gchatelet updated this revision to Diff 172778.
gchatelet marked 7 inline comments as done.
gchatelet added a comment.
- Addressing comments and enhancing diagnostics
Repository:
rCTE Clang Tools Extra
https://reviews.llvm.org/D53488
Files:
clang-tidy/cppcoreguidelines/NarrowingConversionsCheck.cpp
clang-tidy/cppcoreguidelines/NarrowingConversionsCheck.h
docs/ReleaseNotes.rst
docs/clang-tidy/checks/cppcoreguidelines-narrowing-conversions.rst
test/clang-tidy/cppcoreguidelines-narrowing-conversions.cpp
Index: test/clang-tidy/cppcoreguidelines-narrowing-conversions.cpp
===================================================================
--- test/clang-tidy/cppcoreguidelines-narrowing-conversions.cpp
+++ test/clang-tidy/cppcoreguidelines-narrowing-conversions.cpp
@@ -1,4 +1,5 @@
-// RUN: %check_clang_tidy %s cppcoreguidelines-narrowing-conversions %t
+// RUN: %check_clang_tidy %s cppcoreguidelines-narrowing-conversions %t -- --
+// -target x86_64-unknown-linux
float ceil(float);
namespace std {
@@ -9,12 +10,12 @@
namespace floats {
struct ConvertsToFloat {
- operator float() const { return 0.5; }
+ operator float() const { return 0.5f; }
};
-float operator "" _Pa(unsigned long long);
+float operator"" _float(unsigned long long);
-void not_ok(double d) {
+void narrow_double_to_int_not_ok(double d) {
int i = 0;
i = d;
// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: narrowing conversion from 'double' to 'int' [cppcoreguidelines-narrowing-conversions]
@@ -24,11 +25,11 @@
// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: narrowing conversion from 'float' to 'int' [cppcoreguidelines-narrowing-conversions]
i = ConvertsToFloat();
// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: narrowing conversion from 'float' to 'int' [cppcoreguidelines-narrowing-conversions]
- i = 15_Pa;
+ i = 15_float;
// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: narrowing conversion from 'float' to 'int' [cppcoreguidelines-narrowing-conversions]
}
-void not_ok_binary_ops(double d) {
+void narrow_double_to_int_not_ok_binary_ops(double d) {
int i = 0;
i += 0.5;
// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: narrowing conversion from 'double' to 'int' [cppcoreguidelines-narrowing-conversions]
@@ -38,7 +39,7 @@
// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: narrowing conversion from 'double' to 'int' [cppcoreguidelines-narrowing-conversions]
// We warn on the following even though it's not dangerous because there is no
// reason to use a double literal here.
- // TODO(courbet): Provide an automatic fix.
+ // TODO: Provide an automatic fix if the number is exactly representable in the destination type.
i += 2.0;
// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: narrowing conversion from 'double' to 'int' [cppcoreguidelines-narrowing-conversions]
i += 2.0f;
@@ -52,6 +53,234 @@
// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: narrowing conversion from 'double' to 'int' [cppcoreguidelines-narrowing-conversions]
}
+double operator"" _double(unsigned long long);
+
+float narrow_double_to_float_return() {
+ return 0.5;
+ // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: narrowing conversion from 'double' to 'float' [cppcoreguidelines-narrowing-conversions]
+}
+
+void narrow_double_to_float_not_ok(double d) {
+ float f;
+ f = d;
+ // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: narrowing conversion from 'double' to 'float' [cppcoreguidelines-narrowing-conversions]
+ f = 0.5;
+ // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: narrowing conversion from 'double' to 'float' [cppcoreguidelines-narrowing-conversions]
+ f = 15_double;
+ // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: narrowing conversion from 'double' to 'float' [cppcoreguidelines-narrowing-conversions]
+}
+
+void narrow_double_to_float_not_ok_binary_ops(double d) {
+ float f;
+ f += 0.5;
+ // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: narrowing conversion from 'double' to 'float' [cppcoreguidelines-narrowing-conversions]
+ f += d;
+ // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: narrowing conversion from 'double' to 'float' [cppcoreguidelines-narrowing-conversions]
+ // We warn on the following even though it's not dangerous because there is no reason to use a double literal here.
