r210372 - Add -Wtautological-undefined-compare and -Wundefined-bool-conversion warnings
Kostya Serebryany
kcc at google.com
Mon Jun 9 01:07:36 PDT 2014
Meanwhile, all our bots are red due to this commit.
On Mon, Jun 9, 2014 at 3:59 AM, Gabriel Dos Reis <
gdr at integrable-solutions.net> wrote:
>
>
>
> On Sun, Jun 8, 2014 at 4:20 PM, NAKAMURA Takumi <geek4civic at gmail.com>
> wrote:
>
>> We see warnings in the llvm/clang tree. Shall we honor them?
>>
>> /home/tnakamura/fio/ninja/llvm-project/llvm/lib/IR/AsmWriter.cpp:2159:8:
>> error: 'this' pointer cannot be null in well-defined C++ code; pointer
>> may be assumed always converted to true
>> [-Werror,-Wundefined-bool-conversion]
>> if (!this) {
>> ~^~~~
>> llvm/lib/IR/AsmWriter.cpp:2175:8: error: 'this' pointer cannot be null
>> in well-defined C++ code; pointer may be assumed always converted to
>> true [-Werror,-Wundefined-bool-conversion]
>> if (!this) {
>> ~^~~~
>>
>> clang/lib/AST/StmtPrinter.cpp:2028:7: error: 'this' pointer cannot be
>> null in well-defined C++ code; comparison may be assumed to always
>> evaluate to false [-Werror,-Wtautological-undefined-compare]
>> if (this == nullptr) {
>> ^~~~ ~~~~~~~
>>
>
> Interesting. Looks like potentially a source of bug in the existing code
> :-)
>
> -- Gaby
>
>
>
>>
>> 2014-06-07 6:39 GMT+09:00 Richard Trieu <rtrieu at google.com>:
>> > Author: rtrieu
>> > Date: Fri Jun 6 16:39:26 2014
>> > New Revision: 210372
>> >
>> > URL: http://llvm.org/viewvc/llvm-project?rev=210372&view=rev
>> > Log:
>> > Add -Wtautological-undefined-compare and -Wundefined-bool-conversion
>> warnings
>> > to detect underfined behavior involving pointers.
>> >
>> > Added:
>> > cfe/trunk/test/SemaCXX/warn-tautological-undefined-compare.cpp
>> > cfe/trunk/test/SemaCXX/warn-undefined-bool-conversion.cpp
>> > Modified:
>> > cfe/trunk/include/clang/Basic/DiagnosticGroups.td
>> > cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
>> > cfe/trunk/lib/Sema/SemaChecking.cpp
>> > cfe/trunk/test/Analysis/inlining/path-notes.cpp
>> > cfe/trunk/test/Analysis/misc-ps-region-store.cpp
>> > cfe/trunk/test/Analysis/reference.cpp
>> > cfe/trunk/test/Analysis/stack-addr-ps.cpp
>> >
>> > Modified: cfe/trunk/include/clang/Basic/DiagnosticGroups.td
>> > URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticGroups.td?rev=210372&r1=210371&r2=210372&view=diff
>> >
>> ==============================================================================
>> > --- cfe/trunk/include/clang/Basic/DiagnosticGroups.td (original)
>> > +++ cfe/trunk/include/clang/Basic/DiagnosticGroups.td Fri Jun 6
>> 16:39:26 2014
>> > @@ -38,7 +38,9 @@ def LiteralConversion : DiagGroup<"liter
>> > def StringConversion : DiagGroup<"string-conversion">;
>> > def SignConversion : DiagGroup<"sign-conversion">;
>> > def PointerBoolConversion : DiagGroup<"pointer-bool-conversion">;
>> > -def BoolConversion : DiagGroup<"bool-conversion", [
>> PointerBoolConversion ] >;
>> > +def UndefinedBoolConversion : DiagGroup<"undefined-bool-conversion">;
>> > +def BoolConversion : DiagGroup<"bool-conversion",
>> [PointerBoolConversion,
>> > +
>> UndefinedBoolConversion]>;
>> > def IntConversion : DiagGroup<"int-conversion">;
>> > def EnumConversion : DiagGroup<"enum-conversion">;
>> > def FloatConversion : DiagGroup<"float-conversion">;
>> > @@ -298,10 +300,12 @@ def StrncatSize : DiagGroup<"strncat-siz
>> > def TautologicalOutOfRangeCompare :
>> DiagGroup<"tautological-constant-out-of-range-compare">;
>> > def TautologicalPointerCompare :
>> DiagGroup<"tautological-pointer-compare">;
>> > def TautologicalOverlapCompare :
