We can safely switch to insert_range here because
SyntheticStmtSourceMap starts out empty in the constructor. Also
TheCFG->synthetic_stmts() comes from DenseMap, so we know that the
keys are unique. That is, operator[] and insert are equivalent in
this particular case.
This eliminates false positives in bugprone-use-after-move where a
variable
is used in the callee and moved from in the arguments.
We introduce one special case: If the callee is a MemberExpr with a
DeclRefExpr as its base, we consider it to be sequenced after the
arguments. This is because the variable referenced in the base will only
actually be accessed when the call happens, i.e. once all of the
arguments have been evaluated. This has no basis in the C++ standard,
but it reflects actual behavior that is relevant to a use-after-move
scenario:
```c++
a.bar(consumeA(std::move(a));
```
In this example, we end up accessing a after it has been moved from,
even though nominally the callee a.bar is evaluated before the argument
consumeA(std::move(a)).
Treating this scenario correctly has required rewriting the logic in
bugprone-use-after-move that governs whether the use happens in a later
loop iteration than the move. This was previously based on an unsound
heuristic (does the use come lexically before the move?); we now use a
more rigourous criterion based on reachability in the CFG.
Fixes#57758Fixes#59612
Co-authored-by: martinboehme <mboehme@google.com>
As designated initializers show up only in the syntactic form of the
InitListExpr, we need to make sure we're searching both forms of the
InitListExpr when determining successors in the evaluation order.
This fixes a bug in bugprone-use-after-move where previously we erroneously
concluded that two designated initializers were unsequenced. The newly added
tests fail without the fix.
Differential Revision: https://reviews.llvm.org/D145906
The only part of ASTContext.h that requires most AST types to be
complete is the parent map. Nothing in Clang proper uses the ParentMap,
so split it out into its own class. Make ASTContext own the
ParentMapContext so there is still a one-to-one relationship.
After this change, 562 fewer files depend on ASTTypeTraits.h, and 66
fewer depend on TypeLoc.h:
$ diff -u deps-before.txt deps-after.txt | \
grep '^[-+] ' | sort | uniq -c | sort -nr | less
562 - ../clang/include/clang/AST/ASTTypeTraits.h
340 + ../clang/include/clang/AST/ParentMapContext.h
66 - ../clang/include/clang/AST/TypeLocNodes.def
66 - ../clang/include/clang/AST/TypeLoc.h
15 - ../clang/include/clang/AST/TemplateBase.h
...
I computed deps-before.txt and deps-after.txt with `ninja -t deps`.
This removes a common and key dependency on TemplateBase.h and
TypeLoc.h.
This also has the effect of breaking the ParentMap RecursiveASTVisitor
instantiation into its own file, which roughly halves the compilation
time of ASTContext.cpp (29.75s -> 17.66s). The new file takes 13.8s to
compile.
I left behind forwarding methods for getParents(), but clients will need
to include a new header to make them work:
#include "clang/AST/ParentMapContext.h"
I noticed that this parent map functionality is unfortunately duplicated
in ParentMap.h, which only works for Stmt nodes.
Reviewed By: rsmith
Differential Revision: https://reviews.llvm.org/D71313
Summary:
The bugprone-use-after-move check exhibits false positives for certain uses of
the C++17 if/switch init statements. These false positives are caused by a bug
in the ExprSequence calculations.
This revision adds tests for the false positives and fixes the corresponding
sequence calculation.
Reviewers: gribozavr
Subscribers: xazax.hun, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D67292
llvm-svn: 371396
to reflect the new license.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351636
Summary:
Before this fix, the bugprone-use-after-move check could incorrectly
conclude that a use and move in a function template were not sequenced.
For details, see
https://bugs.llvm.org/show_bug.cgi?id=39149
Reviewers: alexfh, hokein, aaron.ballman, JonasToth
Reviewed By: aaron.ballman
Subscribers: xazax.hun, cfe-commits
Tags: #clang-tools-extra
Differential Revision: https://reviews.llvm.org/D52782
llvm-svn: 343768