+ // TODO: Provide an automatic fix if the number is exactly representable in the destination type.
+ f += 2.0;
+ // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: narrowing conversion from 'double' to 'float' [cppcoreguidelines-narrowing-conversions]
+
+ f *= 0.5;
+ // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: narrowing conversion from 'double' to 'float' [cppcoreguidelines-narrowing-conversions]
+ f /= 0.5;
+ // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: narrowing conversion from 'double' to 'float' [cppcoreguidelines-narrowing-conversions]
+ f += (double)0.5f;
+ // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: narrowing conversion from 'double' to 'float' [cppcoreguidelines-narrowing-conversions]
+}
+
+void narrow_integer_to_floating() {
+ {
+ long long ll; // 64 bits
+ float f = ll; // doesn't fit in 24 bits
+ // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: narrowing conversion from 'long long' to 'float' [cppcoreguidelines-narrowing-conversions]
+ double d = ll; // doesn't fit in 53 bits.
+ // CHECK-MESSAGES: :[[@LINE-1]]:16: warning: narrowing conversion from 'long long' to 'double' [cppcoreguidelines-narrowing-conversions]
+ }
+ {
+ int i; // 32 bits
+ float f = i; // doesn't fit in 24 bits
+ // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: narrowing conversion from 'int' to 'float' [cppcoreguidelines-narrowing-conversions]
+ double d = i; // fits in 53 bits.
+ }
+ {
+ short n1, n2;
+ float f = n1 + n2; // 'n1 + n2' is of type 'int' because of integer rules
+ // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: narrowing conversion from 'int' to 'float' [cppcoreguidelines-narrowing-conversions]
+ }
+ {
+ short s; // 16 bits
+ float f = s; // fits in 24 bits
+ double d = s; // fits in 53 bits.
+ }
+}
+
+void narrow_integer_to_unsigned_integer_is_ok() {
+ char c;
+ short s;
+ int i;
+ long l;
+ long long ll;
+
+ unsigned char uc;
+ unsigned short us;
+ unsigned int ui;
+ unsigned long ul;
+ unsigned long long ull;
+
+ ui = c;
+ uc = s;
+ uc = i;
+ uc = l;
+ uc = ll;
+
+ uc = uc;
+ uc = us;
+ uc = ui;
+ uc = ul;
+ uc = ull;
+}
+
+void narrow_integer_to_signed_integer_is_not_ok() {
+ char c;
+ short s;
+ int i;
+ long l;
+ long long ll;
+
+ unsigned char uc;
+ unsigned short us;
+ unsigned int ui;
+ unsigned long ul;
+ unsigned long long ull;
+
+ c = c;
+ c = s;
+ // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: narrowing conversion from 'short' to 'char' is implementation-defined [cppcoreguidelines-narrowing-conversions]
+ c = i;
+ // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: narrowing conversion from 'int' to 'char' is implementation-defined [cppcoreguidelines-narrowing-conversions]
+ c = l;
+ // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: narrowing conversion from 'long' to 'char' is implementation-defined [cppcoreguidelines-narrowing-conversions]
+ c = ll;
+ // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: narrowing conversion from 'long long' to 'char' is implementation-defined [cppcoreguidelines-narrowing-conversions]
+
+ c = uc;
+ // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: narrowing conversion from 'unsigned char' to 'char' is implementation-defined [cppcoreguidelines-narrowing-conversions]
+ c = us;
+ // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: narrowing conversion from 'unsigned short' to 'char' is implementation-defined [cppcoreguidelines-narrowing-conversions]
+ c = ui;
+ // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: narrowing conversion from 'unsigned int' to 'char' is implementation-defined [cppcoreguidelines-narrowing-conversions]
+ c = ul;
+ // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: narrowing conversion from 'unsigned long' to 'char' is implementation-defined [cppcoreguidelines-narrowing-conversions]
+ c = ull;
+ // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: narrowing conversion from 'unsigned long long' to 'char' is implementation-defined [cppcoreguidelines-narrowing-conversions]
