From 7f77eb90a54c96168d6cce8ad3a85d1454cdb80c Mon Sep 17 00:00:00 2001 From: David Majnemer Date: Sun, 15 Nov 2015 03:04:34 +0000 Subject: [PATCH] [Sema] Don't crash trying to diagnose abs called on a pointer type 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 --- .../clang/Basic/DiagnosticSemaKinds.td | 3 +++ clang/lib/Sema/SemaChecking.cpp | 13 ++++++++++++ clang/test/Sema/warn-absolute-value.c | 20 +++++++++++++++++-- 3 files changed, 34 insertions(+), 2 deletions(-) diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td index bf1101f0f4cf..d0518b985705 100644 --- a/clang/include/clang/Basic/DiagnosticSemaKinds.td +++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td @@ -67,6 +67,9 @@ def warn_wrong_absolute_value_type : Warning< "when argument is of %select{integer|floating point|complex}2 type">, InGroup; 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; def warn_infinite_recursive_function : Warning< "all paths through this function will call itself">, diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp index 5c942273314a..24940167be2f 100644 --- a/clang/lib/Sema/SemaChecking.cpp +++ b/clang/lib/Sema/SemaChecking.cpp @@ -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) diff --git a/clang/test/Sema/warn-absolute-value.c b/clang/test/Sema/warn-absolute-value.c index 70601db63a1f..109d515d3b2b 100644 --- a/clang/test/Sema/warn-absolute-value.c +++ b/clang/test/Sema/warn-absolute-value.c @@ -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}} +}