Summary:
CFG generation is expected to fail in this case, but it should not crash.
Also added a test that reproduces the crash.
Reviewers: klimek
Subscribers: cfe-commits
Patch by Martin Boehme!
Differential Revision: http://reviews.llvm.org/D21895
llvm-svn: 274834
These ExprWithCleanups are added for holding a RunCleanupsScope not
for destructor calls; rather, they are for lifetime marks. This requires
ExprWithCleanups to keep a bit to indicate whether it have cleanups with
side effects (e.g. dtor calls).
Differential Revision: http://reviews.llvm.org/D20498
llvm-svn: 272296
This patch corresponds to reviews:
http://reviews.llvm.org/D15120http://reviews.llvm.org/D19125
It adds support for the __float128 keyword, literals and target feature to
enable it. Based on the latter of the two aforementioned reviews, this feature
is enabled on Linux on i386/X86 as well as SystemZ.
This is also the second attempt in commiting this feature. The first attempt
did not enable it on required platforms which caused failures when compiling
type_traits with -std=gnu++11.
If you see failures with compiling this header on your platform after this
commit, it is likely that your platform needs to have this feature enabled.
llvm-svn: 268898
Since this patch provided support for the __float128 type but disabled it
on all platforms by default, some platforms can't compile type_traits with
-std=gnu++11 since there is a specialization with __float128.
This reverts the patch until D19125 is approved (i.e. we know which platforms
need this support enabled).
llvm-svn: 266460
This patch corresponds to review:
http://reviews.llvm.org/D15120
It adds support for the __float128 keyword, literals and a target feature to
enable it. This support is disabled by default on all targets and any target
that has support for this type is free to add it.
Based on feedback that I've received from target maintainers, this appears to
be the right thing for most targets. I have not heard from the maintainers of
X86 which I believe supports this type. I will subsequently investigate the
impact of enabling this on X86.
llvm-svn: 266186
Putting OpenCLImageTypes.def to clangAST library violates layering requirement: "It's not OK for a Basic/ header to include an AST/ header".
This fixes the modules build.
Differential revision: http://reviews.llvm.org/D18954
Reviewers: Richard Smith, Vassil Vassilev.
llvm-svn: 266180
I. Current implementation of images is not conformant to spec in the following points:
1. It makes no distinction with respect to access qualifiers and therefore allows to use images with different access type interchangeably. The following code would compile just fine:
void write_image(write_only image2d_t img);
kernel void foo(read_only image2d_t img) { write_image(img); } // Accepted code
which is disallowed according to s6.13.14.
2. It discards access qualifier on generated code, which leads to generated code for the above example:
call void @write_image(%opencl.image2d_t* %img);
In OpenCL2.0 however we can have different calls into write_image with read_only and wite_only images.
Also generally following compiler steps have no easy way to take different path depending on the image access: linking to the right implementation of image types, performing IR opts and backend codegen differently.
3. Image types are language keywords and can't be redeclared s6.1.9, which can happen currently as they are just typedef names.
4. Default access qualifier read_only is to be added if not provided explicitly.
II. This patch corrects the above points as follows:
1. All images are encapsulated into a separate .def file that is inserted in different points where image handling is required. This avoid a lot of code repetition as all images are handled the same way in the code with no distinction of their exact type.
2. The Cartesian product of image types and image access qualifiers is added to the builtin types. This simplifies a lot handling of access type mismatch as no operations are allowed by default on distinct Builtin types. Also spec intended access qualifier as special type qualifier that are combined with an image type to form a distinct type (see statement above - images can't be created w/o access qualifiers).
3. Improves testing of images in Clang.
Author: Anastasia Stulova
Reviewers: bader, mgrang.
Subscribers: pxli168, pekka.jaaskelainen, yaxunl.
