[clang] [-Wunsafe-buffer-usage] Introduce std::array fixits (PR #80084)

[Ziqing Luo via cfe-commits]

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@@ -0,0 +1,164 @@
+// RUN: %clang_cc1 -std=c++20 -Wunsafe-buffer-usage \
+// RUN:            -fsafe-buffer-usage-suggestions \
+// RUN:            -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s
+typedef int * Int_ptr_t;
+typedef int Int_t;
+
+void simple(unsigned idx) {
+  int buffer[10];
+// CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:3-[[@LINE-1]]:17}:"std::array<int, 10> buffer"
+  buffer[idx] = 0;
+}
+
+void whitespace_in_declaration(unsigned idx) {
+  int      buffer_w   [       10 ];
+// CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:3-[[@LINE-1]]:35}:"std::array<int, 10> buffer_w"
+  buffer_w[idx] = 0;
+}
+
+void comments_in_declaration(unsigned idx) {
+  int   /* [A] */   buffer_w  /* [B] */ [  /* [C] */ 10 /* [D] */  ] ;
+// CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:3-[[@LINE-1]]:69}:"std::array<int   /* [A] */, /* [C] */ 10 /* [D] */> buffer_w"
+  buffer_w[idx] = 0;
+}
+
+void initializer(unsigned idx) {
+  int buffer[3] = {0};
+// CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:3-[[@LINE-1]]:16}:"std::array<int, 3> buffer"
+
+  int buffer2[3] = {0, 1, 2};
+// CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:3-[[@LINE-1]]:17}:"std::array<int, 3> buffer2"
+
+  buffer[idx] = 0;
+  buffer2[idx] = 0;
+}
+
+void auto_size(unsigned idx) {
+  int buffer[] = {0, 1, 2};
+// CHECK-NOT: fix-it:"{{.*}}":{[[@LINE-1]]
+// FIXME: implement support
+
+  buffer[idx] = 0;
+}
+
+void universal_initialization(unsigned idx) {
+  int buffer[] {0, 1, 2};
+// CHECK-NOT: fix-it:"{{.*}}":{[[@LINE-1]]
+// FIXME: implement support
+
+  buffer[idx] = 0;
+}
+
+void multi_decl1(unsigned idx) {
+  int a, buffer[10];
+// CHECK-NOT: fix-it:"{{.*}}":{[[@LINE-1]]
+// FIXME: implement support
+
+  buffer[idx] = 0;
+}
+
+void multi_decl2(unsigned idx) {
+  int buffer[10], b;
+// CHECK-NOT: fix-it:"{{.*}}":{[[@LINE-1]]
+// FIXME: implement support
+
+  buffer[idx] = 0;
+}
+
+void local_array_ptr_to_const(unsigned idx, const int*& a) {
+  const int * buffer[10] = {a};
+// CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:3-[[@LINE-1]]:25}:"std::array<const int *, 10> buffer"
+  a = buffer[idx];
+}
+
+void local_array_const_ptr(unsigned idx, int*& a) {
+  int * const buffer[10] = {a};
+// CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:3-[[@LINE-1]]:25}:"std::array<int * const, 10> buffer"
+
+  a = buffer[idx];
+}
+
+void local_array_const_ptr_via_typedef(unsigned idx, int*& a) {
+  typedef int * const my_const_ptr;
+  my_const_ptr buffer[10] = {a};
+// CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:3-[[@LINE-1]]:26}:"std::array<my_const_ptr, 10> buffer"
+
+  a = buffer[idx];
+}
+
+void local_array_const_ptr_to_const(unsigned idx, const int*& a) {
+  const int * const buffer[10] = {a};
+// CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:3-[[@LINE-1]]:31}:"std::array<const int * const, 10> buffer"
+
+  a = buffer[idx];
+
+}
+
+template<typename T>
+void unsupported_local_array_in_template(unsigned idx) {
+  T buffer[10];
+// CHECK-NOT: fix-it:"{{.*}}":{[[@LINE-1]]:.*-[[@LINE-1]]:.*}
+  buffer[idx] = 0;
+}
+// Instantiate the template function to force its analysis.
+template void unsupported_local_array_in_template<int>(unsigned);
+
+typedef unsigned int my_uint;
+void typedef_as_elem_type(unsigned idx) {
+  my_uint buffer[10];
+// CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:3-[[@LINE-1]]:21}:"std::array<my_uint, 10> buffer"
+  buffer[idx] = 0;
+}
+
+void macro_as_elem_type(unsigned idx) {
+#define MY_INT int
+  MY_INT buffer[10];
+// CHECK-NOT: fix-it:"{{.*}}":{[[@LINE-1]]:.*-[[@LINE-1]]:.*}
+// FIXME: implement support
+
+  buffer[idx] = 0;
+#undef MY_INT
+}
+
+void macro_as_identifier(unsigned idx) {
+#define MY_BUFFER buffer
+  int MY_BUFFER[10];
+// CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:3-[[@LINE-1]]:20}:"std::array<int, 10> MY_BUFFER"
+  MY_BUFFER[idx] = 0;
+#undef MY_BUFFER
+}
+
+void macro_as_size(unsigned idx) {
+#define MY_TEN 10
+  int buffer[MY_TEN];
+// CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:3-[[@LINE-1]]:21}:"std::array<int, MY_TEN> buffer"
+  buffer[idx] = 0;
+#undef MY_TEN
+}
+
+void constant_as_size(unsigned idx) {
+  const unsigned my_const = 10;
+  int buffer[my_const];
+// CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:3-[[@LINE-1]]:23}:"std::array<int, my_const> buffer"
+  buffer[idx] = 0;
+}
+
+void subscript_negative() {
+  int buffer[10];
+// CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:3-[[@LINE-1]]:17}:"std::array<int, 10> buffer"
+
+  // For constant-size arrays any negative index will lead to buffer underflow.
+  // std::array::operator[] has unsigned parameter so the value will be casted to unsigned.
+  // This will very likely be buffer overflow but hardened std::array catch these at runtime.
+  buffer[-5] = 0;
+}
+
+void subscript_signed(int signed_idx) {
+  int buffer[10];
+// CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:3-[[@LINE-1]]:17}:"std::array<int, 10> buffer"
+
+  // For constant-size arrays any negative index will lead to buffer underflow.
+  // std::array::operator[] has unsigned parameter so the value will be casted to unsigned.
+  // This will very likely be buffer overflow but hardened std::array catches these at runtime.
+  buffer[signed_idx] = 0;
+}
----------------
ziqingluo-90 wrote:

maybe we can have a test showing that multi-dimentional arrays will not be fixed?

https://github.com/llvm/llvm-project/pull/80084