Index: clang-tools-extra/trunk/clang-tidy/bugprone/BugproneTidyModule.cpp =================================================================== --- clang-tools-extra/trunk/clang-tidy/bugprone/BugproneTidyModule.cpp +++ clang-tools-extra/trunk/clang-tidy/bugprone/BugproneTidyModule.cpp @@ -10,6 +10,7 @@ #include "../ClangTidy.h" #include "../ClangTidyModule.h" #include "../ClangTidyModuleRegistry.h" +#include "IntegerDivisionCheck.h" #include "SuspiciousMemsetUsageCheck.h" #include "UndefinedMemoryManipulationCheck.h" @@ -20,6 +21,8 @@ class BugproneModule : public ClangTidyModule { public: void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override { + CheckFactories.registerCheck( + "bugprone-integer-division"); CheckFactories.registerCheck( "bugprone-suspicious-memset-usage"); CheckFactories.registerCheck( Index: clang-tools-extra/trunk/clang-tidy/bugprone/CMakeLists.txt =================================================================== --- clang-tools-extra/trunk/clang-tidy/bugprone/CMakeLists.txt +++ clang-tools-extra/trunk/clang-tidy/bugprone/CMakeLists.txt @@ -2,6 +2,7 @@ add_clang_library(clangTidyBugproneModule BugproneTidyModule.cpp + IntegerDivisionCheck.cpp SuspiciousMemsetUsageCheck.cpp UndefinedMemoryManipulationCheck.cpp Index: clang-tools-extra/trunk/clang-tidy/bugprone/IntegerDivisionCheck.h =================================================================== --- clang-tools-extra/trunk/clang-tidy/bugprone/IntegerDivisionCheck.h +++ clang-tools-extra/trunk/clang-tidy/bugprone/IntegerDivisionCheck.h @@ -0,0 +1,36 @@ +//===--- IntegerDivisionCheck.h - clang-tidy---------------------*- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// + +#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_INTEGER_DIVISION_H +#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_INTEGER_DIVISION_H + +#include "../ClangTidy.h" + +namespace clang { +namespace tidy { +namespace bugprone { + +/// Finds cases where integer division in a floating point context is likely to +/// cause unintended loss of precision. +/// +/// For the user-facing documentation see: +/// http://clang.llvm.org/extra/clang-tidy/checks/bugprone-integer-division.html +class IntegerDivisionCheck : public ClangTidyCheck { +public: + IntegerDivisionCheck(StringRef Name, ClangTidyContext *Context) + : ClangTidyCheck(Name, Context) {} + void registerMatchers(ast_matchers::MatchFinder *Finder) override; + void check(const ast_matchers::MatchFinder::MatchResult &Result) override; +}; + +} // namespace bugprone +} // namespace tidy +} // namespace clang + +#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_INTEGER_DIVISION_H Index: clang-tools-extra/trunk/clang-tidy/bugprone/IntegerDivisionCheck.cpp =================================================================== --- clang-tools-extra/trunk/clang-tidy/bugprone/IntegerDivisionCheck.cpp +++ clang-tools-extra/trunk/clang-tidy/bugprone/IntegerDivisionCheck.cpp @@ -0,0 +1,57 @@ +//===--- IntegerDivisionCheck.cpp - clang-tidy-----------------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// + +#include "IntegerDivisionCheck.h" +#include "clang/AST/ASTContext.h" +#include "clang/ASTMatchers/ASTMatchFinder.h" + +using namespace clang::ast_matchers; + +namespace clang { +namespace tidy { +namespace bugprone { + +void IntegerDivisionCheck::registerMatchers(MatchFinder *Finder) { + const auto IntType = hasType(isInteger()); + + const auto BinaryOperators = binaryOperator(anyOf( + hasOperatorName("%"), hasOperatorName("<<"), hasOperatorName(">>"), + hasOperatorName("<<"), hasOperatorName("^"), hasOperatorName("|"), + hasOperatorName("&"), hasOperatorName("||"), hasOperatorName("&&"), + hasOperatorName("<"), hasOperatorName(">"), hasOperatorName("<="), + hasOperatorName(">="), hasOperatorName("=="), hasOperatorName("!