Differential Revision: http://reviews.llvm.org/D17821
llvm-svn: 265783
Change body autosynthesis to use the BodyFarm-synthesized body even when
an actual body exists. This enables the analyzer to use the simpler,
analyzer-provided body to model the behavior of the function rather than trying
to understand the actual body. Further, this makes the analyzer robust against
changes in headers that expose the implementations of those bodies.
rdar://problem/25145950
llvm-svn: 264687
When looking up the 'self' decl in block captures, make sure to find the actual
self declaration even when the block captures a local variable named 'self'.
rdar://problem/24751280
llvm-svn: 261703
Now that the libcpp implementations of these methods has a branch that doesn't call
memmove(), the analyzer needs to invalidate the destination for these methods explicitly.
rdar://problem/23575656
llvm-svn: 260043
These sets perform linear searching in small mode so it is never a good
idea to use SmallSize/N bigger than 32.
Differential Revision: http://reviews.llvm.org/D16705
llvm-svn: 259284
Add "enum ObjCPropertyQueryKind" to a few APIs that used to only take the name
of the property: ObjCPropertyDecl::findPropertyDecl,
ObjCContainerDecl::FindPropertyDeclaration,
ObjCInterfaceDecl::FindPropertyVisibleInPrimaryClass,
ObjCImplDecl::FindPropertyImplDecl, and Sema::ActOnPropertyImplDecl.
ObjCPropertyQueryKind currently has 3 values:
OBJC_PR_query_unknown, OBJC_PR_query_instance, OBJC_PR_query_class
This extra parameter specifies that we are looking for an instance property with
the given name, or a class property with the given name, or any property with
the given name (if both exist, the instance property will be returned).
rdar://23891898
llvm-svn: 259070
After r251874, readonly properties that are shadowed by a readwrite property
in a class extension no longer have an instance variable, which caused the body
farm to not synthesize getters. Now, if a readonly property does not have an
instance variable look for a shadowing property and try to get the instance
variable from there.
rdar://problem/24060091
llvm-svn: 258886
Summary:
This patch is provided in preparation for removing autoconf on 1/26. The proposal to remove autoconf on 1/26 was discussed on the llvm-dev thread here: http://lists.llvm.org/pipermail/llvm-dev/2016-January/093875.html
"This is the way [autoconf] ends
Not with a bang but a whimper."
-T.S. Eliot
Reviewers: chandlerc, grosbach, bob.wilson, echristo
Subscribers: klimek, cfe-commits
Differential Revision: http://reviews.llvm.org/D16472
llvm-svn: 258862
This prevents spurious dead store warnings when a C++ lambda is casted to a block.
I've also added several tests documenting our still-incomplete support for lambda-to-block
casts.
rdar://problem/22236293
llvm-svn: 254107
Rather than storing BeforeInfo in the DenseMap by value, this stores a
unique_ptr to it, so that we can keep a pointer to it live across
subsequent DenseMap insertions.
This change also removes the unique_ptr wrapper around BeforeVect
because now we're indirecting at a higher level.
llvm-svn: 253694
When calling a ObjC method on super from inside a C++ lambda, look at the
captures to find "self". This mirrors how the analyzer handles calling super in
an ObjC block and fixes an assertion failure.
rdar://problem/23550077
llvm-svn: 253176
Summary:
VisitReturnStmt would create a new block with including Dtors, so the Dtors created
in VisitCompoundStmts would be in an unreachable block.
Example:
struct S {
~S();
};
void f()
{
S s;
return;
}
void g()
{
S s;
}
Before this patch, f has one additional unreachable block containing just the
destructor of S. With this patch, both f and g have the same blocks.
Reviewers: krememek
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D13973
llvm-svn: 253107
Summary: It breaks the build for the ASTMatchers
Subscribers: klimek, cfe-commits
Differential Revision: http://reviews.llvm.org/D13893
llvm-svn: 250827
Prior to this patch, -Wtautological-overlap-compare would only warn us
if there was a sketchy logical comparison between variables and
IntegerLiterals. This patch makes -Wtautological-overlap-compare aware
of EnumConstantDecls, so it can apply the same logic to them.
llvm-svn: 249053
This fixes PR16833, in which the analyzer was using large amounts of memory
for switch statements with large case ranges.
rdar://problem/14685772
A patch by Aleksei Sidorin!
