This commit makes the user-facing StdLibExtras templates and utilities
arguably more nice-looking by removing the need to reach into the
wrapper structs generated by them to get the value/type needed.
The C++ standard library had to invent `_v` and `_t` variants (likely
because of backwards compat), but we don't need to cater to any codebase
except our own, so might as well have good things for free. :^)
(...and ASSERT_NOT_REACHED => VERIFY_NOT_REACHED)
Since all of these checks are done in release builds as well,
let's rename them to VERIFY to prevent confusion, as everyone is
used to assertions being compiled out in release.
We can introduce a new ASSERT macro that is specifically for debug
checks, but I'm doing this wholesale conversion first since we've
accumulated thousands of these already, and it's not immediately
obvious which ones are suitable for ASSERT.
Thanks to @trflynn89 for the neat implicit consteval ctor trick!
This allows us to basically slap `CheckedFormatString` on any
formatting function, and have its format argument checked at compiletime.
Note that there is a validator bug where it doesn't parse inner replaced
fields like `{:~>{}}` correctly (what should be 'left align with next
argument as size' is parsed as `{:~>{` following a literal closing
brace), so the compiletime checks are disabled on these temporarily by
forcing them to be StringViews.
This commit also removes the now unused `AK::StringLiteral` type (which
was introduced for use with NTTP strings).
This currently breaks the OSS-Fuzz build, and attempts to make it build
with clang >= 12 were unsuccessful, so let's just disable dbgln() checks
for any clang version.
This reverts commit 338bb73289.
This didn't work, the OSS-Fuzz build (using clang 12) is still failing.
We'll just disable dbgln() checks when compiling with any clang for now.
This checks the following things:
- No unclosed braces in format string
`dbgln("a:{}}", a)` where the '}}' would be interpreted as a
literal '}'
`dbgln("a:{", a)` where someone with a faulty keyboard like mine
could generate
- No extra closed braces in format string
`dbgln("a:{{}", a)` where the '{{' would interpreted as a literal '{'
`dbgln("a:}", a)` where someone with a faulty keyboard could
generate
- No references to nonexistent arguments
`dbgln("a:{} b:{}", a)` where the value of `b` is not in the
arguments list
- No unconsumed argument
`dbgln("a:{1}", not_used, 1)` where `not_used` is extraneous
Problem:
- Many constructors are defined as `{}` rather than using the ` =
default` compiler-provided constructor.
- Some types provide an implicit conversion operator from `nullptr_t`
instead of requiring the caller to default construct. This violates
the C++ Core Guidelines suggestion to declare single-argument
constructors explicit
(https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#c46-by-default-declare-single-argument-constructors-explicit).
Solution:
- Change default constructors to use the compiler-provided default
constructor.
- Remove implicit conversion operators from `nullptr_t` and change
usage to enforce type consistency without conversion.
I ran into this exact but at least twenty times in Serenity alone. The
C++ Standard dictates that 'unsigned long' and 'unsigned long long' are
distinct types even though on most platforms they are usually both 64
bit integers.
Also it wasn't possible to evaluate IsIntegral<T> for types that were
not integers since it used MakeUnsigned<T> internally.
This commit also removes a few functions like raw_out and vwarn. If we
want to write raw output, we can do this as follows:
out("{}", "Hello, World!");
The vout stuff isn't really public API anyways, so no need for another
vwarn.
We are adding the process name as prefix and a newline as suffix to any
message written to debug. Thus, the following doesn't make any sense:
for (u8 byte : bytes)
dbg("{:02x} ", byte);
dbgln();
Which function call would put the prefix? This doesn't make any sense,
thus these functions must go.
The example above could be converted to:
StringBuilder builder;
for (u8 byte : bytes)
builder.appendff("{:02x} ", byte);
dbgln("{}", builder.build());
Problem:
- m_data is being passed to the constructor of the parent class before
it is initialized. This is not really a problem because the compiler
knows the location and it is only a span being constructed, but it
triggers a warning in clang for use-before-init.
Solution:
- Initialize using a default constructed array and then overwrite it
inside the constructor after the member is initialized.
String literals are just pointers to a constant character. It should be
possible to format them as such. (The default is to print them as
strings still.)
When we write the format specifier '{:#08x}' we are asking for eight
significant digits, zero padding and the prefix '0x'.
However, previously we got only six significant digits because the
prefix counted towards the width. (The number '8' here is the total
width and not the number of significant digits.)
Both fmtlib and printf shared this behaviour. However, I am introducing
a special case here because when we do zero padding we really only care
about the digits and not the width.
Notice that zero padding is a special case anyways, because zero padding
goes after the prefix as opposed to any other padding which goes before
it.
In the future all (normal) output should be written by any of the
following functions:
out (currently called new_out)
outln
dbg (currently called new_dbg)
dbgln
warn (currently called new_warn)
warnln
However, there are still a ton of uses of the old out/warn/dbg in the
code base so the new functions are called new_out/new_warn/new_dbg. I am
going to rename them as soon as all the other usages are gone (this
might take a while.)
I also added raw_out/raw_dbg/raw_warn which don't do any escaping,
this should be useful if no formatting is required and if the input
contains tons of curly braces. (I am not entirely sure if this function
will stay, but I am adding it for now.)
It's now save to pass a signed integer as parameter and then use it as
replacement field (previously, this would just cast it to size_t which
would be bad.)
Instead of just implementing format specifiers ad-hog this commit
implements the exact syntax std::format uses.
There are still a ton of features that are not supported by this
implementation, however, the format specifiers should be parsed
correctly.
In some cases however, the format specifiers aren't quite parsed
correctly, for example:
String::formatted("{:{}}", 42, 4)
should produce the string " 42" however an (unrelated) assertion fails.
This is because vformat doesn't consider nested parentheses. I have to
spend some time coming up with a simple way of doing this, I don't feel
like doing that right now.
The fundamental code for this already exists, by limiting the number of
format arguments (arbitrarily) to 256 large widths are used to encode
that these should be taken from other format parameters.
With this commit, <AK/Format.h> has a more supportive role and isn't
used directly.
Essentially, there now is a public 'vformat' function ('v' for vector)
which takes already type erased parameters. The name is choosen to
indicate that this function behaves similar to C-style functions taking
a va_list equivalent.
The interface for frontend users are now 'String::formatted' and
'StringBuilder::appendff'.
This function is not avaliable in the kernel.
In the future it would be nice to have some sort of <charconv> header
that does this for all integer types and then call it in strtoull and et
cetera.
The difference would be that this function say 'from_chars' would return
an Optional and not just interpret anything invalid as zero.