+
+ i = c;
+ i = s;
+ i = i;
+ i = l;
+ // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: narrowing conversion from 'long' to 'int' is implementation-defined [cppcoreguidelines-narrowing-conversions]
+ i = ll;
+ // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: narrowing conversion from 'long long' to 'int' is implementation-defined [cppcoreguidelines-narrowing-conversions]
+
+ i = uc;
+ i = us;
+ i = ui;
+ // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: narrowing conversion from 'unsigned int' to 'int' is implementation-defined [cppcoreguidelines-narrowing-conversions]
+ i = ul;
+ // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: narrowing conversion from 'unsigned long' to 'int' is implementation-defined [cppcoreguidelines-narrowing-conversions]
+ i = ull;
+ // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: narrowing conversion from 'unsigned long long' to 'int' is implementation-defined [cppcoreguidelines-narrowing-conversions]
+
+ ll = c;
+ ll = s;
+ ll = i;
+ ll = l;
+ ll = ll;
+
+ ll = uc;
+ ll = us;
+ ll = ui;
+ ll = ul;
+ // CHECK-MESSAGES: :[[@LINE-1]]:8: warning: narrowing conversion from 'unsigned long' to 'long long' is implementation-defined [cppcoreguidelines-narrowing-conversions]
+ ll = ull;
+ // CHECK-MESSAGES: :[[@LINE-1]]:8: warning: narrowing conversion from 'unsigned long long' to 'long long' is implementation-defined [cppcoreguidelines-narrowing-conversions]
+}
+
+void narrow_constant_to_unsigned_integer_is_ok() {
+ unsigned char uc1 = 0;
+ unsigned char uc2 = 255;
+ unsigned char uc3 = -1; // unsigned dst type is well defined.
+ unsigned char uc4 = 256; // unsigned dst type is well defined.
+ unsigned short us1 = 0;
+ unsigned short us2 = 65535;
+ unsigned short us3 = -1; // unsigned dst type is well defined.
+ unsigned short us4 = 65536; // unsigned dst type is well defined.
+}
+
+void narrow_constant_to_signed_integer_is_not_ok() {
+ char c1 = -128;
+ char c2 = 127;
+ char c3 = -129;
+ // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: narrowing conversion from constant value -129 (0x00000000FFFFFF7F) of type 'int' to 'char' is implementation-defined [cppcoreguidelines-narrowing-conversions]
+ char c4 = 128;
+ // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: narrowing conversion from constant value 128 (0x0000000000000080) of type 'int' to 'char' is implementation-defined [cppcoreguidelines-narrowing-conversions]
+
+ short s1 = -32768;
+ short s2 = 32767;
+ short s3 = -32769;
+ // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: narrowing conversion from constant value -32769 (0x00000000FFFF7FFF) of type 'int' to 'short' is implementation-defined [cppcoreguidelines-narrowing-conversions]
+ short s4 = 32768;
+ // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: narrowing conversion from constant value 32768 (0x0000000000008000) of type 'int' to 'short' is implementation-defined [cppcoreguidelines-narrowing-conversions]
+}
+
+void narrow_conditional_operator_contant_to_unsigned_is_ok(bool b) {
+ // conversion to unsigned dst type is well defined.
+ unsigned char c1 = b ? 1 : 0;
+ unsigned char c2 = b ? 1 : 256;
+ unsigned char c3 = b ? -1 : 0;
+}
+
+void narrow_conditional_operator_contant_to_signed_is_not_ok(bool b) {
+ char uc1 = b ? 1 : 0;
+ char uc2 = b ? 1 : 128;
+ // CHECK-MESSAGES: :[[@LINE-1]]:22: warning: narrowing conversion from constant value 128 (0x0000000000000080) of type 'int' to 'char' is implementation-defined [cppcoreguidelines-narrowing-conversions]
+ char uc3 = b ? -129 : 0;
+ // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: narrowing conversion from constant value -129 (0x00000000FFFFFF7F) of type 'int' to 'char' is implementation-defined [cppcoreguidelines-narrowing-conversions]
+}
+
+void narrow_constant_to_floating_point() {
+ float f_ok = 1ULL << 24; // fits in 24 bits mantissa.
+ float f_not_ok = (1ULL << 24) + 1ULL; // doesn't fit in 24 bits mantissa.
