Index: clang/lib/Analysis/UnsafeBufferUsage.cpp
===================================================================
--- clang/lib/Analysis/UnsafeBufferUsage.cpp
+++ clang/lib/Analysis/UnsafeBufferUsage.cpp
@@ -164,23 +164,38 @@
   // A UPC can be
   // 1. an argument of a function call (except the callee has [[unsafe_...]]
   // attribute), or
-  // 2. the operand of a cast operation; or
+  // 2. the operand of a cast-to-(Integer or Boolean) operation; or
+  // 3. the operand of a pointer subtraction operation
+  //    (i.e., computing the distance between two pointers); or
+  // 4. the operand of a pointer comparison operation; or
   // ...
   auto CallArgMatcher =
-      callExpr(forEachArgumentWithParam(InnerMatcher, 
+      callExpr(forEachArgumentWithParam(InnerMatcher,
                   hasPointerType() /* array also decays to pointer type*/),
           unless(callee(functionDecl(hasAttr(attr::UnsafeBufferUsage)))));
 
   auto CastOperandMatcher =
-      explicitCastExpr(hasCastKind(CastKind::CK_PointerToIntegral),
-                       castSubExpr(allOf(hasPointerType(), InnerMatcher)));
+    castExpr(anyOf(hasCastKind(CastKind::CK_PointerToIntegral),
+		   hasCastKind(CastKind::CK_PointerToBoolean)),
+	     castSubExpr(allOf(hasPointerType(), InnerMatcher)));
+
+  // A matcher that matches pointer subtractions:
+  auto PtrSubtractionMatcher =
+    binaryOperator(hasOperatorName("-"),
+                   // Note that here we need both LHS and RHS to be
+                   // pointer. Then the inner matcher can match any of
+                   // them:
+                   allOf(hasLHS(hasPointerType()),
+                               hasRHS(hasPointerType())),
+                   eachOf(hasLHS(InnerMatcher),
+                                hasRHS(InnerMatcher)));
 
   auto CompOperandMatcher =
       binaryOperator(hasAnyOperatorName("!=", "==", "<", "<=", ">", ">="),
                      eachOf(hasLHS(allOf(hasPointerType(), InnerMatcher)),
                             hasRHS(allOf(hasPointerType(), InnerMatcher))));
 
-  return stmt(anyOf(CallArgMatcher, CastOperandMatcher, CompOperandMatcher));
+  return stmt(anyOf(CallArgMatcher, CastOperandMatcher, CompOperandMatcher, PtrSubtractionMatcher));
   // FIXME: any more cases? (UPC excludes the RHS of an assignment.  For now we
   // don't have to check that.)
 }
Index: clang/test/SemaCXX/warn-unsafe-buffer-usage-fixits-addressof-arraysubscript.cpp
===================================================================
--- clang/test/SemaCXX/warn-unsafe-buffer-usage-fixits-addressof-arraysubscript.cpp
+++ clang/test/SemaCXX/warn-unsafe-buffer-usage-fixits-addressof-arraysubscript.cpp
@@ -13,6 +13,24 @@
   // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:37-[[@LINE-1]]:42}:"&p.data()[x]"
 }
 
+void address_to_bool(int x) {
+  int * p = new int[10];
+  bool a = (bool) &p[5];
+  // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:19-[[@LINE-1]]:24}:"&p.data()[5]"
+  bool b = (bool) &p[x];
+  // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:19-[[@LINE-1]]:24}:"&p.data()[x]"
+
+  bool a1 = &p[5];
+  // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:13-[[@LINE-1]]:18}:"&p.data()[5]"
+  bool b1 = &p[x];
+  // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:13-[[@LINE-1]]:18}:"&p.data()[x]"
+
+  if (&p[5]) {
+    // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:7-[[@LINE-1]]:12}:"&p.data()[5]"
+    return;
+  }
+}
+
 void call_argument(int x) {
   int * p = new int[10];
 
@@ -55,9 +73,26 @@
   // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:5-[[@LINE-1]]:10}:"p.data()"
 }
 
-// CHECK-NOT: fix-it
+void pointer_subtraction(int x) {
+  int * p = new int[10];
+  // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:3-[[@LINE-1]]:12}:"std::span<int> p"
+  // CHECK: fix-it:"{{.*}}":{[[@LINE-2]]:13-[[@LINE-2]]:13}:"{"
+  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:24-[[@LINE-3]]:24}:", 10}"
+
+  int n = &p[9] - &p[4];
+  // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:11-[[@LINE-1]]:16}:"&p.data()[9]"
+  // CHECK: fix-it:"{{.*}}":{[[@LINE-2]]:19-[[@LINE-2]]:24}:"&p.data()[4]"
+  if (&p[9] - &p[x]) {
+    // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:7-[[@LINE-1]]:12}:"&p.data()[9]"
+    // CHECK: fix-it:"{{.*}}":{[[@LINE-2]]:15-[[@LINE-2]]:20}:"&p.data()[x]"
+    return;
+  }
+}
+
 // To test multiple function declarations, each of which carries
-// different incomplete informations:
+// different incomplete informations.
+// no fix-it in the rest of this test:
+
 [[clang::unsafe_buffer_usage]]
 void unsafe_g(void*);
 
@@ -65,8 +100,9 @@
 
 void multiple_unsafe_fundecls() {
   int * p = new int[10];
-
+  // CHECK-NOT: fix-it:"{{.*}}":{[[@LINE-1]]
   unsafe_g(&p[5]);
+  // CHECK-NOT: fix-it:"{{.*}}":{[[@LINE-1]]
 }
 
 void unsafe_h(void*);
@@ -78,6 +114,7 @@
 
 void multiple_unsafe_fundecls2() {
   int * p = new int[10];
-
+  // CHECK-NOT: fix-it:"{{.*}}":{[[@LINE-1]]
   unsafe_h(&p[5]);
+  // CHECK-NOT: fix-it:"{{.*}}":{[[@LINE-1]]
 }