[BoundsSafety] Switch new bounds checks on by default and adjust test suite

This makes clang behave as if
`-fbounds-safety-bringup-missing-checks=batch_0` was passed by default.
This enables all the new bounds check in the `batch_0` group by default
(which is currently all of them).

Making this change broke a lot of tests. To handle this the following
strategy was taken:

* To avoid losing test coverage for when the legacy bounds checks are
  a new `clang/test/BoundsSafety-legacy-checks` directory has been
  created and all the tests that failed have been copied into this
  directory. This directory has a `lit.local.cfg.py` file that means
  the `%clang_cc1` substitution contains
  `-fno-bounds-safety-bringup-missing-checks=all`. Doing that means all
  tests under this directory build with the new bounds checks disabled
  implicitly which means the copies of the tests didn't need
  modification to pass. We can delete this directory when we drop
  support for the legacy bounds checks.
* All failing tests under `clang/test/BoundsSafety` have been modified
  to pass with the new bounds checks enabled. Note I've not removed
  use of `-fbounds-safety-bringup-missing-checks=` under this test
  directory. This is something we should do as a separate clean up step.

This strategy means we haven't lost any test coverage and we have gained
much more test coverage for the new bounds checks.

Unfortunately while doing this I discovered that enabling the new bounds
checks breaks the experimental C++ support (see
`BoundsSafety/AST/value-dependence.cpp` and
`BoundsSafety/Sema/value-dependence.cpp`) (rdar://150044760). Given that
this feature isn't currently adopted this seems acceptable and is
something we can fix later if we need to.

Unfortunately I also discovered that `clang/test/BoundsSafety/CodeGen/unique-trap-blocks-O2.c`
is broken. I've XFAIL-ed the test and we'll need to fix a separate patch (rdar://150559639).

rdar://148623233

Author: delcypher

clang/lib/Basic/LangOptions.cpp

@@ -259,6 +259,6 @@ LangOptionsBase::getBoundsSafetyNewChecksMaskForGroup(StringRef GroupName) {
 
 LangOptionsBase::BoundsSafetyNewChecksMaskIntTy
 LangOptionsBase::getDefaultBoundsSafetyNewChecksMask() {
-  return BS_CHK_None;
+  return getBoundsSafetyNewChecksMaskForGroup("batch_0");
 }
 /* TO_UPSTREAM(BoundsSafety) OFF*/

clang/test/BoundsSafety-legacy-checks/AST/SystemHeaders/builtin-function-main.c

@@ -0,0 +1 @@
+../../../../BoundsSafety/AST/SystemHeaders/include/builtin-function-sys.h

clang/test/BoundsSafety-legacy-checks/AST/SystemHeaders/include/builtin-function-sys.h

@@ -5,7 +5,7 @@
 
 #include <ptrcheck.h>
 
-// TODO: Remove this test when return-size checks are enabled by default.
+// TODO: Remove this test when support for disabling return-size checks is removed.
 
 // CHECK: FunctionDecl [[func_cb_in_from_bidi:0x[^ ]+]] {{.+}} cb_in_from_bidi
 // CHECK: |-ParmVarDecl [[var_count:0x[^ ]+]]

clang/test/BoundsSafety/AST/bounds-attributed-in-return-disabled.c renamed to clang/test/BoundsSafety-legacy-checks/AST/bounds-attributed-in-return-disabled.c