+ // CHECK-MESSAGES: :[[@LINE-1]]:20: warning: narrowing conversion from constant value 16777217 of type 'unsigned long long' to 'float' [cppcoreguidelines-narrowing-conversions]
+ double d_ok = 1ULL << 53; // fits in 53 bits mantissa.
+ double d_not_ok = (1ULL << 53) + 1ULL; // doesn't fit in 53 bits mantissa.
+ // CHECK-MESSAGES: :[[@LINE-1]]:21: warning: narrowing conversion from constant value 9007199254740993 of type 'unsigned long long' to 'double' [cppcoreguidelines-narrowing-conversions]
+}
+
+void casting_integer_to_bool_is_ok() {
+ int i;
+ while (i) {
+ }
+ for (; i;) {
+ }
+ if (i) {
+ }
+}
+
+void casting_float_to_bool_is_not_ok() {
+ float f;
+ while (f) {
+ // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: narrowing conversion from 'float' to 'bool' [cppcoreguidelines-narrowing-conversions]
+ }
+ for (; f;) {
+ // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: narrowing conversion from 'float' to 'bool' [cppcoreguidelines-narrowing-conversions]
+ }
+ if (f) {
+ // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: narrowing conversion from 'float' to 'bool' [cppcoreguidelines-narrowing-conversions]
+ }
+}
+
void ok(double d) {
int i = 0;
i = 1;
@@ -89,15 +318,19 @@
void template_context() {
f(1, 2);
+ f(1, .5f);
f(1, .5);
+ f(1, .5l);
}
#define DERP(i, j) (i += j)
void macro_context() {
int i = 0;
DERP(i, 2);
+ DERP(i, .5f);
DERP(i, .5);
+ DERP(i, .5l);
}
-} // namespace floats
+} // namespace floats
Index: docs/clang-tidy/checks/cppcoreguidelines-narrowing-conversions.rst
===================================================================
--- docs/clang-tidy/checks/cppcoreguidelines-narrowing-conversions.rst
+++ docs/clang-tidy/checks/cppcoreguidelines-narrowing-conversions.rst
@@ -10,13 +10,17 @@
This rule is part of the "Expressions and statements" profile of the C++ Core
Guidelines, corresponding to rule ES.46. See
-https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#Res-narrowing.
+https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#es46-avoid-lossy-narrowing-truncating-arithmetic-conversions.
-We enforce only part of the guideline, more specifically, we flag:
- - All floating-point to integer conversions that are not marked by an explicit
- cast (c-style or ``static_cast``). For example: ``int i = 0; i += 0.1;``,
- ``void f(int); f(0.1);``,
- - All applications of binary operators where the left-hand-side is an integer
- and the right-hand-size is a floating-point. For example:
- ``int i; i+= 0.1;``.
+We enforce only part of the guideline, more specifically, we flag narrowing conversions from:
+ - an integer to a narrower integer (e.g. ``char`` to ``unsigned char``),
+ - an integer to a narrower floating-point (e.g. ``uint64_t`` to ``float``),
+ - a floating-point to an integer (e.g. ``double`` to ``int``),
+ - a floating-point to a narrower floating-point (e.g. ``double`` to ``float``).
+This check will flag:
+ - All narrowing conversions that are not marked by an explicit cast (c-style or
+ ``static_cast``). For example: ``int i = 0; i += 0.1;``,
+ ``void f(int); f(0.1);``,
+ - All applications of binary operators with a narrowing conversions.
+ For example: ``int i; i+= 0.1;``.
Index: docs/ReleaseNotes.rst
===================================================================
--- docs/ReleaseNotes.rst
+++ docs/ReleaseNotes.rst
@@ -182,6 +182,11 @@
<clang-tidy/checks/readability-redundant-smartptr-get>` check does not warn
about calls inside macros anymore by default.
+- The :doc:`cppcoreguidelines-narrowing-conversions
+ <clang-tidy/checks/cppcoreguidelines-narrowing-conversions>` check now
+ detects narrowing conversions between floating-point types
+ (e.g. ``double`` to ``float``).
