[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

[Fangrui Song via cfe-commits]

================
@@ -1,11 +1,20 @@
 // RUN: %clang -### -S -fwrapv -fno-wrapv -fwrapv %s 2>&1 | FileCheck -check-prefix=CHECK1 %s
 // CHECK1: -fwrapv
 //
+// RUN: %clang -### -S -fwrapv-pointer -fno-wrapv-pointer -fwrapv-pointer %s 2>&1 | FileCheck -check-prefix=CHECK1-POINTER %s
+// CHECK1-POINTER: -fwrapv-pointer
+//
 // RUN: %clang -### -S -fstrict-overflow -fno-strict-overflow %s 2>&1 | FileCheck -check-prefix=CHECK2 %s
-// CHECK2: -fwrapv
+// CHECK2: -fwrapv{{.*}}-fwrapv-pointer
 //
-// RUN: %clang -### -S -fwrapv -fstrict-overflow %s 2>&1 | FileCheck -check-prefix=CHECK3 %s
+// RUN: %clang -### -S -fwrapv -fstrict-overflow %s 2>&1 | FileCheck -check-prefix=CHECK3 %s --implicit-check-not="-fwrapv-pointer"
 // CHECK3: -fwrapv
 //
-// RUN: %clang -### -S -fno-wrapv -fno-strict-overflow %s 2>&1 | FileCheck -check-prefix=CHECK4 %s
-// CHECK4-NOT: -fwrapv
+// RUN: %clang -### -S -fwrapv-pointer -fstrict-overflow %s 2>&1 | FileCheck -check-prefix=CHECK3-POINTER %s --implicit-check-not="-fwrapv"
+// CHECK3-POINTER: -fwrapv-pointer
+//
+// RUN: %clang -### -S -fno-wrapv -fno-strict-overflow %s 2>&1 | FileCheck -check-prefix=CHECK4 %s --implicit-check-not="-fwrapv"
+// CHECK4: -fwrapv-pointer
+//
+// RUN: %clang -### -S -fno-wrapv-pointer -fno-strict-overflow %s 2>&1 | FileCheck -check-prefix=CHECK4-POINTER %s --implicit-check-not="-fwrapv-pointer"
+// CHECK4-POINTER: -fwrapv
----------------
MaskRay wrote:

You might need `"-fwrapv"`. Otherwise, IIUC even if the output is `-fwrap-pointer`, the check will pass. Because `-fwrapv` matches, and the remaining string will pass the --implicit-check-not check.

https://github.com/llvm/llvm-project/pull/122486