@@ -0,0 +1,116 @@
+// RUN: %clang_cc1 -triple x86_64-apple-mac -ast-dump -fbounds-safety %s | FileCheck %s
+// RUN: %clang_cc1 -triple x86_64-apple-mac -ast-dump -fbounds-safety -x objective-c -fbounds-attributes-objc-experimental %s | FileCheck %s
+#include <ptrcheck.h>
+
+int *__counted_by(len) frob(int len);
+
+int *__sized_by(len) byte_frob(int len);
+void *alloc_bytes(int byte_count) __attribute__((alloc_size(1)));
+// <rdar://problem/70626464>
+// void *alloc_items(int byte_count, int size) __attribute__((alloc_size(1, 2)));
+
+typedef int (__array_decay_discards_count_in_parameters int_array_t)[10];
+void count_attr_in_bracket(int buf[__counted_by(len)], int len);
+void count_ignored_from_array(int (__array_decay_discards_count_in_parameters buf)[10]);
+void count_ignored_and_attr(int_array_t __counted_by(count) buf, int count);
+
+struct s {
+  int *__counted_by(l) bp;
+  int *bp2 __counted_by(l+1);
+  unsigned char *bp3 __sized_by(l);
+  unsigned char *bp4 __sized_by(l+1);
+  int l;
+};
+
+void test(void) {
+  int n = 0;
+  int *__counted_by(n) buf1;
+  int n2 = 0;
+  int *buf2 __counted_by(n2);
+  int n3 = sizeof(int) * n;
+  unsigned char *__sized_by(n3) byte_buf1;
+  int n4 = sizeof(int) * n2;
+  unsigned char *byte_buf2 __sized_by(n4);
+}
+
+int *__counted_by(len) frob_body(int len) { return 0; }
+int *__sized_by(len) byte_frob_body(int len) { return 0; }
+// CHECK:TranslationUnitDecl {{.*}}
+// CHECK:|-FunctionDecl {{.*}} frob 'int *__single __counted_by(len)(int)'
+// CHECK-NEXT:| `-ParmVarDecl {{.*}} used len 'int'
+// CHECK-NEXT:|-FunctionDecl {{.*}} byte_frob 'int *__single __sized_by(len)(int)'
+// CHECK-NEXT:| `-ParmVarDecl {{.*}} used len 'int'
+// CHECK-NEXT:|-FunctionDecl {{.*}} alloc_bytes 'void *__single(int)'
+// CHECK-NEXT:| |-ParmVarDecl {{.*}} byte_count 'int'
+// CHECK-NEXT:| `-AllocSizeAttr {{.*}} 1
+// CHECK-NEXT:|-TypedefDecl {{.*}} referenced int_array_t '__array_decay_discards_count_in_parameters int[10]':'int[10]'
+// CHECK-NEXT:| `-MacroQualifiedType {{.*}} '__array_decay_discards_count_in_parameters int[10]' sugar
+// CHECK-NEXT:|   `-AttributedType {{.*}} 'int[10] __attribute__((decay_discards_count_in_parameters))' sugar
+// CHECK-NEXT:|     `-ParenType {{.*}} 'int[10]' sugar
+// CHECK-NEXT:|       `-ConstantArrayType {{.*}} 'int[10]' 10
+// CHECK-NEXT:|         `-BuiltinType {{.*}} 'int'
+// CHECK-NEXT:|-FunctionDecl {{.*}} count_attr_in_bracket 'void (int *__single __counted_by(len), int)'
+// CHECK-NEXT:| |-ParmVarDecl {{.*}} buf 'int *__single __counted_by(len)':'int *__single'
+// CHECK-NEXT:| `-ParmVarDecl {{.*}} used len 'int'
+// CHECK-NEXT:|   `-DependerDeclsAttr {{.*}} Implicit {{.*}} 0
+// CHECK-NEXT:|-FunctionDecl {{.*}} count_ignored_from_array 'void (int *__single)'
+// CHECK-NEXT:| `-ParmVarDecl {{.*}} buf 'int *__single'
+// CHECK-NEXT:|-FunctionDecl {{.*}} count_ignored_and_attr 'void (int *__single __counted_by(count), int)'
+// CHECK-NEXT:| |-ParmVarDecl {{.*}} buf 'int *__single __counted_by(count)':'int *__single'
+// CHECK-NEXT:| `-ParmVarDecl {{.*}} used count 'int'
+// CHECK-NEXT:|   `-DependerDeclsAttr {{.*}} Implicit {{.*}} 0
+// CHECK-NEXT:|-RecordDecl {{.*}} struct s definition
+// CHECK-NEXT:| |-FieldDecl {{.*}} bp 'int *__single __counted_by(l)':'int *__single'
+// CHECK-NEXT:| |-FieldDecl {{.*}} bp2 'int *__single __counted_by(l + 1)':'int *__single'
+// CHECK-NEXT:| |-FieldDecl {{.*}} bp3 'unsigned char *__single __sized_by(l)':'unsigned char *__single'