>> DiagGroup<"tautological-overlap-compare">;
>> > +def TautologicalUndefinedCompare :
>> DiagGroup<"tautological-undefined-compare">;
>> > def TautologicalCompare : DiagGroup<"tautological-compare",
>> > [TautologicalOutOfRangeCompare,
>> > TautologicalPointerCompare,
>> > - TautologicalOverlapCompare]>;
>> > + TautologicalOverlapCompare,
>> > + TautologicalUndefinedCompare]>;
>> > def HeaderHygiene : DiagGroup<"header-hygiene">;
>> > def DuplicateDeclSpecifier : DiagGroup<"duplicate-decl-specifier">;
>> > def CompareDistinctPointerType :
>> DiagGroup<"compare-distinct-pointer-types">;
>> >
>> > Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
>> > URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=210372&r1=210371&r2=210372&view=diff
>> >
>> ==============================================================================
>> > --- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
>> > +++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Fri Jun 6
>> 16:39:26 2014
>> > @@ -2400,10 +2400,27 @@ def warn_impcast_pointer_to_bool : Warni
>> > "address of%select{| function| array}0 '%1' will always evaluate
>> to "
>> > "'true'">,
>> > InGroup<PointerBoolConversion>;
>> > +def warn_this_bool_conversion : Warning<
>> > + "'this' pointer cannot be null in well-defined C++ code; pointer may
>> be "
>> > + "assumed always converted to true">,
>> InGroup<UndefinedBoolConversion>;
>> > +def warn_address_of_reference_bool_conversion : Warning<
>> > + "reference cannot be bound to dereferenced null pointer in
>> well-defined C++ "
>> > + "code; pointer may be assumed always converted to true">,
>> > + InGroup<UndefinedBoolConversion>;
>> > +
>> > def warn_null_pointer_compare : Warning<
>> > "comparison of %select{address of|function|array}0 '%1'
>> %select{not |}2"
>> > "equal to a null pointer is always %select{true|false}2">,
>> > InGroup<TautologicalPointerCompare>;
>> > +def warn_this_null_compare : Warning<
>> > + "'this' pointer cannot be null in well-defined C++ code; comparison
>> may be "
>> > + "assumed to always evaluate to %select{true|false}0">,
>> > + InGroup<TautologicalUndefinedCompare>;
>> > +def warn_address_of_reference_null_compare : Warning<
>> > + "reference cannot be bound to dereferenced null pointer in
>> well-defined C++ "
>> > + "code; comparison may be assumed to always evaluate to "
>> > + "%select{true|false}0">,
>> > + InGroup<TautologicalUndefinedCompare>;
>> >
>> > def note_function_warning_silence : Note<
>> > "prefix with the address-of operator to silence this warning">;
>> >
>> > Modified: cfe/trunk/lib/Sema/SemaChecking.cpp
>> > URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaChecking.cpp?rev=210372&r1=210371&r2=210372&view=diff
>> >
>> ==============================================================================
>> > --- cfe/trunk/lib/Sema/SemaChecking.cpp (original)
>> > +++ cfe/trunk/lib/Sema/SemaChecking.cpp Fri Jun 6 16:39:26 2014
>> > @@ -6189,6 +6189,13 @@ void Sema::DiagnoseAlwaysNonNullPointer(
>> >
>> > const bool IsCompare = NullKind != Expr::NPCK_NotNull;
>> >
>> > + if (isa<CXXThisExpr>(E)) {
>> > + unsigned DiagID = IsCompare ? diag::warn_this_null_compare
>> > + : diag::warn_this_bool_conversion;
>> > + Diag(E->getExprLoc(), DiagID) << E->getSourceRange() << Range <<
>> IsEqual;
>> > + return;
>> > + }
>> > +
>> > bool IsAddressOf = false;
>> >
>> > if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
>> > @@ -6218,9 +6225,14 @@ void Sema::DiagnoseAlwaysNonNullPointer(
>> > // Address of function is used to silence the function warning.
