It is a way to indicate to the compiler that the line can't be reached.
On some configurations, it does happen to trap, as desired. Use a
function that always traps, since that's the intent.
This is phase-1 of switching from llvm::Optional to std::optional in the
next rebranch. llvm::Optional was removed from upstream LLVM, so we need
to migrate off rather soon. On Darwin, std::optional, and llvm::Optional
have the same layout, so we don't need to be as concerned about ABI
beyond the name mangling. `llvm::Optional` is only returned from one
function in
```
getStandardTypeSubst(StringRef TypeName,
bool allowConcurrencyManglings);
```
It's the return value, so it should not impact the mangling of the
function, and the layout is the same as `std::optional`, so it should be
mostly okay. This function doesn't appear to have users, and the ABI was
already broken 2 years ago for concurrency and no one seemed to notice
so this should be "okay".
I'm doing the migration incrementally so that folks working on main can
cherry-pick back to the release/5.9 branch. Once 5.9 is done and locked
away, then we can go through and finish the replacement. Since `None`
and `Optional` show up in contexts where they are not `llvm::None` and
`llvm::Optional`, I'm preparing the work now by going through and
removing the namespace unwrapping and making the `llvm` namespace
explicit. This should make it fairly mechanical to go through and
replace llvm::Optional with std::optional, and llvm::None with
std::nullopt. It's also a change that can be brought onto the
release/5.9 with minimal impact. This should be an NFC change.
I thought this was me being more standard but I keep on hitting this so I am
returning back to an assert(0) version of this. This is only enabled if NDEBUG
is set, so this is ok.
This will just make them easier to update over time since adding a new function
doesn't require one to renumber the /entire/ file... *face-palm*.
Originally the reason why I added this is b/c I need to ensure that we handle
all errors exactly once so making sure we control the exact amount of emitted
errors is important. I can still do this with the new approach by just doing
per-function max error counts. Thus I also in this commit added FileCheck
patterns that implemented this scheme so now we have everything.
This is doing a few things with a simple change to use a builder:
1. It cleans up how we emit errors so we have a builder object that constructs
errors. The errors then just become dumb POD data that the builder vends to
callers that via the boolean values describe what errors were found.
2. Now that we have one place where we are actually emitting these errors, I
cleaned up how we emit the errors by normalizing the output so function names
are quoted the same.
3. I changed our error emission so that we emit a unique count of the errors as
we emit them. This makes it so that our pattern matching is much more robust
against weird pattern match errors that can be difficult to debug due to the
errors having unrelated test cases/file check patterns bleed
together. Before/end checks eliminate this problem. I updated all of the
relevant test cases.
The reason /why/ I am doing this though is that I am going to be adding support
to the LinearLifetimeChecker for flagging objects that are outside of the
lifetime that we are verifying (meaning either before or after). This is going
to cause me to need to track /all/ non consuming uses when performing linear
lifetime checks and thus most likely emit more errors. I was finding it to be
difficult to update the current tests given the state of the world before this
patch, so I was inspired to clean this up to satisfy practical as well as debt
concerns.
Specifically, I split it into 3 initial categories: IR, Utils, Verifier. I just
did this quickly, we can always split it more later if we want.
I followed the model that we use in SILOptimizer: ./lib/SIL/CMakeLists.txt vends
a macro (sil_register_sources) to the sub-folders that register the sources of
the subdirectory with a global state variable that ./lib/SIL/CMakeLists.txt
defines. Then after including those subdirs, the parent cmake declares the SIL
library. So the output is the same, but we have the flexibility of having
subdirectories to categorize source files.
