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.
When testing the Wasm linker for the producers section
we do not ever want to strip the binary as this will remove
the producers section in release-small.
This fixes the CI errors by d086b371f0e21e5029e1b0d05838b87502eb63e6
These tests will be failing on many platforms until #8465 is resolved.
Luckily, the particular function signature used for __divXc3 and __mulXc3
seems to be OK on x86-64.
These are the standard complex multiplication/division functions
required by the C standard (Annex G).
Don't get me started on the standard's handling of complex-infinity...
This also turns off non-debug modes for the bss linker tests for
Wasm. This is done as it's not required to guarantee to zero out
the bss section for non-debug modes.
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.
* the root struct decl name is fully qualified
this prevents error messages containing 'main.main'
* avoid declared here note when file struct is missing a member
It always points at the start of the file which might contain another
container misleading the user.