Differential Revision: http://reviews.llvm.org/D5102
llvm-svn: 248318
ConsumedBlockInfo objects were move assigned, but only in a state where
the dtor was a no-op anyway. Subtle and easily could've happened in ways
that wouldn't've been safe - so this change makes it safe no matter what
state the ConsumedBlockInfo object is in.
llvm-svn: 244998
Turns out the one place that relied on the implicit copy ctor was safe
because it created an object in a state where the dtor was a no-op, but
that's more luck that good management.
Sure up the API by defining move construction and using it, which
implicitly disallows the unreliable copy operations.
llvm-svn: 244968
In llvm commit r243581, a reverse range adapter was added which allows
us to change code such as
for (auto I = Fields.rbegin(), E = Fields.rend(); I != E; ++I) {
in to
for (const FieldDecl *I : llvm::reverse(Fields))
This commit changes a few of the places in clang which are eligible to use
this new adapter.
llvm-svn: 243663
StmtRange was just a convenient wrapper for two StmtIterators before
we had real range support. This removes some of the implicit conversions
StmtRange had leading to slightly more verbose code but also should make
more obvious what's going on. No functional change intended.
llvm-svn: 242615
Objective-C format strings now support modifier flags
that can be attached to a '@' conversion. Currently
the only one supported, as of iOS 9 and OS X 10.11,
is the new "technical term", denoted by the flag "tt",
for example:
%[tt]@
instead of just:
%@
The 'tt' stands for "technical term", which is used
by the string-localization facilities on Darwin to
add the appropriate spacing or quotation depending
the language locale.
Implements <rdar://problem/20374720>.
llvm-svn: 241243
The patch is generated using this command:
$ tools/extra/clang-tidy/tool/run-clang-tidy.py -fix \
-checks=-*,llvm-namespace-comment -header-filter='llvm/.*|clang/.*' \
work/llvm/tools/clang
To reduce churn, not touching namespaces spanning less than 10 lines.
llvm-svn: 240270
Includes a simple static analyzer check and not much else, but we'll also
be able to take advantage of this in Swift.
This feature can be tested for using __has_feature(cf_returns_on_parameters).
This commit also contains two fixes:
- Look through non-typedef sugar when deciding whether something is a CF type.
- When (cf|ns)_returns(_not)?_retained is applied to invalid properties,
refer to "property" instead of "method" in the error message.
rdar://problem/18742441
llvm-svn: 240185
Summary:
This patch is part of http://llvm-reviews.chandlerc.com/D2181.
In-class initializers are appended to the CFG when CFGBuilder::addInitializer is called.
Reviewers: jordan_rose, rsmith
Reviewed By: jordan_rose
Subscribers: cfe-commits, klimek
Differential Revision: http://reviews.llvm.org/D2370
llvm-svn: 238913
When checking if a function is noreturn, consider a codepath to be noreturn if
the path destroys a class and the class destructor, base class destructors, or
member field destructors are marked noreturn.
Differential Revision: http://reviews.llvm.org/D9454
llvm-svn: 238382
Previously we'd try to perform checks on the captures from the middle of
parsing the lambda's body, at the point where we detected that a variable
needed to be captured. This was wrong in a number of subtle ways. In
PR23334, we couldn't correctly handle the list of potential odr-uses
resulting from the capture, and our attempt to recover from that resulted
in a use-after-free.
We now defer building the initialization expression until we leave the lambda
body and return to the enclosing context, where the initialization does the
right thing. This patch only covers lambda-expressions, but we should apply
the same change to blocks and captured statements too.
llvm-svn: 235921
GCC -pedantic produces a format warning when the "%p" specifier is used with
arguments that are not void*. It's useful for portability to be able to
catch such warnings with clang as well. The warning is off by default in
both gcc and with this patch. This patch enables it either when extensions
are disabled with -pedantic, or with the specific flag -Wformat-pedantic.
The C99 and C11 specs do appear to require arguments corresponding to 'p'
specifiers to be void*: "If any argument is not the correct type for the
corresponding conversion specification, the behavior is undefined."
[7.19.6.1 p9], and of the 'p' format specifier "The argument shall be a
pointer to void." [7.19.6.1 p8]
Both printf and scanf format checking are covered.
llvm-svn: 231211
`isTrackedVar` has been updated to also track records.