>> > if (IsFunction)
>> > return;
>> > - // Address of reference can be null.
>> > - if (T->isReferenceType())
>> > +
>> > + if (T->isReferenceType()) {
>> > + unsigned DiagID = IsCompare
>> > + ?
>> diag::warn_address_of_reference_null_compare
>> > + :
>> diag::warn_address_of_reference_bool_conversion;
>> > + Diag(E->getExprLoc(), DiagID) << E->getSourceRange() << Range <<
>> IsEqual;
>> > return;
>> > + }
>> > }
>> >
>> > // Found nothing.
>> >
>> > Modified: cfe/trunk/test/Analysis/inlining/path-notes.cpp
>> > URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Analysis/inlining/path-notes.cpp?rev=210372&r1=210371&r2=210372&view=diff
>> >
>> ==============================================================================
>> > --- cfe/trunk/test/Analysis/inlining/path-notes.cpp (original)
>> > +++ cfe/trunk/test/Analysis/inlining/path-notes.cpp Fri Jun 6 16:39:26
>> 2014
>> > @@ -1,5 +1,5 @@
>> > -// RUN: %clang_cc1 -analyze -analyzer-checker=core
>> -analyzer-output=text -analyzer-config c++-inlining=destructors -std=c++11
>> -verify %s
>> > -// RUN: %clang_cc1 -analyze -analyzer-checker=core
>> -analyzer-output=plist-multi-file -analyzer-config c++-inlining=destructors
>> -std=c++11 -analyzer-config path-diagnostics-alternate=false %s -o %t.plist
>> > +// RUN: %clang_cc1 -analyze -analyzer-checker=core
>> -analyzer-output=text -analyzer-config c++-inlining=destructors -std=c++11
>> -verify -Wno-tautological-undefined-compare %s
>> > +// RUN: %clang_cc1 -analyze -analyzer-checker=core
>> -analyzer-output=plist-multi-file -analyzer-config c++-inlining=destructors
>> -std=c++11 -analyzer-config path-diagnostics-alternate=false %s -o %t.plist
>> -Wno-tautological-undefined-compare
>> > // RUN: FileCheck --input-file=%t.plist %s
>> >
>> > class Foo {
>> >
>> > Modified: cfe/trunk/test/Analysis/misc-ps-region-store.cpp
>> > URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Analysis/misc-ps-region-store.cpp?rev=210372&r1=210371&r2=210372&view=diff
>> >
>> ==============================================================================
>> > --- cfe/trunk/test/Analysis/misc-ps-region-store.cpp (original)
>> > +++ cfe/trunk/test/Analysis/misc-ps-region-store.cpp Fri Jun 6
>> 16:39:26 2014
>> > @@ -1,5 +1,5 @@
>> > -// RUN: %clang_cc1 -triple i386-apple-darwin9 -analyze
>> -analyzer-checker=core,alpha.core,debug.ExprInspection
>> -analyzer-store=region -verify -fblocks -analyzer-opt-analyze-nested-blocks
>> %s -fexceptions -fcxx-exceptions
>> > -// RUN: %clang_cc1 -triple x86_64-apple-darwin9 -analyze
>> -analyzer-checker=core,alpha.core,debug.ExprInspection
>> -analyzer-store=region -verify -fblocks -analyzer-opt-analyze-nested-blocks
>> %s -fexceptions -fcxx-exceptions
>> > +// RUN: %clang_cc1 -triple i386-apple-darwin9 -analyze
>> -analyzer-checker=core,alpha.core,debug.ExprInspection
>> -analyzer-store=region -verify -fblocks -analyzer-opt-analyze-nested-blocks
>> %s -fexceptions -fcxx-exceptions -Wno-tautological-undefined-compare
>> > +// RUN: %clang_cc1 -triple x86_64-apple-darwin9 -analyze
>> -analyzer-checker=core,alpha.core,debug.ExprInspection
