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[Sema] Don't crash trying to diagnose abs called on a pointer type

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Clang tries to figure out if a call to abs is suspicious by looking
through implicit casts to look at the underlying, implicitly converted
type.
Interestingly, C has implicit conversions from pointer-ish types like
function to less exciting types like int.  This trips up our 'abs'
checker because it doesn't know which variant of 'abs' is appropriate.

Instead, diagnose 'abs' called on function types upfront.  This sort of
thing is highly suspicious and is likely indicative of a missing
pointer dereference/function call/array index operation.

This fixes PR25532.

llvm-svn: 253156
This commit is contained in:
David Majnemer 2015-11-15 03:04:34 +00:00
parent 07fa176669
commit 7f77eb90a5
3 changed files with 34 additions and 2 deletions
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3
clang/include/clang/Basic/DiagnosticSemaKinds.td
View File

@ -67,6 +67,9 @@ def warn_wrong_absolute_value_type : Warning<
"when argument is of %select{integer|floating point|complex}2 type">,
InGroup<AbsoluteValue>;
def note_replace_abs_function : Note<"use function '%0' instead">;
def warn_pointer_abs : Warning<
"taking the absolute value of %select{pointer|function|array}0 type %1 is suspicious">,
InGroup<AbsoluteValue>;
def warn_infinite_recursive_function : Warning<
"all paths through this function will call itself">,

13
clang/lib/Sema/SemaChecking.cpp
View File

@ -5085,6 +5085,19 @@ void Sema::CheckAbsoluteValueFunction(const CallExpr *Call,
return;
}
// Taking the absolute value of a pointer is very suspicious, they probably
// wanted to index into an array, dereference a pointer, call a function, etc.
if (ArgType->isPointerType() || ArgType->canDecayToPointerType()) {
unsigned DiagType = 0;
if (ArgType->isFunctionType())
DiagType = 1;
else if (ArgType->isArrayType())
DiagType = 2;
Diag(Call->getExprLoc(), diag::warn_pointer_abs) << DiagType << ArgType;
return;
}
// std::abs has overloads which prevent most of the absolute value problems
// from occurring.
if (IsStdAbs)

20
clang/test/Sema/warn-absolute-value.c
View File

@ -1,5 +1,5 @@
// RUN: %clang_cc1 -triple i686-pc-linux-gnu -fsyntax-only -verify %s -Wabsolute-value
// RUN: %clang_cc1 -triple i686-pc-linux-gnu -fsyntax-only %s -Wabsolute-value -fdiagnostics-parseable-fixits 2>&1 | FileCheck %s
// RUN: %clang_cc1 -triple i686-pc-linux-gnu -fsyntax-only -verify %s -Wabsolute-value -Wno-int-conversion
// RUN: %clang_cc1 -triple i686-pc-linux-gnu -fsyntax-only %s -Wabsolute-value -Wno-int-conversion -fdiagnostics-parseable-fixits 2>&1 | FileCheck %s
int abs(int);
long int labs(long int);
@ -780,3 +780,19 @@ void test_unsigned_long(unsigned long x) {
// CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:9-[[@LINE-3]]:24}:""
}
long long test_array() {
return llabs((long long[]){1});
// expected-warning@-1 {{absolute value of array type}}
}
long long test_function_pointer() {
return llabs(&test_function_pointer);
// expected-warning@-1 {{absolute value of pointer type}}
}
long long test_void_pointer(void *x) {
return llabs(x);
// expected-warning@-1 {{absolute value of pointer type}}
}
long long test_function() {
return llabs(test_function);
// expected-warning@-1 {{absolute value of function type}}
}