`DeclRefExpr`s appearing on the left side of a comma operator are
ignored, while those appearing on the right side are classified as
`Use`.
Patch by Enrico Pertoso.
llvm-svn: 231068
This adds a new __freebsd_kprintf__ format string type, which enables
checking when used in __attribute__((format(...))) attributes. It can
check the FreeBSD kernel specific %b, %D, %r and %y specifiers, using
existing diagnostic messages. Also adds test cases for all these
specifiers.
Differential Revision: http://reviews.llvm.org/D7154
llvm-svn: 229921
std::lock_guard. If EXCLUSIVE_LOCKS_REQUIRED is placed on the constructor of
a SCOPED_LOCKABLE class, then that constructor is assumed to adopt the lock;
e.g. the lock must be held on construction, and will be released on destruction.
llvm-svn: 228194
These checks detect potential deadlocks caused by inconsistent lock
ordering. The checks are implemented under the -Wthread-safety-beta flag.
This patch also replaces calls to getAttrs() with calls to attrs() throughout
ThreadSafety.cpp, which fixes the earlier issue that cause assert failures.
llvm-svn: 228051
These checks detect potential deadlocks caused by inconsistent lock
ordering. The checks are implemented under the -Wthread-safety-beta flag.
llvm-svn: 227997
Sorry for the noise, I managed to miss a bunch of recent regressions of
include orderings here. This should actually sort all the includes for
Clang. Again, no functionality changed, this is just a mechanical
cleanup that I try to run periodically to keep the #include lines as
regular as possible across the project.
llvm-svn: 225979
A patch by Daniel DeFreez!
We were previously dropping edges on re-declarations. Store the
canonical declarations in the graph to ensure that different
references to the same function end up reflected with the same call graph
node.
(Note, this might lead to performance fluctuation because call graph
is used to determine the function analysis order.)
llvm-svn: 224398
Bitfield RefersToEnclosingLocal of Stmt::DeclRefExprBitfields renamed to RefersToCapturedVariable to reflect latest changes introduced in commit 224323. Also renamed method Expr::refersToEnclosingLocal() to Expr::refersToCapturedVariable() and comments for constant arguments.
No functional changes.
llvm-svn: 224329
warns when a guarded variable is passed by reference as a function argument.
This is released as a separate warning flag, because it could potentially
break existing code that uses thread safety analysis.
llvm-svn: 218087
Numerous changes, including:
* Changed the way variables and instructions are handled in basic blocks to
be more efficient.
* Eliminated SExprRef.
* Simplified futures.
* Fixed documentation.
* Compute dominator and post dominator trees.
llvm-svn: 217556
off by default, issue a warning if %s directive is used in
certain CF/NS formatting APIs, to assist user in deprecating
use of such %s in these APIs. rdar://18182443
llvm-svn: 217467
Scoped lockable objects (mutex guards) are implemented as if it is a
lock itself that is acquired upon construction and unlocked upon
destruction. As it if course needs to be used to actually lock down
something else (a mutex), it keeps track of this knowledge through its
underlying mutex field in its FactEntry.
The problem with this approach is that this only allows us to lock down
a single mutex, so extend the code to use a vector of underlying
mutexes. This, however, makes the code a bit more complex than
necessary, so subclass FactEntry into LockableFactEntry and
ScopedLockableFactEntry and move all the logic that differs between
regular locks and scoped lockables into member functions.
llvm-svn: 217016
Fix r216438 to catch more complicated self-initialized in std::move. For
instance, "Foo f = std::move(cond ? OtherFoo : (UNUSED_VALUE, f));"
Make sure that BinaryConditionalOperator, ConditionalOperator, BinaryOperator
with comma operator, and OpaqueValueExpr perform the correct usage forwarding
across the three uninitialized value checkers.
llvm-svn: 216627
Currently the analyzer lazily models some functions using 'BodyFarm',
which constructs a fake function implementation that the analyzer
can simulate that approximates the semantics of the function when
it is called. BodyFarm does this by constructing the AST for
such definitions on-the-fly. One strength of BodyFarm
is that all symbols and types referenced by synthesized function
bodies are contextual adapted to the containing translation unit.
