Mordante created this revision.
Mordante added reviewers: dblaikie, rsmith.
Mordante added a project: clang.
Converting a pointer to an integer whose result cannot represented in the
integer type is undefined behavior is C and prohibited in C++. C++ already has
a diagnostic when casting. This adds a diagnostic for C.
The diagnostic is not enabled by default due to the number of diagnostics it
triggered while running the tests.
Since this diagnostic uses the range of the conversion it also modifies
int-to-pointer-cast diagnostic to use a range.
Fixes PR8718: No warning on casting between pointer and non-pointer-sized int
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D72231
Files:
clang/docs/ReleaseNotes.rst
clang/include/clang/Basic/DiagnosticGroups.td
clang/include/clang/Basic/DiagnosticSemaKinds.td
clang/lib/Sema/SemaCast.cpp
clang/test/Sema/cast.c
Index: clang/test/Sema/cast.c
===================================================================
--- clang/test/Sema/cast.c
+++ clang/test/Sema/cast.c
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -fsyntax-only -triple x86_64-unknown-unknown %s -verify
+// RUN: %clang_cc1 -fsyntax-only -triple x86_64-unknown-unknown -Wpointer-to-int-cast %s -verify
typedef struct { unsigned long bits[(((1) + (64) - 1) / (64))]; } cpumask_t;
cpumask_t x;
@@ -151,19 +151,31 @@
}
void testVoidPtr(VoidPtr v) {
- (void) (Bool) v;
- (void) (Int) v;
+ (void) (Bool) v; // expected-warning{{cast to smaller integer type 'Bool' (aka '_Bool') from 'VoidPtr' (aka 'void *')}}
+ (void) (Int) v; // expected-warning{{cast to smaller integer type 'Int' (aka 'int') from 'VoidPtr' (aka 'void *')}}
(void) (Long) v;
(void) (VoidPtr) v;
(void) (CharPtr) v;
+ // Test that casts to void* can be controlled separately
+ // from other -Wpointer-to-int-cast warnings.
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wvoid-pointer-to-int-cast"
+ (void) (Bool) v; // no-warning
+#pragma clang diagnostic pop
}
void testCharPtr(CharPtr v) {
- (void) (Bool) v;
- (void) (Int) v;
+ (void) (Bool) v; // expected-warning{{cast to smaller integer type 'Bool' (aka '_Bool') from 'CharPtr' (aka 'char *')}}
+ (void) (Int) v; // expected-warning{{cast to smaller integer type 'Int' (aka 'int') from 'CharPtr' (aka 'char *')}}
(void) (Long) v;
(void) (VoidPtr) v;
(void) (CharPtr) v;
+ // Test that casts to void* can be controlled separately
+ // from other -Wpointer-to-int-cast warnings.
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wvoid-pointer-to-int-cast"
+ (void) (Bool) v; // expected-warning{{cast to smaller integer type 'Bool' (aka '_Bool') from 'CharPtr' (aka 'char *')}}
+#pragma clang diagnostic pop
}
typedef enum { x_a, x_b } X;
Index: clang/lib/Sema/SemaCast.cpp
===================================================================
--- clang/lib/Sema/SemaCast.cpp
+++ clang/lib/Sema/SemaCast.cpp
@@ -1961,7 +1961,7 @@
<< FD << DstCCName << FixItHint::CreateInsertion(NameLoc, CCAttrText);
}
-static void checkIntToPointerCast(bool CStyle, SourceLocation Loc,
+static void checkIntToPointerCast(bool CStyle, const SourceRange &OpRange,
const Expr *SrcExpr, QualType DestType,
Sema &Self) {
QualType SrcType = SrcExpr->getType();
@@ -1983,7 +1983,7 @@
unsigned Diag = DestType->isVoidPointerType() ?