+// CHECK-NEXT:| |-FieldDecl {{.*}} bp4 'unsigned char *__single __sized_by(l + 1)':'unsigned char *__single'
+// CHECK-NEXT:| `-FieldDecl {{.*}} referenced l 'int'
+// CHECK-NEXT:|   `-DependerDeclsAttr {{.*}} Implicit {{.*}} {{.*}} {{.*}} {{.*}} 0 0 0 0
+// CHECK-NEXT:|-FunctionDecl {{.*}} test 'void (void)'
+// CHECK-NEXT:| `-CompoundStmt {{.*}}
+// CHECK-NEXT:|   |-DeclStmt {{.*}}
+// CHECK-NEXT:|   | `-VarDecl {{.*}} used n 'int' cinit
+// CHECK-NEXT:|   |   |-IntegerLiteral {{.*}} 'int' 0
+// CHECK-NEXT:|   |   `-DependerDeclsAttr {{.*}} Implicit {{.*}} 0
+// CHECK-NEXT:|   |-DeclStmt {{.*}}
+// CHECK-NEXT:|   | `-VarDecl {{.*}} buf1 'int *__single __counted_by(n)':'int *__single'
+// CHECK-NEXT:|   |-DeclStmt {{.*}}
+// CHECK-NEXT:|   | `-VarDecl {{.*}} used n2 'int' cinit
+// CHECK-NEXT:|   |   |-IntegerLiteral {{.*}} 'int' 0
+// CHECK-NEXT:|   |   `-DependerDeclsAttr {{.*}} Implicit {{.*}} 0
+// CHECK-NEXT:|   |-DeclStmt {{.*}}
+// CHECK-NEXT:|   | `-VarDecl {{.*}} buf2 'int *__single __counted_by(n2)':'int *__single'
+// CHECK-NEXT:|   |-DeclStmt {{.*}}
+// CHECK-NEXT:|   | `-VarDecl {{.*}} used n3 'int' cinit
+// CHECK-NEXT:|   |   |-ImplicitCastExpr {{.*}} 'int' <IntegralCast>
+// CHECK-NEXT:|   |   | `-BinaryOperator {{.*}} 'unsigned long' '*'
+// CHECK-NEXT:|   |   |   |-UnaryExprOrTypeTraitExpr {{.*}} 'unsigned long' sizeof 'int'
+// CHECK-NEXT:|   |   |   `-ImplicitCastExpr {{.*}} 'unsigned long' <IntegralCast>
+// CHECK-NEXT:|   |   |     `-ImplicitCastExpr {{.*}} 'int' <LValueToRValue>
+// CHECK-NEXT:|   |   |       `-DeclRefExpr {{.*}} 'int' lvalue Var {{.*}} 'n' 'int'
+// CHECK-NEXT:|   |   `-DependerDeclsAttr {{.*}} Implicit {{.*}} 0
+// CHECK-NEXT:|   |-DeclStmt {{.*}}
+// CHECK-NEXT:|   | `-VarDecl {{.*}} byte_buf1 'unsigned char *__single __sized_by(n3)':'unsigned char *__single'
+// CHECK-NEXT:|   |-DeclStmt {{.*}}
+// CHECK-NEXT:|   | `-VarDecl {{.*}} used n4 'int' cinit
+// CHECK-NEXT:|   |   |-ImplicitCastExpr {{.*}} 'int' <IntegralCast>
+// CHECK-NEXT:|   |   | `-BinaryOperator {{.*}} 'unsigned long' '*'
+// CHECK-NEXT:|   |   |   |-UnaryExprOrTypeTraitExpr {{.*}} 'unsigned long' sizeof 'int'
+// CHECK-NEXT:|   |   |   `-ImplicitCastExpr {{.*}} 'unsigned long' <IntegralCast>
+// CHECK-NEXT:|   |   |     `-ImplicitCastExpr {{.*}} 'int' <LValueToRValue>
+// CHECK-NEXT:|   |   |       `-DeclRefExpr {{.*}} 'int' lvalue Var {{.*}} 'n2' 'int'
+// CHECK-NEXT:|   |   `-DependerDeclsAttr {{.*}} Implicit {{.*}} 0
+// CHECK-NEXT:|   `-DeclStmt {{.*}}
+// CHECK-NEXT:|     `-VarDecl {{.*}} byte_buf2 'unsigned char *__single __sized_by(n4)':'unsigned char *__single'
+// CHECK-NEXT:|-FunctionDecl {{.*}} frob_body 'int *__single __counted_by(len)(int)'
+// CHECK-NEXT:| |-ParmVarDecl {{.*}} used len 'int'
+// CHECK-NEXT:| `-CompoundStmt {{.*}}
+// CHECK-NEXT:|   `-ReturnStmt {{.*}}
+// CHECK-NEXT:|     `-ImplicitCastExpr {{.*}} 'int *__single __counted_by(len)':'int *__single' <NullToPointer>
+// CHECK-NEXT:|       `-IntegerLiteral {{.*}} 'int' 0
+// CHECK-NEXT:`-FunctionDecl {{.*}} byte_frob_body 'int *__single __sized_by(len)(int)'
+// CHECK-NEXT:  |-ParmVarDecl {{.*}} used len 'int'
+// CHECK-NEXT:  `-CompoundStmt {{.*}}
+// CHECK-NEXT:    `-ReturnStmt {{.*}}
+// CHECK-NEXT:      `-ImplicitCastExpr {{.*}} 'int *__single __sized_by(len)':'int *__single' <NullToPointer>
+// CHECK-NEXT:        `-IntegerLiteral {{.*}} 'int' 0