r313677 - [Sema] Move some stuff into -Wtautological-unsigned-enum-zero-compare
Roman Lebedev via cfe-commits
cfe-commits at lists.llvm.org
Tue Sep 19 14:11:36 PDT 2017
Author: lebedevri
Date: Tue Sep 19 14:11:35 2017
New Revision: 313677
URL: http://llvm.org/viewvc/llvm-project?rev=313677&view=rev
Log:
[Sema] Move some stuff into -Wtautological-unsigned-enum-zero-compare
Summary:
As requested by Sam McCall:
> Enums (not new I guess). Typical case: if (enum < 0 || enum > MAX)
> The warning strongly suggests that the enum < 0 check has no effect
> (for enums with nonnegative ranges).
> Clang doesn't seem to optimize such checks out though, and they seem
> likely to catch bugs in some cases. Yes, only if there's UB elsewhere,
> but I assume not optimizing out these checks indicates a deliberate
> decision to stay somewhat compatible with a technically-incorrect
> mental model.
> If this is the case, should we move these to a
> -Wtautological-compare-enum subcategory?
Reviewers: rjmccall, rsmith, aaron.ballman, sammccall, bkramer, djasper
Reviewed By: aaron.ballman
Subscribers: jroelofs, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D37629
Added:
cfe/trunk/test/Sema/tautological-unsigned-enum-zero-compare.c
Modified:
cfe/trunk/include/clang/Basic/DiagnosticGroups.td
cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
cfe/trunk/lib/Sema/SemaChecking.cpp
cfe/trunk/test/Sema/compare.c
Modified: cfe/trunk/include/clang/Basic/DiagnosticGroups.td
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticGroups.td?rev=313677&r1=313676&r2=313677&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticGroups.td (original)
+++ cfe/trunk/include/clang/Basic/DiagnosticGroups.td Tue Sep 19 14:11:35 2017
@@ -429,12 +429,14 @@ def StringPlusInt : DiagGroup<"string-pl
def StringPlusChar : DiagGroup<"string-plus-char">;
def StrncatSize : DiagGroup<"strncat-size">;
def TautologicalUnsignedZeroCompare : DiagGroup<"tautological-unsigned-zero-compare">;
+def TautologicalUnsignedEnumZeroCompare : DiagGroup<"tautological-unsigned-enum-zero-compare">;
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",
[TautologicalUnsignedZeroCompare,
+ TautologicalUnsignedEnumZeroCompare,
TautologicalOutOfRangeCompare,
TautologicalPointerCompare,
TautologicalOverlapCompare,
Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=313677&r1=313676&r2=313677&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
+++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Tue Sep 19 14:11:35 2017
@@ -5906,19 +5906,26 @@ def note_typecheck_assign_const : Note<
"member function %q1 is declared const here|"
"%select{|nested }1data member %2 declared const here}0">;
+def warn_lunsigned_always_true_comparison : Warning<
+ "comparison of unsigned expression %0 is always %select{false|true}1">,
+ InGroup<TautologicalUnsignedZeroCompare>;
+def warn_runsigned_always_true_comparison : Warning<
+ "comparison of %0 unsigned expression is always %select{false|true}1">,
+ InGroup<TautologicalUnsignedZeroCompare>;
+def warn_lunsigned_enum_always_true_comparison : Warning<
+ "comparison of unsigned enum expression %0 is always %select{false|true}1">,
+ InGroup<TautologicalUnsignedEnumZeroCompare>;
+def warn_runsigned_enum_always_true_comparison : Warning<
+ "comparison of %0 unsigned enum expression is always %select{false|true}1">,
+ InGroup<TautologicalUnsignedEnumZeroCompare>;
+
def warn_mixed_sign_comparison : Warning<
"comparison of integers of different signs: %0 and %1">,
InGroup<SignCompare>, DefaultIgnore;
-def warn_lunsigned_always_true_comparison : Warning<
- "comparison of unsigned%select{| enum}2 expression %0 is always %1">,
- InGroup<TautologicalUnsignedZeroCompare>;
def warn_out_of_range_compare : Warning<
"comparison of %select{constant %0|true|false}1 with "
"%select{expression of type %2|boolean expression}3 is always "
"%select{false|true}4">, InGroup<TautologicalOutOfRangeCompare>;
-def warn_runsigned_always_true_comparison : Warning<
- "comparison of %0 unsigned%select{| enum}2 expression is always %1">,
- InGroup<TautologicalUnsignedZeroCompare>;
def warn_comparison_of_mixed_enum_types : Warning<
"comparison of two values with different enumeration types"
"%diff{ ($ and $)|}0,1">,
Modified: cfe/trunk/lib/Sema/SemaChecking.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaChecking.cpp?rev=313677&r1=313676&r2=313677&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaChecking.cpp (original)
+++ cfe/trunk/lib/Sema/SemaChecking.cpp Tue Sep 19 14:11:35 2017
@@ -8583,7 +8583,7 @@ bool CheckTautologicalComparisonWithZero
// bool values are handled by DiagnoseOutOfRangeComparison().
