jamieschmeiser created this revision.
jamieschmeiser added a reviewer: andrew.w.kaylor.
jamieschmeiser requested review of this revision.
Herald added a project: clang.
Test and produce warning for subtracting a pointer from null or subtracting
null from a pointer. Reuse existing warning that this is undefined behaviour.
Also add unit test for both warnings.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D98798
Files:
clang/lib/Sema/SemaExpr.cpp
clang/test/Sema/pointer-addition.c
Index: clang/test/Sema/pointer-addition.c
===================================================================
--- clang/test/Sema/pointer-addition.c
+++ clang/test/Sema/pointer-addition.c
@@ -29,4 +29,6 @@
// Cases that don't match the GNU inttoptr idiom get a different warning.
f = (char*)0 - i; // expected-warning {{performing pointer arithmetic on a
null pointer has undefined behavior}}
int *g = (int*)0 + i; // expected-warning {{performing pointer arithmetic on
a null pointer has undefined behavior}}
+ f = (char*)((char*)0 - f); // expected-warning {{performing pointer
arithmetic on a null pointer has undefined behavior}}
+ f = (char*)(f - (char*)0); // expected-warning {{performing pointer
arithmetic on a null pointer has undefined behavior}}
}
Index: clang/lib/Sema/SemaExpr.cpp
===================================================================
--- clang/lib/Sema/SemaExpr.cpp
+++ clang/lib/Sema/SemaExpr.cpp
@@ -10720,7 +10720,15 @@
LHS.get(), RHS.get()))
return QualType();
- // FIXME: Add warnings for nullptr - ptr.
+ // Subtracting from a null pointer should produce a warning.
+ if (LHS.get()->IgnoreParenCasts()->isNullPointerConstant(Context,
+ Expr::NPC_ValueDependentIsNotNull))
+ diagnoseArithmeticOnNullPointer(*this, Loc, LHS.get(), false);
+
+ // Subtracting a null pointer should produce a warning.
+ if (RHS.get()->IgnoreParenCasts()->isNullPointerConstant(Context,
+ Expr::NPC_ValueDependentIsNotNull))
+ diagnoseArithmeticOnNullPointer(*this, Loc, RHS.get(), false);
// The pointee type may have zero size. As an extension, a structure or
// union may have zero size or an array may have zero length. In this
Index: clang/test/Sema/pointer-addition.c
===================================================================
--- clang/test/Sema/pointer-addition.c
+++ clang/test/Sema/pointer-addition.c
@@ -29,4 +29,6 @@
// Cases that don't match the GNU inttoptr idiom get a different warning.
f = (char*)0 - i; // expected-warning {{performing pointer arithmetic on a null pointer has undefined behavior}}
int *g = (int*)0 + i; // expected-warning {{performing pointer arithmetic on a null pointer has undefined behavior}}
+ f = (char*)((char*)0 - f); // expected-warning {{performing pointer arithmetic on a null pointer has undefined behavior}}
+ f = (char*)(f - (char*)0); // expected-warning {{performing pointer arithmetic on a null pointer has undefined behavior}}
}
Index: clang/lib/Sema/SemaExpr.cpp
===================================================================
--- clang/lib/Sema/SemaExpr.cpp
+++ clang/lib/Sema/SemaExpr.cpp
@@ -10720,7 +10720,15 @@
LHS.get(), RHS.get()))
return QualType();
- // FIXME: Add warnings for nullptr - ptr.
+ // Subtracting from a null pointer should produce a warning.
+ if (LHS.get()->IgnoreParenCasts()->isNullPointerConstant(Context,
+ Expr::NPC_ValueDependentIsNotNull))
+ diagnoseArithmeticOnNullPointer(*this, Loc, LHS.get(), false);
+
+ // Subtracting a null pointer should produce a warning.
+ if (RHS.get()->IgnoreParenCasts()->isNullPointerConstant(Context,
+ Expr::NPC_ValueDependentIsNotNull))
+ diagnoseArithmeticOnNullPointer(*this, Loc, RHS.get(), false);
// The pointee type may have zero size. As an extension, a structure or
// union may have zero size or an array may have zero length. In this
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
