This commit makes some big changes to how we track state for Zig source
files. In particular, it changes:
* How `File` tracks its path on-disk
* How AstGen discovers files
* How file-level errors are tracked
* How `builtin.zig` files and modules are created
The original motivation here was to address incremental compilation bugs
with the handling of files, such as #22696. To fix this, a few changes
are necessary.
Just like declarations may become unreferenced on an incremental update,
meaning we suppress analysis errors associated with them, it is also
possible for all imports of a file to be removed on an incremental
update, in which case file-level errors for that file should be
suppressed. As such, after AstGen, the compiler must traverse files
(starting from analysis roots) and discover the set of "live files" for
this update.
Additionally, the compiler's previous handling of retryable file errors
was not very good; the source location the error was reported as was
based only on the first discovered import of that file. This source
location also disappeared on future incremental updates. So, as a part
of the file traversal above, we also need to figure out the source
locations of imports which errors should be reported against.
Another observation I made is that the "file exists in multiple modules"
error was not implemented in a particularly good way (I get to say that
because I wrote it!). It was subject to races, where the order in which
different imports of a file were discovered affects both how errors are
printed, and which module the file is arbitrarily assigned, with the
latter in turn affecting which other files are considered for import.
The thing I realised here is that while the AstGen worker pool is
running, we cannot know for sure which module(s) a file is in; we could
always discover an import later which changes the answer.
So, here's how the AstGen workers have changed. We initially ensure that
`zcu.import_table` contains the root files for all modules in this Zcu,
even if we don't know any imports for them yet. Then, the AstGen
workers do not need to be aware of modules. Instead, they simply ignore
module imports, and only spin off more workers when they see a by-path
import.
During AstGen, we can't use module-root-relative paths, since we don't
know which modules files are in; but we don't want to unnecessarily use
absolute files either, because those are non-portable and can make
`error.NameTooLong` more likely. As such, I have introduced a new
abstraction, `Compilation.Path`. This type is a way of representing a
filesystem path which has a *canonical form*. The path is represented
relative to one of a few special directories: the lib directory, the
global cache directory, or the local cache directory. As a fallback, we
use absolute (or cwd-relative on WASI) paths. This is kind of similar to
`std.Build.Cache.Path` with a pre-defined list of possible
`std.Build.Cache.Directory`, but has stricter canonicalization rules
based on path resolution to make sure deduplicating files works
properly. A `Compilation.Path` can be trivially converted to a
`std.Build.Cache.Path` from a `Compilation`, but is smaller, has a
canonical form, and has a digest which will be consistent across
different compiler processes with the same lib and cache directories
(important when we serialize incremental compilation state in the
future). `Zcu.File` and `Zcu.EmbedFile` both contain a
`Compilation.Path`, which is used to access the file on-disk;
module-relative sub paths are used quite rarely (`EmbedFile` doesn't
even have one now for simplicity).
After the AstGen workers all complete, we know that any file which might
be imported is definitely in `import_table` and up-to-date. So, we
perform a single-threaded graph traversal; similar to what
`resolveReferences` plays for `AnalUnit`s, but for files instead. We
figure out which files are alive, and which module each file is in. If a
file turns out to be in multiple modules, we set a field on `Zcu` to
indicate this error. If a file is in a different module to a prior
update, we set a flag instructing `updateZirRefs` to invalidate all
dependencies on the file. This traversal also discovers "import errors";
these are errors associated with a specific `@import`. With Zig's
current design, there is only one possible error here: "import outside
of module root". This must be identified during this traversal instead
of during AstGen, because it depends on which module the file is in. I
tried also representing "module not found" errors in this same way, but
it turns out to be much more useful to report those in Sema, because of
use cases like optional dependencies where a module import is behind a
comptime-known build option.
For simplicity, `failed_files` now just maps to `?[]u8`, since the
source location is always the whole file. In fact, this allows removing
`LazySrcLoc.Offset.entire_file` completely, slightly simplifying some
error reporting logic. File-level errors are now directly built in the
`std.zig.ErrorBundle.Wip`. If the payload is not `null`, it is the
message for a retryable error (i.e. an error loading the source file),
and will be reported with a "file imported here" note pointing to the
import site discovered during the single-threaded file traversal.
