The exception is return statements that include control-flow,
which are clearly doing something "interesting".
99% of the cases I examined for -Wunreachable-code that fired
on return statements were not interesting enough to warrant
being in -Wunreachable-code by default. Thus the move to
include them in -Wunreachable-code-return.
This simplifies a bunch of logic, including removing the ad hoc
logic to look for std::string literals.
llvm-svn: 204307
Also relax unreachable 'break' and 'return' to not check for being
preceded by a call to 'noreturn'. That turns out to not be so
interesting in practice.
llvm-svn: 204000
Recent work on -Wunreachable-code has focused on suppressing uninteresting
unreachable code that center around "configuration values", but
there are still some set of cases that are sometimes interesting
or uninteresting depending on the codebase. For example, a dead
"break" statement may not be interesting for a particular codebase,
potentially because it is auto-generated or simply because code
is written defensively.
To address these workflow differences, -Wunreachable-code is now
broken into several diagnostic groups:
-Wunreachable-code: intended to be a reasonable "default" for
most users.
and then other groups that turn on more aggressive checking:
-Wunreachable-code-break: warn about dead break statements
-Wunreachable-code-trivial-return: warn about dead return statements
that return "trivial" values (e.g., return 0). Other return
statements that return non-trivial values are still reported
under -Wunreachable-code (this is an area subject to more refinement).
-Wunreachable-code-aggressive: supergroup that enables all these
groups.
The goal is to eventually make -Wunreachable-code good enough to
either be in -Wall or on-by-default, thus finessing these warnings
into different groups helps achieve maximum signal for more users.
TODO: the tests need to be updated to reflect this extra control
via diagnostic flags.
llvm-svn: 203994
This can possibly be refined later, but right now the experience
is so incomprehensible for a user to understand what is going on
this isn't a useful warning.
llvm-svn: 203336
I had forgotten that the same reachability code is used by both -Wreturn-type
and -Wunreachable-code, so the heuristics applied to the latter were indirectly
impacting the former.
To address this, the reachability code is more refactored so that whiled
the logic at its core is shared, the intention of the clients are better
captured and segregated in helper APIs.
Fixes PR19074, and also some false positives reported offline to me
by Nick Lewycky.
llvm-svn: 203209
I have mixed feelings about this one. It's used all over the codebase,
and is analogous to the current heuristic for ordinary C string literals.
This requires some ad hoc pattern matching of the AST. While the
test case mirrors what we see std::string in libc++, it's not really
testing the libc++ headers.
llvm-svn: 203091
Sometimes do..while() is used to create a scope that can be left early.
In such cases, the unreachable 'while()' test is not usually interesting
unless it actually does something that is observable.
llvm-svn: 203051
Sometimes do..while() is used to create a scope that can be left early.
In such cases, the unreachable 'while()' test is not usually interesting
unless it actually does something that is observable.
llvm-svn: 203036
Previously we only pruned dead returns preceded by a call to a
'noreturn' function. After looking at the results of the LLVM codebase,
there are many others that should be pruned as well.
llvm-svn: 203029
Some unreachable code is only "sometimes unreachable" because it
is guarded by a configuration value that is determined at compile
time and is always constant. Sometimes those represent real bugs,
but often they do not. This patch causes the reachability analysis
to cover such branches even if they are technically unreachable
in the CFG itself. There are some conservative heuristics at
play here to determine a "configuration value"; these are intended
to be refined over time.
llvm-svn: 202912
This is a heuristic. Many switch statements, although they look covered
over an enum, may actually handle at runtime more values than in the enum.
This is overly conservative, as there are some cases that clearly
can be ruled as being clearly unreachable, e.g. 'switch (42) { case 1: ... }'.
We can refine this later.
llvm-svn: 202436
For example:
unreachable();
break;
This code is idiomatic and defensive. The fact that 'break' is
unreachable here is not interesting. This occurs frequently
in LLVM/Clang itself.
llvm-svn: 202328
This is to support some analyses, like -Wunreachable-code, that
will need to recover the original unprunned CFG edges in order
to suppress issues that aren't really bugs in practice.
There are two important changes here:
- AdjacentBlock replaces CFGBlock* for CFG successors/predecessors.
This has the size of 2 pointers, instead of 1. This is unlikely
to have a significant memory impact on Sema since a single
CFG usually exists at one time, but could impact the memory
usage of the static analyzer. This could possibly be optimized
down to a single pointer with some cleverness.
- Predecessors can now contain null predecessors, which means
some analyses doing a reverse traversal will need to take into
account. This already exists for successors, which contain
successor slots for specific branch kinds (e.g., 'if') that
expect a fixed number of successors, even if a branch is
not reachable.
llvm-svn: 202325
This does;
- clang_tablegen() adds each tblgen'd target to global property CLANG_TABLEGEN_TARGETS as list.
- List of targets is added to LLVM_COMMON_DEPENDS.
- all clang libraries and targets depend on generated headers.
You might wonder this would be regression, but in fact, this is little loss.
- Almost all of clang libraries depend on tblgen'd files and clang-tblgen.
- clang-tblgen may cause short stall-out but doesn't cause unconditional rebuild.
- Each library's dependencies to tblgen'd files might vary along headers' structure.