="))); + + const auto UnaryOperators = + unaryOperator(anyOf(hasOperatorName("~"), hasOperatorName("!"))); + + const auto Exceptions = + anyOf(BinaryOperators, conditionalOperator(), binaryConditionalOperator(), + callExpr(IntType), explicitCastExpr(IntType), UnaryOperators); + + Finder->addMatcher( + binaryOperator( + hasOperatorName("/"), hasLHS(expr(IntType)), hasRHS(expr(IntType)), + hasAncestor( + castExpr(hasCastKind(CK_IntegralToFloating)).bind("FloatCast")), + unless(hasAncestor( + expr(Exceptions, + hasAncestor(castExpr(equalsBoundNode("FloatCast"))))))) + .bind("IntDiv"), + this); +} + +void IntegerDivisionCheck::check(const MatchFinder::MatchResult &Result) { + const auto *IntDiv = Result.Nodes.getNodeAs("IntDiv"); + diag(IntDiv->getLocStart(), "result of integer division used in a floating " + "point context; possible loss of precision"); +} + +} // namespace bugprone +} // namespace tidy +} // namespace clang Index: clang-tools-extra/trunk/docs/ReleaseNotes.rst =================================================================== --- clang-tools-extra/trunk/docs/ReleaseNotes.rst +++ clang-tools-extra/trunk/docs/ReleaseNotes.rst @@ -70,6 +70,12 @@ ``AllowConditionalIntegerCasts`` -> ``AllowIntegerConditions``, ``AllowConditionalPointerCasts`` -> ``AllowPointerConditions``. +- New `bugprone-integer-division + `_ check + + Finds cases where integer division in a floating point context is likely to + cause unintended loss of precision. + - New `readability-static-accessed-through-instance `_ check Index: clang-tools-extra/trunk/docs/clang-tidy/checks/bugprone-integer-division.rst =================================================================== --- clang-tools-extra/trunk/docs/clang-tidy/checks/bugprone-integer-division.rst +++ clang-tools-extra/trunk/docs/clang-tidy/checks/bugprone-integer-division.rst @@ -0,0 +1,39 @@ +.. title:: clang-tidy - bugprone-integer-division + +bugprone-integer-division +========================= + +Finds cases where integer division in a floating point context is likely to +cause unintended loss of precision. + +No reports are made if divisions are part of the following expressions: + +- operands of operators expecting integral or bool types, +- call expressions of integral or bool types, and +- explicit cast expressions to integral or bool types, + +as these are interpreted as signs of deliberateness from the programmer. + +Examples: + +.. code-block:: c++ + + float floatFunc(float); + int intFunc(int); + double d; + int i = 42; + + // Warn, floating-point values expected. + d = 32 * 8 / (2 + i); + d = 8 * floatFunc(1 + 7 / 2); + d = i / (1 << 4); + + // OK, no integer division. + d = 32 * 8.0 / (2 + i); + d = 8 * floatFunc(1 + 7.0 / 2); + d = (double)i / (1 << 4); + + // OK, there are signs of deliberateness. + d = 1 << (i / 2); + d = 9 + intFunc(6 * i / 32); + d = (int)(i / 32) - 8; Index: clang-tools-extra/trunk/docs/clang-tidy/checks/list.rst =================================================================== --- clang-tools-extra/trunk/docs/clang-tidy/checks/list.rst +++ clang-tools-extra/trunk/docs/clang-tidy/checks/list.rst @@ -9,6 +9,7 @@ android-cloexec-open android-cloexec-socket boost-use-to-string + bugprone-integer-division bugprone-suspicious-memset-usage bugprone-undefined-memory-manipulation cert-dcl03-c (redirects to misc-static-assert) Index: clang-tools-extra/trunk/test/clang-tidy/bugprone-integer-division.cpp =================================================================== --- clang-tools-extra/trunk/test/clang-tidy/bugprone-integer-division.cpp +++ clang-tools-extra/trunk/test/clang-tidy/bugprone-integer-division.cpp @@ -0,0 +1,130 @@ +// RUN: %check_clang_tidy %s bugprone-integer-division %t + +// Functions expecting a floating-point parameter. +void floatArg(float x) {} +void doubleArg(double x) {} +void longDoubleArg(long double x) {} + +// Functions expected to return a floating-point value. +float singleDiv() { + int x = -5; + int y = 2; + return x/y; +// CHECK-MESSAGES: :[[@LINE-1]]:10: warning: result of integer division used in +} + +double wrongOrder(int x, int y) { + return x/y/0.1; +// CHECK-MESSAGES: :[[@LINE-1]]:10: warning: result of integer division used in +} + +long double rightOrder(int x, int y) { + return 0.1/x/y; // OK +} + +// Typical mathematical functions. +float sin(float); +double acos(double); +long double tanh(long double); + +namespace std { + using ::sin; +} + +template +void intDivSin(T x) { + sin(x); +} + +int intFunc(int); + +struct X { + int n; + void m() { + sin(n / 3); +// CHECK-MESSAGES: :[[@LINE-1]]:9: warning: result of integer division used in + } +}; + +void integerDivision() { + char a = 2; + short b = -5; + int c = 9784; + enum third { x, y, z=2 }; + third d = z; + char e[] = {'a', 'b', 'c'}; + char f = *(e + 1 / a); + bool g = 1; + + sin(1 + c / (2 + 2)); +// CHECK-MESSAGES: :[[@LINE-1]]:11: warning: result of integer division used in + sin(c / (1 + .5)); + sin((c + .5) / 3); + + sin(intFunc(3) / 5); +// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: result of integer division used in + acos(2 / intFunc(7)); +// CHECK-MESSAGES: :[[@LINE-1]]:8: warning: result of integer division used in + + floatArg(1 + 2 / 3); +// CHECK-MESSAGES: :[[@LINE-1]]:16: warning: result of integer division used in + sin(1 + 2 / 3); +// CHECK-MESSAGES: :[[@LINE-1]]:11: warning: result of integer division used in + intFunc(sin(1 + 2 / 3)); +// CHECK-MESSAGES: :[[@LINE-1]]:19: warning: result of integer division used in + + floatArg(1 + intFunc(1 + 2 / 3)); + floatArg(1 + 3 * intFunc(a / b)); + + 1 << (2 / 3); + 1 << intFunc(2 / 3); + +#define M_SIN sin(a / b); + M_SIN +// CHECK-MESSAGES: :[[@LINE-1]]:3: warning: result of integer division used in + + intDivSin(a / b); +// CHECK-MESSAGES: :[[@LINE-1]]:20: warning: result of integer division used in + intDivSin(c / d); +// CHECK-MESSAGES: :[[@LINE-1]]:21: warning: result of integer division used in + intDivSin(f / g); +// CHECK-MESSAGES: :[[@LINE-1]]:26: warning: result of integer division used in + + floatArg(1 / 3); +// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: result of integer division used in + doubleArg(a / b); +// CHECK-MESSAGES: :[[@LINE-1]]:13: warning: result of integer division used in + longDoubleArg(3 / d); +// CHECK-MESSAGES: :[[@LINE-1]]:17: warning: result of integer division used in + floatArg(a / b / 0.1); +// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: result of integer division used in + doubleArg(1 / 3 / 0.1); +// CHECK-MESSAGES: :[[@LINE-1]]:13: warning: result of integer division used in + longDoubleArg(2 / 3 / 5); +// CHECK-MESSAGES: :[[@LINE-1]]:17: warning: result of integer division used in + + std::sin(2 / 3); +// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: result of integer division used in + ::acos(7 / d); +// CHECK-MESSAGES: :[[@LINE-1]]:10: warning: result of integer division used in + tanh(f / g); +// CHECK-MESSAGES: :[[@LINE-1]]:8: warning: result of integer division used in + + floatArg(0.1 / a / b); + doubleArg(0.1 / 3 / 1); + + singleDiv(); + wrongOrder(a,b); + rightOrder(a,b); + + sin(a / b); +// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: result of integer division used in + acos(f / d); +// CHECK-MESSAGES: :[[@LINE-1]]:8: warning: result of integer division used in + tanh(c / g); +// CHECK-MESSAGES: :[[@LINE-1]]:8: warning: result of integer division used in + + sin(3.0 / a); + acos(b / 3.14); + tanh(3.14 / f / g); +}