The last piece of fallout here is how `Builtin` works. Rather than
constructing "builtin" modules when creating `Package.Module`s, they are
now constructed on-the-fly by `Zcu`. The map `Zcu.builtin_modules` maps
from digests to `*Package.Module`s. These digests are abstract hashes of
the `Builtin` value; i.e. all of the options which are placed into
"builtin.zig". During the file traversal, we populate `builtin_modules`
as needed, so that when we see this imports in Sema, we just grab the
relevant entry from this map. This eliminates a bunch of awkward state
tracking during construction of the module graph. It's also now clearer
exactly what options the builtin module has, since previously it
inherited some options arbitrarily from the first-created module with
that "builtin" module!
The user-visible effects of this commit are:
* retryable file errors are now consistently reported against the whole
file, with a note pointing to a live import of that file
* some theoretical bugs where imports are wrongly considered distinct
(when the import path moves out of the cwd and then back in) are fixed
* some consistency issues with how file-level errors are reported are
fixed; these errors will now always be printed in the same order
regardless of how the AstGen pass assigns file indices
* incremental updates do not print retryable file errors differently
between updates or depending on file structure/contents
* incremental updates support files changing modules
* incremental updates support files becoming unreferenced
Resolves: #22696
These were previously incremental tests, so weren't running. They didn't
*need* to be incremental. They worked under the old runner because of
how it directly integrated with the compiler so tracked error messages
differently.
This rewrite improves some error messages, hugely simplifies the logic,
and fixes several bugs. One of these bugs is technically a new rule
which Andrew and I agreed on: if a parameter has a comptime-only type
but is not declared `comptime`, then the corresponding call argument
should not be *evaluated* at comptime; only resolved. Implementing this
required changing how function types work a little, which in turn
required allowing a new kind of function coercion for some generic use
cases: function coercions are now allowed to implicitly *remove*
`comptime` annotations from parameters with comptime-only types. This is
okay because removing the annotation affects only the call site.
Resolves: #22262
I pointed a fuzzer at the tokenizer and it crashed immediately. Upon
inspection, I was dissatisfied with the implementation. This commit
removes several mechanisms:
* Removes the "invalid byte" compile error note.
* Dramatically simplifies tokenizer recovery by making recovery always
occur at newlines, and never otherwise.
* Removes UTF-8 validation.
* Moves some character validation logic to `std.zig.parseCharLiteral`.
Removing UTF-8 validation is a regression of #663, however, the existing
implementation was already buggy. When adding this functionality back,
it must be fuzz-tested while checking the property that it matches an
independent Unicode validation implementation on the same file. While
we're at it, fuzzing should check the other properties of that proposal,
such as no ASCII control characters existing inside the source code.
Other changes included in this commit:
* Deprecate `std.unicode.utf8Decode` and its WTF-8 counterpart. This
function has an awkward API that is too easy to misuse.
* Make `utf8Decode2` and friends use arrays as parameters, eliminating a
runtime assertion in favor of using the type system.
After this commit, the crash found by fuzzing, which was
"\x07\xd5\x80\xc3=o\xda|a\xfc{\x9a\xec\x91\xdf\x0f\\\x1a^\xbe;\x8c\xbf\xee\xea"
no longer causes a crash. However, I did not feel the need to add this
test case because the simplified logic eradicates most crashes of this
nature.
Introduce the concept of "target query" and "resolved target". A target
query is what the user specifies, with some things left to default. A
resolved target has the default things discovered and populated.
In the future, std.zig.CrossTarget will be rename to std.Target.Query.
Introduces `std.Build.resolveTargetQuery` to get from one to the other.
The concept of `main_mod_path` is gone, no longer supported. You have to
put the root source file at the module root now.
* remove deprecated API
* update build.zig for the breaking API changes in this branch
* move std.Build.Step.Compile.BuildId to std.zig.BuildId
* add more options to std.Build.ExecutableOptions, std.Build.ObjectOptions,
std.Build.SharedLibraryOptions, std.Build.StaticLibraryOptions, and
std.Build.TestOptions.
