mirror of
https://github.com/llvm/llvm-project.git
synced 2025-04-17 19:26:36 +00:00
b9bca883c9
Based on the discussion in D82598#2171312. Thanks @NoQ!
D82598 is titled "Get rid of statement liveness, because such a thing doesn't
exist", and indeed, expressions express a value, non-expression statements
don't.
if (a && get() || []{ return true; }())
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ has a value
~ has a value
~~~~~~~~~~ has a value
~~~~~~~~~~~~~~~~~~~~ has a value
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ doesn't have a value
That is simple enough, so it would only make sense if we only assigned symbolic
values to expressions in the static analyzer. Yet the interface checkers can
access presents, among other strange things, the following two methods:
ProgramState::BindExpr(const Stmt *S, const LocationContext *LCtx, SVal V,
bool Invalidate=true)
ProgramState::getSVal(const Stmt *S, const LocationContext *LCtx)
So, what gives? Turns out, we make an exception for ReturnStmt (which we'll
leave for another time) and ObjCForCollectionStmt. For any other loops, in order
to know whether we should analyze another iteration, among other things, we
evaluate it's condition. Which is a problem for ObjCForCollectionStmt, because
it simply doesn't have one (CXXForRangeStmt has an implicit one!). In its
absence, we assigned the actual statement with a concrete 1 or 0 to indicate
whether there are any more iterations left. However, this is wildly incorrect,
its just simply not true that the for statement has a value of 1 or 0, we can't
calculate its liveness because that doesn't make any sense either, so this patch
turns it into a GDM trait.
Fixing this allows us to reinstate the assert removed in
https://reviews.llvm.org/rG032b78a0762bee129f33e4255ada6d374aa70c71.
Differential Revision: https://reviews.llvm.org/D86736
31 lines
365 B
Plaintext
31 lines
365 B
Plaintext
// RUN: %clang --analyze %s -fblocks
|
|
|
|
// https://reviews.llvm.org/D82598#2171312
|
|
|
|
@interface Item
|
|
// ...
|
|
@end
|
|
|
|
@interface Collection
|
|
// ...
|
|
@end
|
|
|
|
typedef void (^Blk)();
|
|
|
|
struct RAII {
|
|
Blk blk;
|
|
|
|
public:
|
|
RAII(Blk blk): blk(blk) {}
|
|
~RAII() { blk(); }
|
|
};
|
|
|
|
void foo(Collection *coll) {
|
|
RAII raii(^{});
|
|
for (Item *item in coll) {}
|
|
int i;
|
|
{
|
|
int j;
|
|
}
|
|
}
|