>> -analyzer-store=region -verify -fblocks -analyzer-opt-analyze-nested-blocks
>> %s -fexceptions -fcxx-exceptions -Wno-tautological-undefined-compare
>> >
>> > void clang_analyzer_warnIfReached();
>> >
>> >
>> > Modified: cfe/trunk/test/Analysis/reference.cpp
>> > URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Analysis/reference.cpp?rev=210372&r1=210371&r2=210372&view=diff
>> >
>> ==============================================================================
>> > --- cfe/trunk/test/Analysis/reference.cpp (original)
>> > +++ cfe/trunk/test/Analysis/reference.cpp Fri Jun 6 16:39:26 2014
>> > @@ -1,4 +1,4 @@
>> > -// RUN: %clang_cc1 -analyze
>> -analyzer-checker=core,alpha.core,debug.ExprInspection
>> -analyzer-store=region -analyzer-constraints=range -verify
>> -Wno-null-dereference %s
>> > +// RUN: %clang_cc1 -analyze
>> -analyzer-checker=core,alpha.core,debug.ExprInspection
>> -analyzer-store=region -analyzer-constraints=range -verify
>> -Wno-null-dereference -Wno-tautological-undefined-compare %s
>> >
>> > void clang_analyzer_eval(bool);
>> >
>> >
>> > Modified: cfe/trunk/test/Analysis/stack-addr-ps.cpp
>> > URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Analysis/stack-addr-ps.cpp?rev=210372&r1=210371&r2=210372&view=diff
>> >
>> ==============================================================================
>> > --- cfe/trunk/test/Analysis/stack-addr-ps.cpp (original)
>> > +++ cfe/trunk/test/Analysis/stack-addr-ps.cpp Fri Jun 6 16:39:26 2014
>> > @@ -1,4 +1,4 @@
>> > -// RUN: %clang_cc1 -analyze -analyzer-checker=core
>> -analyzer-store=region -verify %s
>> > +// RUN: %clang_cc1 -analyze -analyzer-checker=core
>> -analyzer-store=region -verify %s -Wno-undefined-bool-conversion
>> >
>> > typedef __INTPTR_TYPE__ intptr_t;
>> >
>> >
>> > Added: cfe/trunk/test/SemaCXX/warn-tautological-undefined-compare.cpp
>> > URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/warn-tautological-undefined-compare.cpp?rev=210372&view=auto
>> >
>> ==============================================================================
>> > --- cfe/trunk/test/SemaCXX/warn-tautological-undefined-compare.cpp
>> (added)
>> > +++ cfe/trunk/test/SemaCXX/warn-tautological-undefined-compare.cpp Fri
>> Jun 6 16:39:26 2014
>> > @@ -0,0 +1,34 @@
>> > +// RUN: %clang_cc1 -fsyntax-only -verify %s
>> > +// RUN: %clang_cc1 -fsyntax-only -verify
>> -Wtautological-undefined-compare %s
>> > +// RUN: %clang_cc1 -fsyntax-only -verify -Wno-tautological-compare
>> -Wtautological-undefined-compare %s
>> > +// RUN: %clang_cc1 -fsyntax-only -verify -Wtautological-compare %s
>> > +
>> > +void test1(int &x) {
>> > + if (x == 1) { }
>> > + if (&x == 0) { }
>> > + // expected-warning at -1{{reference cannot be bound to dereferenced
>> null pointer in well-defined C++ code; comparison may be assumed to always
>> evaluate to false}}
>> > + if (&x != 0) { }
>> > + // expected-warning at -1{{reference cannot be bound to dereferenced
>> null pointer in well-defined C++ code; comparison may be assumed to always
>> evaluate to true}}
>> > +}
>> > +
>> > +class test2 {
>> > + test2() : x(y) {}