+
Improvements to include-fixer
-----------------------------
Index: clang-tidy/cppcoreguidelines/NarrowingConversionsCheck.h
===================================================================
--- clang-tidy/cppcoreguidelines/NarrowingConversionsCheck.h
+++ clang-tidy/cppcoreguidelines/NarrowingConversionsCheck.h
@@ -28,6 +28,27 @@
: ClangTidyCheck(Name, Context) {}
void registerMatchers(ast_matchers::MatchFinder *Finder) override;
void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+
+private:
+ void diagIfNarrowType(const ASTContext &Context, SourceLocation SourceLoc,
+ const Expr *Lhs, const Expr *Rhs);
+
+ void diagIfNarrowConstantIntegral(const ASTContext &Context,
+ SourceLocation SourceLoc, const Expr *Lhs,
+ const Expr *Rhs,
+ const llvm::APSInt &RhsIntegerConstant);
+
+ bool diagIfNarrowConstant(const ASTContext &Context, SourceLocation SourceLoc,
+ const Expr *Lhs, const Expr *Rhs);
+
+ bool diagIfNarrowConstantInConditionalOperator(const ASTContext &Context,
+ SourceLocation SourceLoc,
+ const Expr *Lhs,
+ const Expr *Rhs);
+
+ void diagIfNarrower(const ASTContext &Context, SourceLocation BeginLoc,
+ SourceLocation SourceLoc, const Expr *Lhs,
+ const Expr *Rhs);
};
} // namespace cppcoreguidelines
Index: clang-tidy/cppcoreguidelines/NarrowingConversionsCheck.cpp
===================================================================
--- clang-tidy/cppcoreguidelines/NarrowingConversionsCheck.cpp
+++ clang-tidy/cppcoreguidelines/NarrowingConversionsCheck.cpp
@@ -9,60 +9,300 @@
#include "NarrowingConversionsCheck.h"
#include "clang/AST/ASTContext.h"
+#include "clang/AST/Type.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "llvm/ADT/APSInt.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/Mutex.h"
+
+#include <cstdint>
using namespace clang::ast_matchers;
namespace clang {
namespace tidy {
namespace cppcoreguidelines {
-// FIXME: Check double -> float truncation. Pay attention to casts:
void NarrowingConversionsCheck::registerMatchers(MatchFinder *Finder) {
// ceil() and floor() are guaranteed to return integers, even though the type
// is not integral.
- const auto IsCeilFloorCall = callExpr(callee(functionDecl(
- hasAnyName("::ceil", "::std::ceil", "::floor", "::std::floor"))));
-
- const auto IsFloatExpr =
- expr(hasType(realFloatingPointType()), unless(IsCeilFloorCall));
+ const auto IsCeilFloorCallExpr = expr(callExpr(callee(functionDecl(
+ hasAnyName("::ceil", "::std::ceil", "::floor", "::std::floor")))));
- // casts:
+ // Casts:
// i = 0.5;
// void f(int); f(0.5);
- Finder->addMatcher(implicitCastExpr(hasImplicitDestinationType(isInteger()),
- hasSourceExpression(IsFloatExpr),
- unless(hasParent(castExpr())),
- unless(isInTemplateInstantiation()))
- .bind("cast"),
- this);
+ Finder->addMatcher(
+ implicitCastExpr(hasImplicitDestinationType(builtinType()),
+ hasSourceExpression(hasType(builtinType())),
+ unless(hasSourceExpression(IsCeilFloorCallExpr)),
+ unless(hasParent(castExpr())),
+ unless(isInTemplateInstantiation()))
+ .bind("cast"),
+ this);
// Binary operators:
// i += 0.5;
- Finder->addMatcher(
- binaryOperator(isAssignmentOperator(),
- // The `=` case generates an implicit cast which is covered
- // by the previous matcher.
- unless(hasOperatorName("=")),
- hasLHS(hasType(isInteger())), hasRHS(IsFloatExpr),
- unless(isInTemplateInstantiation()))
- .bind("op"),
- this);
+ Finder->addMatcher(binaryOperator(isAssignmentOperator(),
+ hasLHS(expr(hasType(builtinType()))),
+ hasRHS(expr(hasType(builtinType()))),
+ unless(hasRHS(IsCeilFloorCallExpr)),
+ unless(isInTemplateInstantiation()),
+ // The `=` case generates an implicit cast
+ // which is covered by the previous matcher.
