Core issue 1013 suggests that having an uninitialied std::nullptr_t be
UB is a bit foolish, since there is only a single valid value. This DR
reports that DR616 fixes it, which does so by making lvalue-to-rvalue
conversions from nullptr_t be equal to nullptr.
However, just implementing that results in warnings/etc in many places.
In order to fix all situations where nullptr_t would seem uninitialized,
this patch instead (as an otherwise transparent extension) default
initializes uninitialized VarDecls of nullptr_t.
Differential Revision: https://reviews.llvm.org/D53713
Change-Id: I84d72a9290054fa55341e8cbdac43c8e7f25b885
llvm-svn: 349201
This exposes a (known) CodeGen bug: it can't cope with emitting lvalue
expressions that denote non-odr-used but usable-in-constant-expression
variables. See PR39528 for a testcase.
Reverted for now until that issue can be fixed.
llvm-svn: 346065
nullptr_t does not access memory.
We now reuse CK_NullToPointer to represent a conversion from a glvalue
of type nullptr_t to a prvalue of nullptr_t where necessary.
llvm-svn: 345562
When reporting certain kinds of analyzer warnings, we use the
bugreporter::trackNullOrUndefValue mechanism, which is part of public checker
API, to understand where a zero, null-pointer, or garbage value came from,
which would highlight important events with respect to that value in the
diagnostic path notes, and help us suppress various false positives that result
from values appearing from particular sources.
Previously, we've lost track of the value when it was written into a memory
region that is not a plain variable. Now try to resume tracking in this
situation by finding where the last write to this region has occured.
Differential revision: https://reviews.llvm.org/D41253
llvm-svn: 321130
This function can now track null pointer through simple pointer arithmetic,
such as '*&*(p + 2)' => 'p' and so on, displaying intermediate diagnostic pieces
for the user to understand where the null pointer is coming from.
Differential Revision: https://reviews.llvm.org/D37025
llvm-svn: 314290
The original intent of this commit was to catch potential null dereferences
early, but it breaks the common "home-grown offsetof" idiom (PR13927):
(((struct Foo *)0)->member - ((struct foo *)0))
As it turns out, this appears to be legal in C, per a footnote in
C11 6.5.3.2: "Thus, &*E is equivalent to E (even if E is a null pointer)".
In C++ this issue is still open:
http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#232
We'll just have to make sure we have good path notes in the future.
This reverts r164441 / 9be016dcd1ca3986873a7b66bd4bc027309ceb59.
llvm-svn: 164958
We want to catch cases like this early, so that we can produce better
diagnostics and path notes:
Point *p = 0;
int *px = &p->x; // should warn here
*px = 1;
llvm-svn: 164441
Original commit message:
Provide -Wnull-conversion separately from -Wconversion.
Like GCC, provide a NULL conversion to non-pointer conversion as a separate
flag, on by default. GCC's flag is "conversion-null" which we provide for
cross compatibility, but in the interests of consistency (with
-Wint-conversion, -Wbool-conversion, etc) the canonical Clang flag is called
-Wnull-conversion.
Patch by Lubos Lunak.
Review feedback by myself, Chandler Carruth, and Chad Rosier.
llvm-svn: 152774
Like GCC, provide a NULL conversion to non-pointer conversion as a separate
flag, on by default. GCC's flag is "conversion-null" which we provide for
cross compatibility, but in the interests of consistency (with
-Wint-conversion, -Wbool-conversion, etc) the canonical Clang flag is called
-Wnull-conversion.
Patch by Lubos Lunak.
Review feedback by myself, Chandler Carruth, and Chad Rosier.
llvm-svn: 152745
Erich Keane