Without the packed qualifier, the type layout that we use to
initialize doesn't match the correct layout of the underlying
storage, causing corrupted data and past-the-end writes.
Thanks to Martin Storsjö for explaining this to me on IRC:
__USE_MINGW_ANSI_STDIO redirects stdio functions towards mingw-w64
reimplementations of them (since msvcrt.dll lacks lots of things). For
x86 with "long double", this is also needed to get long doubles
formatted properly. It's enabled by default by headers when building in
C99 mode, unless you're targeting UCRT. The headers normally enable this
automatically - or you can request it enabled with
-D__USE_MINGW_ANSI_STDIO=1. However, the mingw-w64-crt files are
expected to be built with this explicitly turned off. Since there's a
half dozen various ways of configuring the CRT and various features, the
mingw-w64-crt files specifically need to be built in a very hardcoded
configuration, which is different from how end user source files are
compiled.
This commit removes a patch that we were carrying previously.
See #7356
Addends in relocations are signed integers as theoretically it could
be a negative number. As Atom's offsets are relative to their parent
section, the relocation value should still result in a postive number.
For this reason, the final result is stored as an unsigned integer.
Also, rather than using `null` for relocations that do not support
addends. We set the value to 0 for those that do not support addends,
and have to call `addendIsPresent` to determine if an addend exists
or not. This means each Relocation costs 4 bytes less than before,
saving memory while linking.
The `producers` section contains meta data of the binary and/or
object file. It *can* contain the source language, the tool it
was processed by, and/or the SDK that was used to produce the file.
For now, we always set the language and processed-by fields to Zig.
In the future we will parse linked object files to detect their
producers sections and append (if different) their language, SDK
and processed-by fields.
Before this commit:
```
$ zig test lib/std/fs/test.zig --main-pkg-path lib/std --zig-lib-dir lib
2170 passed; 37 skipped; 0 failed.
```
After this commit:
```
$ zig test lib/std/fs/test.zig --main-pkg-path lib/std --zig-lib-dir lib
All 45 tests passed.
```
This matches stage1 behavior:
```
$ zig test -fstage1 lib/std/fs/test.zig --main-pkg-path lib/std --zig-lib-dir lib
All 45 tests passed.
```
All tests are still run if `zig test` is run directly on `lib/std/std.zig`:
```
$ zig test lib/std/std.zig --main-pkg-path lib/std --zig-lib-dir lib
2170 passed; 37 skipped; 0 failed.
```
`zig build test-std` is unaffected by this change.
Closes#12926
This was an accidental misuse of the Cache API which intends to call
resolve on all file paths going into it. This one callsite was failing
to do that; fixed now.
Fixes relative file paths from making it into the global cache manifest.
See #13050
expected type 'fn() void', found 'fn(i32) void'
function with 0 parameters cannot cast into a function with 0 parameters
=>
expected type 'fn() void', found 'fn(i32) void'
function with 1 parameters cannot cast into a function with 0 parameters
Superceeds PR #12735 (now supporting all packed structs in GNU C)
Fixes issue #12733
This stops translating C packed struct as a Zig packed struct.
Instead use a regular `extern struct` with `align(1)`.
This is because (as @Vexu explained) Zig packed structs are really just integers (not structs).
Alignment issue is more complicated. I think @ifreund was the
first to notice it in his comment on PR #12735
Justification of my interpretion of the C(lang) behavior
comes from a careful reading of the GCC docs for type & variable attributes:
(clang emulates gnu's packed attribute here)
The final line of the documentation for __attribute__ ((aligned)) [on types] says:
> When used on a struct, or struct member, *the aligned attribute can only increase the alignment*; in order to decrease it, the packed attribute must be specified as well.
This implies that GCC uses the `packed` attribute for alignment purposes
in addition to eliminating padding.
The documentation for __attribute__((packed)) [on types], states:
> This attribute, attached to a struct, union, or C++ class type definition, specifies that each of its members (other than zero-width bit-fields) is placed to minimize the memory required. **This is equivalent to specifying the packed attribute on each of the members**.
The key is resolving this indirection, and looking at the documentation
for __attribute__((packed)) [on fields (wierdly under "variables" section)]:
> The packed attribute specifies that a **structure member should have the smallest possible alignment** — one bit for a bit-field and one byte otherwise, unless a larger value is specified with the aligned attribute. The attribute does not apply to non-member objects.
Furthermore, alignment is the only effect of the packed attribute mentioned in the GCC docs (for "common" architecture).
Based on this, it seems safe to completely substitute C 'packed' with Zig 'align(1)'.
Target-specific or undocumented behavior potentially changes this.
Unfortunately, the current implementation of `translate-c` translates as
`packed struct` without alignment info.
Because Zig packed structs are really integers (as mentioned above),
they are the wrong interpretation and we should be using 'extern struct'.
Running `translate-c` on the following code:
```c
struct foo {
char a;
int b;
} __attribute__((packed));
struct bar {
char a;
int b;
short c;
__attribute__((aligned(8))) long d;
} __attribute__((packed));
```
Previously used a 'packed struct' (which was not FFI-safe on stage1).
After applying this change, the translated structures have align(1)
explicitly applied to all of their fields AS EXPECTED (unless explicitly overriden).
This makes Zig behavior for `tranlsate-c` consistent with clang/GCC.
Here is the newly produced (correct) output for the above example:
```zig
pub const struct_foo = extern struct {
a: u8 align(1),
b: c_int align(1),
};
pub const struct_bar = extern struct {
a: u8 align(1),
b: c_int align(1),
c: c_short align(1),
d: c_long align(8),
};
```
Also note for reference: Since the last stable release (0.9.1),
there was a change in the language spec
related to the alignment of packed structures.
The docs for Zig 0.9.1 read:
> Packed structs have 1-byte alignment.
So the old behavior of translate-c (not specifying any alignment) was possibly correct back then.
However the current docs read:
> Packed structs have the same alignment as their backing integer
Suggsestive both to the change to an integer-backed representation
which is incompatible with C's notation.
When encountering a fn type that returns an error (union), a backend
that supports error return tracing will want the StackTrace struct and
its fields to be analyzed.