- BinaryOperatorKind op = E->getOpcode();
+ BinaryOperatorKind Op = E->getOpcode();
if (E->isValueDependent())
return false;
@@ -8592,22 +8592,30 @@ bool CheckTautologicalComparisonWithZero
bool Match = true;
- if (op == BO_LT && isNonBooleanUnsignedValue(LHS) && IsZero(S, RHS)) {
- S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
- << "< 0" << "false" << HasEnumType(LHS)
- << LHS->getSourceRange() << RHS->getSourceRange();
- } else if (op == BO_GE && isNonBooleanUnsignedValue(LHS) && IsZero(S, RHS)) {
- S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
- << ">= 0" << "true" << HasEnumType(LHS)
- << LHS->getSourceRange() << RHS->getSourceRange();
- } else if (op == BO_GT && isNonBooleanUnsignedValue(RHS) && IsZero(S, LHS)) {
- S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
- << "0 >" << "false" << HasEnumType(RHS)
- << LHS->getSourceRange() << RHS->getSourceRange();
- } else if (op == BO_LE && isNonBooleanUnsignedValue(RHS) && IsZero(S, LHS)) {
- S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
- << "0 <=" << "true" << HasEnumType(RHS)
- << LHS->getSourceRange() << RHS->getSourceRange();
+ if (Op == BO_LT && isNonBooleanUnsignedValue(LHS) && IsZero(S, RHS)) {
+ S.Diag(E->getOperatorLoc(),
+ HasEnumType(LHS) ? diag::warn_lunsigned_enum_always_true_comparison
+ : diag::warn_lunsigned_always_true_comparison)
+ << "< 0"
+ << "false" << LHS->getSourceRange() << RHS->getSourceRange();
+ } else if (Op == BO_GE && isNonBooleanUnsignedValue(LHS) && IsZero(S, RHS)) {
+ S.Diag(E->getOperatorLoc(),
+ HasEnumType(LHS) ? diag::warn_lunsigned_enum_always_true_comparison
+ : diag::warn_lunsigned_always_true_comparison)
+ << ">= 0"
+ << "true" << LHS->getSourceRange() << RHS->getSourceRange();
+ } else if (Op == BO_GT && isNonBooleanUnsignedValue(RHS) && IsZero(S, LHS)) {
+ S.Diag(E->getOperatorLoc(),
+ HasEnumType(RHS) ? diag::warn_runsigned_enum_always_true_comparison
+ : diag::warn_runsigned_always_true_comparison)
+ << "0 >"
+ << "false" << LHS->getSourceRange() << RHS->getSourceRange();
+ } else if (Op == BO_LE && isNonBooleanUnsignedValue(RHS) && IsZero(S, LHS)) {
+ S.Diag(E->getOperatorLoc(),
+ HasEnumType(RHS) ? diag::warn_runsigned_enum_always_true_comparison
+ : diag::warn_runsigned_always_true_comparison)
+ << "0 <="
+ << "true" << LHS->getSourceRange() << RHS->getSourceRange();
} else
Match = false;
Modified: cfe/trunk/test/Sema/compare.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/compare.c?rev=313677&r1=313676&r2=313677&view=diff
==============================================================================
--- cfe/trunk/test/Sema/compare.c (original)
+++ cfe/trunk/test/Sema/compare.c Tue Sep 19 14:11:35 2017
@@ -308,8 +308,59 @@ int rdar8414119_bar(unsigned x) {
int rdar8511238() {
enum A { A_foo, A_bar };
enum A a;
+
+ if (a == 0)
+ return 0;
+ if (a != 0)
+ return 0;
if (a < 0) // expected-warning {{comparison of unsigned enum expression < 0 is always false}}
