161672b user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, master

The shorthand flag `-p` for `crystal spec -- --profile` is in conflict with the shorthand flag `-p` for `crystal spec --progress`.

This patch removes the short flag from `crystal spec --help` and suggests passing runner options after `--`. That solution still is not ideal, but keeps existing commands working compared to removing `-p` from the spec runner entirely. check-in: d13a1de0b2 user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, master

Disable read-ahead on the transport when the context enables kTLS, so OpenSSL sees every byte and kTLS-RX engages cleanly.

Since kTLS bypasses the transport, records are read straight from the kernel, we need to ensure there's no data that can get "stuck" in buffers as we switch from userspace to kernel.

Fixes #16881

Co-authored-by: Julien Portalier <julien@portalier.com> check-in: 7c2e692ebe user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, master

The operation was already using overlapped on Windows/IOCP but outside the event loop. The operation can also run async on Linux/io_uring.

The polling event loops now consider that `pread` can return `EAGAIN` in an edge case: disk files are always ready, and a fifo/pipe isn't seekable, but a character device can.

Also enables `pread` on WASI. check-in: 1c6e8693ac user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, master

[rumdl](https://rumdl.dev/) is a Markdown linter similar to [markdownlint](https://github.com/igorshubovych/markdownlint-cli) but with some significant improvements. It is compatible with markdownlint, supporting the same rules and configuration as before. It's a drop-in replacement with more performance (Rust vs Javascript). And it brings a bunch of additional rules and features, such as per-file-ignores. See https://rumdl.dev/markdownlint-comparison/ for a full comparison.

We already applied the same change in https://github.com/crystal-lang/crystal-website/pull/1082 check-in: 2d9cf2ba3f user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, master

When cross compiling, the compiler used to emit before the actual codegen and bypassed the cache to directly emit the object file to the current folder.

We now call the regular codegen path (sequential one because only one compilation unit), then emit files to the current folder. We still always emit the object file to be consistent with the current behavior and with the `build` command that always generates an executable. check-in: 35345a0d66 user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, master

`Process.exec` doesn't work as expected on Windows, so we explicitly spawn a subprocess and return its status.

We should eventually replace this with a portable stdlib method (see https://github.com/crystal-lang/crystal/issues/14422). check-in: 60046c29ec user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, master

Co-authored-by: straight-shoota <466378+straight-shoota@users.noreply.github.com> check-in: 867c444f7d user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, master

This adds integration specs for the compiler's command line interface.

`external_command_spec.cr` was already such a spec, but part of the primitives suite for the lack of a better place. check-in: 852a33a83c user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, master

Mirrors the same options available on `JSON::Field` and `YAML::Field`. check-in: fedec420e4 user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, master

Co-authored-by: Johannes Müller <straightshoota@gmail.com> check-in: 6924f83be2 user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, master

Co-authored-by: straight-shoota <466378+straight-shoota@users.noreply.github.com> check-in: ca6a1b6f7a user: noreply@github.com tags: tcl-tk, trunk, feature/tar, release/0.16, feature/jm-time-formats-simplified, opt/io-buffered-each-byte, release/1.1, feature/enforce-hash-key-types, release/1.3, compiler/ident, feat/tool-dependencies-clean, release/1.10, release/1.9, ci/feat/docs-generator-iframe, ci/infra/make-man, master