It made hard to track and update *really optimal* dependencies.
Each dependency to intrinsics_gen and ClangSACheckers is left as DEPENDS.
llvm-svn: 201842
The following attributes have been (silently) deprecated, with their replacements listed:
lockable => capability
exclusive_locks_required => requires_capability
shared_locks_required => requires_shared_capability
locks_excluded => requires_capability
There are no functional changes intended.
llvm-svn: 201585
This implements FIXME from Checker.cpp (FIXME: We want to return the package + name of the checker here.) and replaces hardcoded checker names with the new ones obtained via getCheckName().getName().
llvm-svn: 201525
A return type is the declared or deduced part of the function type specified in
the declaration.
A result type is the (potentially adjusted) type of the value of an expression
that calls the function.
Rule of thumb:
* Declarations have return types and parameters.
* Expressions have result types and arguments.
llvm-svn: 200082
If there are non-trivially-copyable types /other/ than C++ records, we
won't have a synthesized copy expression, but we can't just use a simple
load/return.
Also, add comments and shore up tests, making sure to test in both ARC
and non-ARC.
llvm-svn: 199869
Fix a perennial source of confusion in the clang type system: Declarations and
function prototypes have parameters to which arguments are supplied, so calling
these 'arguments' was a stretch even in C mode, let alone C++ where default
arguments, templates and overloading make the distinction important to get
right.
Readability win across the board, especially in the casting, ADL and
overloading implementations which make a lot more sense at a glance now.
Will keep an eye on the builders and update dependent projects shortly.
No functional change.
llvm-svn: 199686
consumable objects. These are useful for implementing error codes that
must be checked. Patch also includes some significant refactoring, which was
necesary to implement the new behavior.
llvm-svn: 199169
In an expression like "new (a, b) Foo(x, y)", two things happen:
- Memory is allocated by calling a function named 'operator new'.
- The memory is initialized using the constructor for 'Foo'.
Currently the analyzer only models the second event, though it has special
cases for both the default and placement forms of operator new. This patch
is the first step towards properly modeling both events: it changes the CFG
so that the above expression now generates the following elements.
1. a
2. b
3. (CFGNewAllocator)
4. x
5. y
6. Foo::Foo
The analyzer currently ignores the CFGNewAllocator element, but the next
step is to treat that as a call like any other.
The CFGNewAllocator element is not added to the CFG for analysis-based
warnings, since none of them take advantage of it yet.
llvm-svn: 199123
...by synthesizing their body to be "return self->_prop;", with an extra
nudge to RetainCountChecker to still treat the value as +0 if we have no
other information.
This doesn't handle weak properties, but that's mostly correct anyway,
since they can go to nil at any time. This also doesn't apply to properties
whose implementations we can't see, since they may not be backed by an
ivar at all. And finally, this doesn't handle properties of C++ class type,
because we can't invoke the copy constructor. (Sema has actually done this
work already, but the AST it synthesizes is one the analyzer doesn't quite
handle -- it has an rvalue DeclRefExpr.)
Modeling setters is likely to be more difficult (since it requires
handling strong/copy), but not impossible.
<rdar://problem/11956898>
llvm-svn: 198953
encodes the canonical rules for LLVM's style. I noticed this had drifted
quite a bit when cleaning up LLVM, so wanted to clean up Clang as well.
llvm-svn: 198686
This has the dual effect of (1) enabling more dead-stripping in release builds
and (2) ensuring that debug helper functions aren't stripped away in debug
builds, as they're intended to be called from the debugger.
Note that the attribute is applied to definitions rather than declarations in
headers going forward because it's now conditional on NDEBUG:
/// \brief Mark debug helper function definitions like dump() that should not be
/// stripped from debug builds.
Requires corresponding macro added in LLVM r198456.
llvm-svn: 198489
to determine if a move function is the std::move function. This allows functions
like std::__1::move to also be treated a the move function.
llvm-svn: 197445
This reverts commit r189090.
The original patch introduced regressions (see the added live-variables.* tests). The patch depends on the correctness of live variable analyses, which are not computed correctly. I've opened PR18159 to track the proper resolution to this problem.
The patch was a stepping block to r189746. This is why part of the patch reverts temporary destructor tests that started crashing. The temporary destructors feature is disabled by default.
llvm-svn: 196593
Earlier versions discarded the state too soon, and did not track state changes,
e.g. when passing a temporary to a move constructor. Patch by
chris.wailes@gmail.com; review and minor fixes by delesley.
llvm-svn: 194900
The isLValueReferenceType function checks to see if the QualType's
canonical type is an LValue reference, and not if the QualType
itself is an LValue reference. This caused a segfault when trying
to cast the QualType's Type to a LValueReference. This is now
fixed by casting the result of getCanonicalType().
In addition, a test was added to isConsumableType to prevent
segfaults when a type being tested by the analysis is a reference
to a pointer or a pointer to a reference.
llvm-svn: 193751
* NamedDecl and CXXMethodDecl were missing getMostRecentDecl.
* The const version can just forward to the non const.
* getMostRecentDecl can use cast instead of cast_or_null.
This then removes some casts from the callers.
llvm-svn: 193039
Aaron Ballman