+ unless(hasOperatorName("=")))
+ .bind("binary_op"),
+ this);
}
-void NarrowingConversionsCheck::check(const MatchFinder::MatchResult &Result) {
- if (const auto *Op = Result.Nodes.getNodeAs<BinaryOperator>("op")) {
- if (Op->getBeginLoc().isMacroID())
+static const BuiltinType *getBuiltinType(const Expr *E) {
+ if (const Type *T = E->getType().getCanonicalType().getTypePtrOrNull())
+ return T->getAs<BuiltinType>();
+ return nullptr;
+}
+
+namespace {
+
+struct IntegerRange {
+ bool Contains(const IntegerRange &From) const {
+ return (llvm::APSInt::compareValues(Lower, From.Lower) <= 0) &&
+ (llvm::APSInt::compareValues(Upper, From.Upper) >= 0);
+ }
+
+ bool Contains(const llvm::APSInt &Value) const {
+ return (llvm::APSInt::compareValues(Lower, Value) <= 0) &&
+ (llvm::APSInt::compareValues(Upper, Value) >= 0);
+ }
+
+ llvm::APSInt Lower;
+ llvm::APSInt Upper;
+};
+
+} // namespace
+
+static IntegerRange createFromType(const ASTContext &Context,
+ const BuiltinType *T) {
+ assert(T && "T must not be nullptr");
+ if (T->isFloatingPoint()) {
+ unsigned PrecisionBits = llvm::APFloatBase::semanticsPrecision(
+ Context.getFloatTypeSemantics(T->desugar()));
+ // Contrary to two's complement integer, floating point values are
+ // symmetric and have the same number of positive and negative values.
+ // The range of valid integer for a floating point value is:
+ // [-2^PrecisionBits, 2^PrecisionBits]
+
+ // Values are created with PrecisionBits plus two bytes:
+ // - One to express the missing negative value of 2's complement
+ // representation.
+ // - One for the sign.
+ llvm::APSInt UpperValue(PrecisionBits + 2, /*isUnsigned*/ false);
+ UpperValue.setBit(PrecisionBits);
+ llvm::APSInt LowerValue(PrecisionBits + 2, /*isUnsigned*/ false);
+ LowerValue.setBit(PrecisionBits);
+ LowerValue.setSignBit();
+ return {LowerValue, UpperValue};
+ }
+ if (T->isSignedInteger())
+ return {llvm::APSInt::getMinValue(Context.getTypeSize(T), false),
+ llvm::APSInt::getMaxValue(Context.getTypeSize(T), false)};
+ if (T->isUnsignedInteger())
+ return {llvm::APSInt::getMinValue(Context.getTypeSize(T), true),
+ llvm::APSInt::getMaxValue(Context.getTypeSize(T), true)};
+
+ llvm::errs() << "Unhandled type " << T->getName(Context.getPrintingPolicy())
+ << "\n";
+ llvm_unreachable("Unhandled type");
+}
+
+static bool isWideEnoughToHold(const ASTContext &Context,
+ const BuiltinType *FromType,
+ const BuiltinType *ToType) {
+ IntegerRange FromIntegerRange = createFromType(Context, FromType);
+ IntegerRange ToIntegerRange = createFromType(Context, ToType);
+ return ToIntegerRange.Contains(FromIntegerRange);
+}
+
+static bool isWideEnoughToHold(const ASTContext &Context,
+ const llvm::APSInt &IntegerConstant,
+ const BuiltinType *ToType) {
+ IntegerRange ToIntegerRange = createFromType(Context, ToType);
+ return ToIntegerRange.Contains(IntegerConstant);
+}
+
+static QualType getUnqualifiedType(const Expr *Expr) {
+ return Expr->getType().getUnqualifiedType();
+}
+
+static llvm::SmallString<64> getValueAsString(const llvm::APSInt &Value,
+ uint64_t HexBytes) {
+ llvm::SmallString<64> Str;
+ Value.toString(Str, 10);
+ if (HexBytes > 0) {
+ Str.append(" (0x");
+ llvm::SmallString<32> HexValue;
+ Value.toStringUnsigned(HexValue, 16);
+ for (size_t I = HexValue.size(); I < (HexBytes / 2); ++I)
+ Str.append("0");