The downside is that these ASTs are hardcoded in Clang's own
source code.
A more scalable model is to allow these models to be defined as source
code in separate "model" files and have the analyzer use those
definitions lazily when a function body is needed. Among other things,
it will allow more customization of the analyzer for specific APIs
and platforms.
This patch provides the initial infrastructure for this feature.
It extends BodyFarm to use an abstract API 'CodeInjector' that can be
used to synthesize function bodies. That 'CodeInjector' is
implemented using a new 'ModelInjector' in libFrontend, which lazily
parses a model file and injects the ASTs into the current translation
unit.
Models are currently found by specifying a 'model-path' as an
analyzer option; if no path is specified the CodeInjector is not
used, thus defaulting to the current behavior in the analyzer.
Models currently contain a single function definition, and can
be found by finding the file <function name>.model. This is an
initial starting point for something more rich, but it bootstraps
this feature for future evolution.
This patch was contributed by Gábor Horváth as part of his
Google Summer of Code project.
Some notes:
- This introduces the notion of a "model file" into
FrontendAction and the Preprocessor. This nomenclature
is specific to the static analyzer, but possibly could be
generalized. Essentially these are sources pulled in
exogenously from the principal translation.
Preprocessor gets a 'InitializeForModelFile' and
'FinalizeForModelFile' which could possibly be hoisted out
of Preprocessor if Preprocessor exposed a new API to
change the PragmaHandlers and some other internal pieces. This
can be revisited.
FrontendAction gets a 'isModelParsingAction()' predicate function
used to allow a new FrontendAction to recycle the Preprocessor
and ASTContext. This name could probably be made something
more general (i.e., not tied to 'model files') at the expense
of losing the intent of why it exists. This can be revisited.
- This is a moderate sized patch; it has gone through some amount of
offline code review. Most of the changes to the non-analyzer
parts are fairly small, and would make little sense without
the analyzer changes.
- Most of the analyzer changes are plumbing, with the interesting
behavior being introduced by ModelInjector.cpp and
ModelConsumer.cpp.
- The new functionality introduced by this change is off-by-default.
It requires an analyzer config option to enable.
llvm-svn: 216550
to recover the performance after r214064.
Also sorts out the naming for PostOrderCFGView, ReversePostOrderCFGView,
BackwardDataflowWorklist and ForwardDataflowWorklist, to match the accepted
terminology.
Also unifies BackwardDataflowWorklist and ForwardDataflowWorklist to share
the "worklist for prioritization, post-order traversal for fallback" logic,
and to avoid repetitive sorting.
Also cleans up comments in the affected area.
llvm-svn: 215650
As we only create temp dtor decision branches when a temp dtor needs to
be run (as opposed to for each logical branch in the original
expression), we must include the information about all previous logical
branches when we annotate the temp dtor decision branch.
llvm-svn: 215188
If the truth value of a LHS is known, we can build the knowledge whether
a temporary destructor is executed or not into the CFG. This is needed
by the return type analysis.
llvm-svn: 215118
Changes to the original patch:
- model the CFG for temporary destructors in conditional operators so that
the destructors of the true and false branch are always exclusive. This
is necessary because we must not have impossible paths for the path
based analysis to work.
- add multiple regression tests with ternary operators
Original description:
Fix modelling of non-lifetime-extended temporary destructors in the
analyzer.
Changes to the CFG:
When creating the CFG for temporary destructors, we create a structure
that mirrors the branch structure of the conditionally executed
temporary constructors in a full expression.
The branches we create use a CXXBindTemporaryExpr as terminator which
corresponds to the temporary constructor which must have been executed
to enter the destruction branch.
2. Changes to the Analyzer:
When we visit a CXXBindTemporaryExpr we mark the CXXBindTemporaryExpr as
executed in the state; when we reach a branch that contains the
corresponding CXXBindTemporaryExpr as terminator, we branch out
depending on whether the corresponding CXXBindTemporaryExpr was marked
as executed.
llvm-svn: 215096
This reverts commit r214962 because after the change the
following code doesn't compile with -Wreturn-type -Werror.
