Reapply [Sema] Add sizeof diagnostics for bzero

Reapply r277787. For memset (and others) we can get diagnostics like:

struct stat { int x; };
void foo(struct stat *stamps) {
bzero(stamps, s

Reapply [Sema] Add sizeof diagnostics for bzero

Reapply r277787. For memset (and others) we can get diagnostics like:

struct stat { int x; };
void foo(struct stat *stamps) {
bzero(stamps, sizeof(stamps));
memset(stamps, 0, sizeof(stamps));
}

t.c:7:28: warning: 'memset' call operates on objects of type 'struct stat' while the size is based on a different type 'struct stat *' [-Wsizeof-pointer-memaccess]
memset(stamps, 0, sizeof(stamps));
~~~~~~ ^~~~~~
t.c:7:28: note: did you mean to dereference the argument to 'sizeof' (and multiply it by the number of elements)?
memset(stamps, 0, sizeof(stamps));
^~~~~~

This patch implements the same class of warnings for bzero.

Differential Revision: https://reviews.llvm.org/D22525

rdar://problem/18963514

llvm-svn: 278264

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Revert "[Sema] Add sizeof diagnostics for bzero"

This reverts commit r277787, which caused PR28870.

llvm-svn: 277830

[Sema] Add sizeof diagnostics for bzero

For memset (and others) we can get diagnostics like:

struct stat { int x; };
void foo(struct stat *stamps) {
bzero(stamps, sizeof(stamps));
memse

[Sema] Add sizeof diagnostics for bzero

For memset (and others) we can get diagnostics like:

struct stat { int x; };
void foo(struct stat *stamps) {
bzero(stamps, sizeof(stamps));
memset(stamps, 0, sizeof(stamps));
}

t.c:7:28: warning: 'memset' call operates on objects of type 'struct stat' while the size is based on a different type 'struct stat *' [-Wsizeof-pointer-memaccess]
memset(stamps, 0, sizeof(stamps));
~~~~~~ ^~~~~~
t.c:7:28: note: did you mean to dereference the argument to 'sizeof' (and multiply it by the number of elements)?
memset(stamps, 0, sizeof(stamps));
^~~~~~

This patch implements the same class of warnings for bzero.

Differential Revision: https://reviews.llvm.org/D22525

rdar://problem/18963514

llvm-svn: 277787

show more ...

-Wdynamic-class-memaccess: Also warn about array types.

It looks like not warning on this was an oversight in the original
implementation of this warning.

llvm-svn: 232900

Change wording of 'memcpy' type mismatch warning and remove fixit.

As per comments following r157659.

llvm-svn: 157722

StmtProfiler: Add a null check for child statements.

llvm-svn: 151812

Add a new compiler warning, which flags anti-patterns used as the size
argument in strncat.

The warning is ignored by default since it needs more qualification.

TODO: The warning message and the n

Add a new compiler warning, which flags anti-patterns used as the size
argument in strncat.

The warning is ignored by default since it needs more qualification.

TODO: The warning message and the note are messy when
strncat is a builtin due to the macro expansion.

llvm-svn: 149524

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Extend -Wno-sizeof-array-argument to strncpy and friends.

This finds 2 bugs in chromium and 1 in hunspell, with 0 false positives.

llvm-svn: 141902

Extend memset/memcpy/memmove checking to include memcmp

llvm-svn: 136950

Rework the warning for 'memset(p, 0, sizeof(p))' where 'p' is a pointer
and the programmer intended to write 'sizeof(*p)'. There are several
elements to the new version:

1) The actual expressions ar

Rework the warning for 'memset(p, 0, sizeof(p))' where 'p' is a pointer
and the programmer intended to write 'sizeof(*p)'. There are several
elements to the new version:

1) The actual expressions are compared in order to more accurately flag
the case where the pattern that works for an array has been used, or
a '*' has been omitted.
2) Only do a loose type-based check for record types. This prevents us
from warning when we happen to be copying around chunks of data the
size of a pointer and the pointer types for the sizeof and
source/dest match.
3) Move all the diagnostics behind the runtime diagnostic filter. Not
sure this is really important for this particular diagnostic, but
almost everything else in SemaChecking.cpp does so.
4) Make the wording of the diagnostic more precise and informative. At
least to my eyes.
5) Provide highlighting for the two expressions which had the unexpected
similarity.
6) Place this diagnostic under a flag: -Wsizeof-pointer-memaccess

This uses the Stmt::Profile system for computing #1. Because of the
potential cost, this is guarded by the warning flag. I'd be interested
in feedback on how bad this is in practice; I would expect it to be
quite cheap in practice. Ideas for a cheaper / better way to do this are
also welcome.

The diagnostic wording could likely use some further wordsmithing.
Suggestions welcome here. The goals I had were to: clarify that its the
interaction of 'memset' and 'sizeof' and give more reasonable
suggestions for a resolution.

An open question is whether these diagnostics should have the note
attached for silencing by casting the dest/source pointer to void*.

llvm-svn: 133155

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Fix my test case from r133136 so that it actually represents the code
pattern found in the wild where this warning was firing.

llvm-svn: 133143

Skip both character pointers and void pointers when diagnosing bad
argument types for mem{set,cpy,move}. Character pointers, much like void
pointers, often point to generic "memory", so trying to che

Skip both character pointers and void pointers when diagnosing bad
argument types for mem{set,cpy,move}. Character pointers, much like void
pointers, often point to generic "memory", so trying to check whether
they match the type of the argument to 'sizeof' (or other checks) is
unproductive and often results in false positives.

Nico, please review; does this miss any of the bugs you were trying to
find with this warning? The array test case you had should be caught by
the array-specific sizeof warning I think.

llvm-svn: 133136

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Build fix attempt.

llvm-svn: 133039

Warn on memset(ptr, 0, sizeof(ptr)). Diagnostic wording by Jordy Rose.

llvm-svn: 132996