C89 allowed a type specifier to be elided with the resulting type being
int, aka implicit int behavior. This feature was subsequently removed
in C99 without a deprecation period, so implementations continued to
support the feature. Now, as with implicit function declarations, is a
good time to reevaluate the need for this support.
This patch allows -Wimplicit-int to issue warnings in C89 mode (off by
default), defaults the warning to an error in C99 through C17, and
disables support for the feature entirely in C2x. It also removes a
warning about missing declaration specifiers that really was just an
implicit int warning in disguise and other minor related cleanups.
C89 had a questionable feature where the compiler would implicitly
declare a function that the user called but was never previously
declared. The resulting function would be globally declared as
extern int func(); -- a function without a prototype which accepts zero
or more arguments.
C99 removed support for this questionable feature due to severe
security concerns. However, there was no deprecation period; C89 had
the feature, C99 didn't. So Clang (and GCC) both supported the
functionality as an extension in C99 and later modes.
C2x no longer supports that function signature as it now requires all
functions to have a prototype, and given the known security issues with
the feature, continuing to support it as an extension is not tenable.
This patch changes the diagnostic behavior for the
-Wimplicit-function-declaration warning group depending on the language
mode in effect. We continue to warn by default in C89 mode (due to the
feature being dangerous to use). However, because this feature will not
be supported in C2x mode, we've diagnosed it as being invalid for so
long, the security concerns with the feature, and the trivial
workaround for users (declare the function), we now default the
extension warning to an error in C99-C17 mode. This still gives users
an easy workaround if they are extensively using the extension in those
modes (they can disable the warning or use -Wno-error to downgrade the
error), but the new diagnostic makes it more clear that this feature is
not supported and should be avoided. In C2x mode, we no longer allow an
implicit function to be defined and treat the situation the same as any
other lookup failure.
Differential Revision: https://reviews.llvm.org/D122983
A significant number of our tests in C accidentally use functions
without prototypes. This patch converts the function signatures to have
a prototype for the situations where the test is not specific to K&R C
declarations. e.g.,
void func();
becomes
void func(void);
This is the third batch of tests being updated (there are a significant
number of other tests left to be updated).
The dependency mechanism for C has been implemented, and we have rolled out
this to all internal users, didn't see crashy issues, we consider it is stable
enough.
Differential Revision: https://reviews.llvm.org/D89046
D54902 removed CallExpr::setNumArgs in preparation of tail-allocating the
arguments of CallExpr. It did this by allocating storage for
max(number of arguments, number of parameters in the prototype). The
temporarily nulled arguments however causes issues in BuildResolvedCallExpr
when typo correction is done just after the creation of the call expression.
This was unfortunately missed by the tests /:
To fix this, delay setting the number of arguments to
max(number of arguments, number of parameters in the prototype) until we are
ready for it. It would be nice to have this encapsulated in CallExpr but this
is the best I can come up with under the constraint that we cannot add
anything the CallExpr.
Fixes PR40286.
Differential Revision: https://reviews.llvm.org/D57948
Reviewed By: aaron.ballman
llvm-svn: 354035
NumTypos guard value ~0U doesn't prevent from creating new delayed typos. When
you create new delayed typos during typo correction, value ~0U wraps around to
0. When NumTypos is 0 we can miss some typos and treat an expression as it can
be typo-corrected. But if the expression is still invalid after correction, we
can get stuck in infinite loop trying to correct it.
Fix by not using value ~0U so that NumTypos correctly reflects the number of
typos.
rdar://problem/38642201
Reviewers: arphaman, majnemer, rsmith
Reviewed By: rsmith
Subscribers: rsmith, nicholas, cfe-commits
Differential Revision: https://reviews.llvm.org/D47341
llvm-svn: 335638
In C typos in arguments in a call of an overloadable function lead
to a failure of construction of CallExpr and following recovery does
not handle created delayed typos. This causes an assertion fail in
Sema::~Sema since Sema::DelayedTypos remains not empty.
The patch fixes that behavior by handling a call with arguments
having dependant types in the way that C++ does.
Differential Revision: https://reviews.llvm.org/D31764
Patch by Dmitry Borisenkov!
llvm-svn: 302435
ActOnBinOp corrects delayed typos when in C mode; don't correct them in that
case. Fixes PR26700.
Differential Revision: http://reviews.llvm.org/D20490
llvm-svn: 272587
The problem is that the arguments are of TheCall are reset later
to the ones in Args, making TypoExpr put back. Some TypoExpr that have
already been diagnosed and will assert later in Sema::getTypoExprState
llvm-svn: 245560
Regular function calls (such as to cabs()) run into the same problem
with handling dependent exprs, not just builtins with custom type
checking.
Fixes PR23775.
llvm-svn: 240443
In particular, remove the OpaqueExpr transformation from r225389 and
move the correction of the conditional from CheckConditionalOperands to
ActOnConditionalOp before the OpaqueExpr is created. This fixes the
typo correction behavior in C code that uses the GNU extension for a
binary ?: (without an expression between the "?" and the ":").
llvm-svn: 227220
transform.
Also diagnose typos in the initializer of an invalid C++ declaration.
Both issues were hit using the same line of test code, depending on
whether the code was treated as C or C++.
Fixes PR22092.
llvm-svn: 225389
Aaron Ballman