* remove `std.Build.constructCMacro`. There is no use for this API.
* deprecate `std.Build.Step.Compile.defineCMacro`. Instead,
`std.Build.Module.addCMacro` is provided.
- remove `std.Build.Step.Compile.defineCMacroRaw`.
* deprecate `std.Build.Step.Compile.linkFrameworkNeeded`
- use `std.Build.Module.linkFramework`
* deprecate `std.Build.Step.Compile.linkFrameworkWeak`
- use `std.Build.Module.linkFramework`
* move more logic into `std.Build.Module`
* allow `target` and `optimize` to be `null` when creating a Module.
Along with other fields, those unspecified options will be inherited
from parent `Module` when inserted into an import table.
* the `target` field of `addExecutable` is now required. pass `b.host`
to get the host target.
This commit introduces the new `ref_coerced_ty` result type into AstGen.
This represents a expression which we want to treat as an lvalue, and
the pointer will be coerced to a given type.
This change gives known result types to many expressions, in particular
struct and array initializations. This allows certain casts to work
which previously required explicitly specifying types via `@as`. It also
eliminates our dependence on anonymous struct types for expressions of
the form `&.{ ... }` - this paves the way for #16865, and also results
in less Sema magic happening for such initializations, also leading to
potentially better runtime code.
As part of these changes, this commit also implements #17194 by
disallowing RLS on explicitly-typed struct and array initializations.
Apologies for linking these changes - it seemed rather pointless to try
and separate them, since they both make big changes to struct and array
initializations in AstGen. The rationale for this change can be found in
the proposal - in essence, performing RLS whilst maintaining the
semantics of the intermediary type is a very difficult problem to solve.
This allowed the problematic `coerce_result_ptr` ZIR instruction to be
completely eliminated, which in turn also simplified the logic for
inferred allocations in Sema - thanks to this, we almost break even on
line count!
In doing this, the ZIR instructions surrounding these initializations
have been restructured - some have been added and removed, and others
renamed for clarity (and their semantics changed slightly). In order to
optimize ZIR tag count, the `struct_init_anon_ref` and
`array_init_anon_ref` instructions have been removed in favour of using
`ref` on a standard anonymous value initialization, since these
instructions are now virtually never used.
Lastly, it's worth noting that this commit introduces a slightly strange
source of generic poison types: in the expression `@as(*anyopaque, &x)`,
the sub-expression `x` has a generic poison result type, despite no
generic code being involved. This turns out to be a logical choice,
because we don't know the result type for `x`, and the generic poison
type represents precisely this case, providing the semantics we need.
Resolves: #16512Resolves: #17194
The changes to result locations and generic calls has caused mild
changes to some compile errors. Some are slightly better, some slightly
worse, but none of the changes are major.
There are now very few stage1 cases remaining:
* `cases/compile_errors/stage1/obj/*` currently don't work correctly on
stage2. There are 6 of these, and most of them are probably fairly
simple to fix.
* `cases/compile_errors/async/*` and all remaining `safety/*` depend on
async; see #6025.
Resolves: #14849
Instead of using `zig test` to build a special version of the compiler
that runs all the test-cases, the zig build system is now used as much
as possible - all with the basic steps found in the standard library.
For incremental compilation tests (the ones that look like foo.0.zig,
foo.1.zig, foo.2.zig, etc.), a special version of the compiler is
compiled into a utility executable called "check-case" which checks
exactly one sequence of incremental updates in an independent
subprocess. Previously, all incremental and non-incremental test cases
were done in the same test runner process.
The compile error checking code is now simpler, but also a bit
rudimentary, and so it additionally makes sure that the actual compile
errors do not include *extra* messages, and it makes sure that the
actual compile errors output in the same order as expected. It is also
based on the "ends-with" property of each line rather than the previous
logic, which frankly I didn't want to touch with a ten-meter pole. The
compile error test cases have been updated to pass in light of these
differences.