- return 0;
+ return 0;
+ if (a <= 0)
+ return 0;
+ if (a > 0)
+ return 0;
+ if (a >= 0) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
+ return 0;
+
+ if (0 == a)
+ return 0;
+ if (0 != a)
+ return 0;
+ if (0 < a)
+ return 0;
+ if (0 <= a) // expected-warning {{comparison of 0 <= unsigned enum expression is always true}}
+ return 0;
+ if (0 > a) // expected-warning {{comparison of 0 > unsigned enum expression is always false}}
+ return 0;
+ if (0 >= a)
+ return 0;
+
+ if (a == 0U)
+ return 0;
+ if (a != 0U)
+ return 0;
+ if (a < 0U) // expected-warning {{comparison of unsigned enum expression < 0 is always false}}
+ return 0;
+ if (a <= 0U)
+ return 0;
+ if (a > 0U)
+ return 0;
+ if (a >= 0U) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
+ return 0;
+
+ if (0U == a)
+ return 0;
+ if (0U != a)
+ return 0;
+ if (0U < a)
+ return 0;
+ if (0U <= a) // expected-warning {{comparison of 0 <= unsigned enum expression is always true}}
+ return 0;
+ if (0U > a) // expected-warning {{comparison of 0 > unsigned enum expression is always false}}
+ return 0;
+ if (0U >= a)
+ return 0;
+
return 20;
}
Added: cfe/trunk/test/Sema/tautological-unsigned-enum-zero-compare.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/tautological-unsigned-enum-zero-compare.c?rev=313677&view=auto
==============================================================================
--- cfe/trunk/test/Sema/tautological-unsigned-enum-zero-compare.c (added)
+++ cfe/trunk/test/Sema/tautological-unsigned-enum-zero-compare.c Tue Sep 19 14:11:35 2017
@@ -0,0 +1,46 @@
+// RUN: %clang_cc1 -fsyntax-only -DTEST -verify %s
+// RUN: %clang_cc1 -fsyntax-only -Wno-tautological-unsigned-enum-zero-compare -verify %s
+
+int main() {
+ enum A { A_foo, A_bar };
+ enum A a;
+
+#ifdef TEST
+ if (a < 0) // expected-warning {{comparison of unsigned enum expression < 0 is always false}}
+ return 0;
+ if (a >= 0) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
+ return 0;
+ if (0 <= a) // expected-warning {{comparison of 0 <= unsigned enum expression is always true}}
+ return 0;
+ if (0 > a) // expected-warning {{comparison of 0 > unsigned enum expression is always false}}
+ return 0;
+ if (a < 0U) // expected-warning {{comparison of unsigned enum expression < 0 is always false}}
+ return 0;
+ if (a >= 0U) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
+ return 0;
+ if (0U <= a) // expected-warning {{comparison of 0 <= unsigned enum expression is always true}}
+ return 0;
+ if (0U > a) // expected-warning {{comparison of 0 > unsigned enum expression is always false}}
+ return 0;
+#else
+ // expected-no-diagnostics
+ if (a < 0)
+ return 0;
+ if (a >= 0)
+ return 0;
+ if (0 <= a)
+ return 0;
+ if (0 > a)
+ return 0;
+ if (a < 0U)
+ return 0;
+ if (a >= 0U)
+ return 0;
+ if (0U <= a)
+ return 0;
+ if (0U > a)
+ return 0;
+#endif
+
+ return 1;
+}
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