+ Str.append(HexValue);
+ Str.append(")");
+ }
+ return Str;
+}
+
+void NarrowingConversionsCheck::diagIfNarrowType(const ASTContext &Context,
+ SourceLocation SourceLoc,
+ const Expr *Lhs,
+ const Expr *Rhs) {
+ const BuiltinType *ToType = getBuiltinType(Lhs);
+ const BuiltinType *FromType = getBuiltinType(Rhs);
+ if (ToType == FromType || ToType == nullptr || FromType == nullptr ||
+ ToType->isInstantiationDependentType() ||
+ FromType->isInstantiationDependentType())
+ return;
+
+ if (FromType->isRealFloatingType() && ToType->isIntegerType()) {
+ diag(SourceLoc, "narrowing conversion from %0 to %1")
+ << getUnqualifiedType(Rhs) << getUnqualifiedType(Lhs);
+ return;
+ }
+
+ if (FromType->isIntegerType() && ToType->isIntegerType()) {
+ // Integer to Bool type conversions are well defined and not considered as a
+ // narrowing. The following clang tidy already flags invalid boolean
+ // conversions.
+ // https://clang.llvm.org/extra/clang-tidy/checks/readability-implicit-bool-conversion.html
+ if ((ToType->getKind() == BuiltinType::Bool) ||
+ (FromType->getKind() == BuiltinType::Bool))
+ return;
+ // Conversions to unsigned integer are well defined and follow modulo 2
+ // arithmetic.
+ if (ToType->isUnsignedInteger())
return;
- diag(Op->getOperatorLoc(), "narrowing conversion from %0 to %1")
- << Op->getRHS()->getType() << Op->getLHS()->getType();
+ // Destination type is signed, narrowing would lead to implementation
+ // defined behavior.
+ if (!isWideEnoughToHold(Context, FromType, ToType))
+ diag(SourceLoc,
+ "narrowing conversion from %0 to %1 is implementation-defined")
+ << getUnqualifiedType(Rhs) << getUnqualifiedType(Lhs);
+ return;
+ }
+
+ // TODO: Guard by an Option since this is expected to trigger often.
+ if (FromType->isRealFloatingType() && ToType->isRealFloatingType()) {
+ if (ToType->getKind() < FromType->getKind())
+ diag(SourceLoc, "narrowing conversion from %0 to %1")
+ << getUnqualifiedType(Rhs) << getUnqualifiedType(Lhs);
+ return;
+ }
+
+ if (FromType->isIntegerType() && ToType->isRealFloatingType()) {
+ if (!isWideEnoughToHold(Context, FromType, ToType))
+ diag(SourceLoc, "narrowing conversion from %0 to %1")
+ << getUnqualifiedType(Rhs) << getUnqualifiedType(Lhs);
+ return;
+ }
+
+ llvm::errs() << "Unhandled from type "
+ << FromType->getName(Context.getPrintingPolicy()) << "or to type"
+ << ToType->getName(Context.getPrintingPolicy()) << "\n";
+ llvm_unreachable("Unhandled case");
+}
+
+void NarrowingConversionsCheck::diagIfNarrowConstantIntegral(
+ const ASTContext &Context, SourceLocation SourceLoc, const Expr *Lhs,
+ const Expr *Rhs, const llvm::APSInt &RhsIntegerConstant) {
+ const BuiltinType *ToType = getBuiltinType(Lhs);
+ const BuiltinType *FromType = getBuiltinType(Rhs);
+ assert(ToType && "Lhs must be a builtin type");
+ assert(FromType && "Rhs must be a builtin type");
+ assert(FromType->isInteger() && "Rhs is integer constant");
+ // The AST already handles promotion rules so we're only checking conversion
+ // rules (https://en.cppreference.com/w/cpp/language/implicit_conversion).
+
+ if (ToType->isBooleanType())
+ return; // conversion to bool value is well defined.
+
+ if (ToType->isUnsignedInteger())
+ return; // conversion to unsigned integer value is well defined.
+
+ // Narrowing from an integer to a signed integer is implementation-defined.