#include <cstdlib>
class NoReturn {
public:
~NoReturn() __attribute__((noreturn)) { exit(1); }
};
int check() {
true ? NoReturn() : NoReturn();
}
llvm-svn: 214998
1. Changes to the CFG:
When creating the CFG for temporary destructors, we create a structure
that mirrors the branch structure of the conditionally executed
temporary constructors in a full expression.
The branches we create use a CXXBindTemporaryExpr as terminator which
corresponds to the temporary constructor which must have been executed
to enter the destruction branch.
2. Changes to the Analyzer:
When we visit a CXXBindTemporaryExpr we mark the CXXBindTemporaryExpr as
executed in the state; when we reach a branch that contains the
corresponding CXXBindTemporaryExpr as terminator, we branch out
depending on whether the corresponding CXXBindTemporaryExpr was marked
as executed.
llvm-svn: 214962
MaterializeTemporaryExpr already contains information about the lifetime
of the temporary; if the lifetime is not the full statement, we do not
want to emit a destructor at the end of the full statement for it.
llvm-svn: 214292
til::SExpr. This is a large patch, with many small changes to pretty printing
and expression lowering to make the new SExpr representation equivalent in
functionality to the old.
llvm-svn: 214089
lambda expressions (other than their capture initializers) nor blocks. Do walk
into default argument expressions and default initializer expressions.
These bugs were causing us to produce broken CFGs whenever a lambda expression
was used to initialize a libstdc++ std::function object!
llvm-svn: 214050
Fixes a crash in Retain Count checker error reporting logic by handing
the allocation statement retrieval from a BlockEdge program point.
Also added a simple CFG dump routine for debugging.
llvm-svn: 210960
will never be true in a well-defined context. The checking for null pointers
has been moved into the caller logic so it does not rely on undefined behavior.
llvm-svn: 210498
This change is a precondition to the proposed change to handle temporary
dtors correctly.
The idea is to explicitly search for the next return that doesn't have other
paths into it (that is, if the current block is dead, the block containing the
return must be dead, too). Thus, introducing non-control-flow block
transitions will not break the logic.
llvm-svn: 209531
The thread safety analysis isn't very useful in ObjC (you can't annotate
ObjC classes or methods) but we can still analyze the actual code and
show violations in usage of C/C++ functions.
Fixes PR19541, which does not use thread safety attributes but crashes
with -Weverything.
llvm-svn: 208436
The assignment needs to be before the destruction of the temporary.
This patch calls out to addStmt, which invokes VisitDeclStmt, which has
all the correct logic for handling temporaries.
llvm-svn: 207985
definition below all of the header #include lines, clang edition.
If you want more details about this, you can see some of the commits to
Debug.h in LLVM recently. This is just the clang section of a cleanup
I've done for all uses of DEBUG_TYPE in LLVM.
llvm-svn: 206849
* Adds an iterator_range interface to CallExpr to get the arguments
* Modifies SExpr such that it must be allocated in the Arena, and cannot be deleted
* Minor const-correctness and nullptr updates
* Adds some operator!= implementations to complement operator==
* Removes unused functionality
llvm-svn: 205915
This patch is the first part of a significant refactoring that seeks to restore
sanity to way thread safety analysis deals with capability expressions. The
current patch merely provides an outline of the structure of the new system.
It's not yet connected to the actual analysis, so there's no change in
functionality.
llvm-svn: 205728
which warns on compound conditionals that always evaluate to the same value.
For instance, (x > 5 && x < 3) will always be false since no value for x can
satisfy both conditions.
This patch also changes the CFG to use these tautological values for better
branch analysis. The test for -Wunreachable-code shows how this change catches
additional dead code.
Patch by Anders Rönnholm.
llvm-svn: 205665
Taking a hint from -Wparentheses, use an extra '()' as a sigil that
a dead condition is intentionally dead. For example:
if ((0)) { dead }
When this sigil is found, do not emit a dead code warning. When the
analysis sees:
if (0)
it suggests inserting '()' as a Fix-It.
llvm-svn: 205069
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
Richard Smith