>> > +
>> > + void foo() {
>> > + if (this == 0) { }
>> > + // expected-warning at -1{{'this' pointer cannot be null in
>> well-defined C++ code; comparison may be assumed to always evaluate to
>> false}}
>> > + if (this != 0) { }
>> > + // expected-warning at -1{{'this' pointer cannot be null in
>> well-defined C++ code; comparison may be assumed to always evaluate to
>> true}}
>> > + }
>> > +
>> > + void bar() {
>> > + if (x == 1) { }
>> > + if (&x == 0) { }
>> > + // expected-warning at -1{{reference cannot be bound to dereferenced
>> null pointer in well-defined C++ code; comparison may be assumed to always
>> evaluate to false}}
>> > + if (&x != 0) { }
>> > + // expected-warning at -1{{reference cannot be bound to dereferenced
>> null pointer in well-defined C++ code; comparison may be assumed to always
>> evaluate to true}}
>> > + }
>> > +
>> > + int &x;
>> > + int y;
>> > +};
>> >
>> > Added: cfe/trunk/test/SemaCXX/warn-undefined-bool-conversion.cpp
>> > URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/warn-undefined-bool-conversion.cpp?rev=210372&view=auto
>> >
>> ==============================================================================
>> > --- cfe/trunk/test/SemaCXX/warn-undefined-bool-conversion.cpp (added)
>> > +++ cfe/trunk/test/SemaCXX/warn-undefined-bool-conversion.cpp Fri Jun
>> 6 16:39:26 2014
>> > @@ -0,0 +1,37 @@
>> > +// RUN: %clang_cc1 -fsyntax-only -verify %s
>> > +// RUN: %clang_cc1 -fsyntax-only -verify -Wundefined-bool-conversion %s
>> > +// RUN: %clang_cc1 -fsyntax-only -verify -Wno-bool-conversion
>> -Wundefined-bool-conversion %s
>> > +// RUN: %clang_cc1 -fsyntax-only -verify -Wbool-conversion %s
>> > +
>> > +void test1(int &x) {
>> > + if (x == 1) { }
>> > + if (&x) { }
>> > + // expected-warning at -1{{reference cannot be bound to dereferenced
>> null pointer in well-defined C++ code; pointer may be assumed always
>> converted to true}}
>> > +
>> > + if (!&x) { }
>> > + // expected-warning at -1{{reference cannot be bound to dereferenced
>> null pointer in well-defined C++ code; pointer may be assumed always
>> converted to true}}
>> > +}
>> > +
>> > +class test2 {
>> > + test2() : x(y) {}
>> > +
>> > + void foo() {
>> > + if (this) { }
>> > + // expected-warning at -1{{'this' pointer cannot be null in
>> well-defined C++ code; pointer may be assumed always converted to true}}
>> > +
>> > + if (!this) { }
>> > + // expected-warning at -1{{'this' pointer cannot be null in
>> well-defined C++ code; pointer may be assumed always converted to true}}
>> > + }
>> > +
>> > + void bar() {
>> > + if (x == 1) { }
>> > + if (&x) { }
>> > + // expected-warning at -1{{reference cannot be bound to dereferenced
>> null pointer in well-defined C++ code; pointer may be assumed always
>> converted to true}}
>> > +
>> > + if (!&x) { }
>> > + // expected-warning at -1{{reference cannot be bound to dereferenced
>> null pointer in well-defined C++ code; pointer may be assumed always
>> converted to true}}
>> > + }
>> > +
>> > + int &x;
>> > + int y;
>> > +};
>> >
>> >
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