+ if (ToType->isSignedInteger() &&
+ !isWideEnoughToHold(Context, RhsIntegerConstant, ToType)) {
+ diag(SourceLoc, "narrowing conversion from constant value %0 of type %1 to "
+ "%2 is implementation-defined")
+ << getValueAsString(RhsIntegerConstant, Context.getTypeSize(FromType))
+ << getUnqualifiedType(Rhs) << getUnqualifiedType(Lhs);
return;
}
- const auto *Cast = Result.Nodes.getNodeAs<ImplicitCastExpr>("cast");
- if (Cast->getBeginLoc().isMacroID())
+
+ // Narrowing from an integer to a floating point type.
+ if (ToType->isFloatingPoint() &&
+ !isWideEnoughToHold(Context, RhsIntegerConstant, ToType)) {
+ diag(SourceLoc,
+ "narrowing conversion from constant value %0 of type %1 to %2")
+ << getValueAsString(RhsIntegerConstant, /*NoHex*/ 0)
+ << getUnqualifiedType(Rhs) << getUnqualifiedType(Lhs);
return;
- diag(Cast->getExprLoc(), "narrowing conversion from %0 to %1")
- << Cast->getSubExpr()->getType() << Cast->getType();
+ }
+}
+
+bool NarrowingConversionsCheck::diagIfNarrowConstant(const ASTContext &Context,
+ SourceLocation SourceLoc,
+ const Expr *Lhs,
+ const Expr *Rhs) {
+ if (Lhs->isInstantiationDependent() || Rhs->isInstantiationDependent())
+ return false;
+
+ llvm::APSInt IntegerConstant;
+ if (Rhs->isIntegerConstantExpr(IntegerConstant, Context)) {
+ diagIfNarrowConstantIntegral(Context, SourceLoc, Lhs, Rhs, IntegerConstant);
+ return true;
+ }
+
+ // TODO: Handle floating point constant conversions as well.
+
+ return false;
+}
+
+bool NarrowingConversionsCheck::diagIfNarrowConstantInConditionalOperator(
+ const ASTContext &Context, SourceLocation SourceLoc, const Expr *Lhs,
+ const Expr *Rhs) {
+ if (const auto *CO = llvm::dyn_cast<ConditionalOperator>(Rhs)) {
+ // We create variables so we make sure both sides of the
+ // ConditionalOperator are evaluated, the || operator would shortciruit
+ // the second call otherwise.
+ bool NarrowLhs = diagIfNarrowConstant(Context, CO->getLHS()->getExprLoc(),
+ Lhs, CO->getLHS());
+ bool NarrowRhs = diagIfNarrowConstant(Context, CO->getRHS()->getExprLoc(),
+ Lhs, CO->getRHS());
+ return NarrowLhs || NarrowRhs;
+ }
+ return false;
+}
+
+void NarrowingConversionsCheck::diagIfNarrower(const ASTContext &Context,
+ SourceLocation BeginLoc,
+ SourceLocation SourceLoc,
+ const Expr *Lhs,
+ const Expr *Rhs) {
+ if (BeginLoc.isMacroID())
+ return;
+ if (diagIfNarrowConstantInConditionalOperator(Context, SourceLoc, Lhs, Rhs))
+ return;
+ if (diagIfNarrowConstant(Context, SourceLoc, Lhs, Rhs))
+ return;
+ diagIfNarrowType(Context, SourceLoc, Lhs, Rhs);
+}
+
+void NarrowingConversionsCheck::check(const MatchFinder::MatchResult &Result) {
+ if (const auto *Op = Result.Nodes.getNodeAs<BinaryOperator>("binary_op"))
+ return diagIfNarrower(*Result.Context, Op->getBeginLoc(),
+ Op->getOperatorLoc(), Op->getLHS(), Op->getRHS());
+ if (const auto *Cast = Result.Nodes.getNodeAs<ImplicitCastExpr>("cast"))
+ return diagIfNarrower(*Result.Context, Cast->getBeginLoc(),
+ Cast->getExprLoc(), Cast, Cast->getSubExpr());
+ llvm_unreachable("must be binary operator or cast expression");
}
} // namespace cppcoreguidelines
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