diag::warn_int_to_void_pointer_cast
: diag::warn_int_to_pointer_cast;
- Self.Diag(Loc, Diag) << SrcType << DestType;
+ Self.Diag(OpRange.getBegin(), Diag) << SrcType << DestType << OpRange;
}
}
@@ -2218,8 +2218,7 @@
if (SrcType->isIntegralOrEnumerationType()) {
assert(destIsPtr && "One type must be a pointer");
- checkIntToPointerCast(CStyle, OpRange.getBegin(), SrcExpr.get(), DestType,
- Self);
+ checkIntToPointerCast(CStyle, OpRange, SrcExpr.get(), DestType, Self);
// C++ 5.2.10p5: A value of integral or enumeration type can be explicitly
// converted to a pointer.
// C++ 5.2.10p9: [Note: ...a null pointer constant of integral type is not
@@ -2734,8 +2733,8 @@
SrcExpr = ExprError();
return;
}
- checkIntToPointerCast(/* CStyle */ true, OpRange.getBegin(), SrcExpr.get(),
- DestType, Self);
+ checkIntToPointerCast(/* CStyle */ true, OpRange, SrcExpr.get(), DestType,
+ Self);
} else if (!SrcType->isArithmeticType()) {
if (!DestType->isIntegralType(Self.Context) &&
DestType->isArithmeticType()) {
@@ -2745,6 +2744,19 @@
SrcExpr = ExprError();
return;
}
+
+ if ((Self.Context.getTypeSize(SrcType) >
+ Self.Context.getTypeSize(DestType))) {
+ // C 6.3.2.3p6: Any pointer type may be converted to an integer type.
+ // Except as previously specified, the result is implementation-defined.
+ // If the result cannot be represented in the integer type, the behavior
+ // is undefined. The result need not be in the range of values of any
+ // integer type.
+ unsigned Diag = SrcType->isVoidPointerType()
+ ? diag::warn_void_pointer_to_int_cast
+ : diag::warn_pointer_to_int_cast;
+ Self.Diag(OpRange.getBegin(), Diag) << SrcType << DestType << OpRange;
+ }
}
if (Self.getLangOpts().OpenCL &&
Index: clang/include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3534,6 +3534,12 @@
def warn_int_to_void_pointer_cast : Warning<
"cast to %1 from smaller integer type %0">,
InGroup<IntToVoidPointerCast>;
+def warn_pointer_to_int_cast : Warning<
+ "cast to smaller integer type %1 from %0">,
+ InGroup<PointerToIntCast>, DefaultIgnore;
+def warn_void_pointer_to_int_cast : Warning<
+ "cast to smaller integer type %1 from %0">,
+ InGroup<VoidPointerToIntCast>, DefaultIgnore;
def warn_attribute_ignored_for_field_of_type : Warning<
"%0 attribute ignored for field of type %1">,
Index: clang/include/clang/Basic/DiagnosticGroups.td
===================================================================
--- clang/include/clang/Basic/DiagnosticGroups.td
+++ clang/include/clang/Basic/DiagnosticGroups.td
@@ -832,6 +832,9 @@
def IntToVoidPointerCast : DiagGroup<"int-to-void-pointer-cast">;
def IntToPointerCast : DiagGroup<"int-to-pointer-cast",
[IntToVoidPointerCast]>;
+def VoidPointerToIntCast : DiagGroup<"void-pointer-to-int-cast">;
+def PointerToIntCast : DiagGroup<"pointer-to-int-cast",
+ [VoidPointerToIntCast]>;
def Move : DiagGroup<"move", [
PessimizingMove,
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -64,6 +64,8 @@
- -Wbitwise-conditional-parentheses will warn on operator precedence issues
when mixing bitwise-and (&) and bitwise-or (|) operator with the
conditional operator (?:).
+- -Wpointer-to-int-cast is a new warning group. This group warns about C-style
+ casts of pointers to a integer type too small to hold all possible values.
Non-comprehensive list of changes in this release
-------------------------------------------------
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