Previously, 'error' mode with 0 compile errors was used to shoehorn in a
different kind of test-case - one that only checks if a piece of code
compiles without errors. Now there is a 'compile' mode of test-cases,
and 'error' must be only used when there are greater than 0 errors.
link test cases are updated to omit the target object format argument
when calling checkObject since that is no longer needed.
The test/stage2 directory is removed; the 2 files within are moved to be
directly in the test/ directory.
* Scan from line start when finding tag in tokenizer
This resolves a crash that can occur for invalid bytes like carriage
returns that are valid characters when not parsed from within literals.
There are potentially other edge cases this could resolve as well, as
the calling code for this function didn't account for any potential
'pending_invalid_tokens' that could be queued up by the tokenizer from
within another state.
* Fix carriage return crash in multiline string
Follow the guidance of #38:
> However CR directly before NL is interpreted as only a newline and not part of the multiline string. zig fmt will delete the CR.
Zig fmt already had code for deleting carriage returns, but would still
crash - now it no longer does so. Carriage returns encountered before
line-feeds are now appropriately removed on program compilation as well.
* Only accept carriage returns before line feeds
Previous commit was much less strict about this, this more closely
matches the desired spec of only allow CR characters in a CRLF pair, but
not otherwise.
* Fix CR being rejected when used as whitespace
Missed this comment from ziglang/zig-spec#83:
> CR used as whitespace, whether directly preceding NL or stray, is still unambiguously whitespace. It is accepted by the grammar and replaced by the canonical whitespace by zig fmt.
* Add tests for carriage return handling
The container we want to get the fields from might not be declared in the
same file as the block we are analyzing, so we should get the AST from
the decl's file instead.
* `-Dskip-compile-errors` is removed; `-Dskip-stage1` is added.
* Use `std.testing.allocator` instead of a new instance of GPA.
- Fix the memory leaks this revealed.
* Show the file name when it is not parsed correctly such as when the
manifest is missing.
- Better error messages when test files are not parsed correctly.
* Ignore unknown files such as swap files.
* Move logic from declarative file to the test harness implementation.
* Move stage1 tests to stage2 tests where appropriate.
Some cases had to stay behind, either because they required complex case
configuration that we don't support in independent files yet, or because
they have associated comments which we don't want to lose track of.
To make sure I didn't drop any tests in the process, I logged all
obj/test/exe test cases from a run of "zig build test" and compared
before/after this change.
All of the test cases match, with two exceptions:
- "use of comptime-known undefined function value" was deleted, since
it was a duplicate
- "slice sentinel mismatch" was renamed to "vector index out of
bounds", since it was incorrectly named
This brings two quality-of-life improvements for folks working on
compile error test cases:
- test cases can be added/changed without re-building Zig
- wrapping the source in a multi-line string literal is not necessary
I decided to keep things as simple as possible for this initial
implementation. The test "manifest" is a contiguous comment block at the
end of the test file:
1. The first line is the test case name
2. The second line is a blank comment
2. The following lines are expected errors
Here's an example:
```zig
const U = union(enum(u2)) {
A: u8,
B: u8,
C: u8,
D: u8,
E: u8,
};
export fn entry() void {
_ = U{ .E = 1 };
}
// union with too small explicit unsigned tag type
//
// tmp.zig:1:22: error: specified integer tag type cannot represent every field
// tmp.zig:1:22: note: type u2 cannot fit values in range 0...4
```
The mode of the test (obj/exe/test), as well as the target
(stage1/stage2) is determined based on the directory containing the
test.
We'll probably eventually want to support embedding this information
in the test files themselves, similar to the arocc test runner, but
that enhancement can be tackled later.
The runtime behavior allowed this in both stage1 and stage2, but stage1
fails with index out of bounds during comptime. This behavior makes
sense to support, and comptime behavior should match runtime behavior. I
implement this fix only in stage2.
If a '(' is found where the continue expression was expected and it is
on the same line as the previous token issue an error about missing
colon before the continue expression.
For some errors if the found token is not on the same line as
the previous token, point to the end of the previous token.
This usually results in more helpful errors.
