Fix cppcoreguidelines-pro-bounds-pointer-arithmetic not working for functions with auto return specifier.

[predator5047]

Summary

Fix bug #36489

[aaron.ballman]

Some minor formatting nits, but otherwise LGTM. You should run the patch through clang-format: https://clang.llvm.org/docs/ClangFormat.html#script-for-patch-reformatting

clang-tidy/cppcoreguidelines/ProBoundsPointerArithmeticCheck.cpp

29

This extends past the 80-col limit.

test/clang-tidy/cppcoreguidelines-pro-bounds-pointer-arithmetic.cpp

12

Should be int * instead of int* (elsewhere as well).

26

Can you remove the whitespace alignment from the new tests?

[mgehre]

Does it also work with lambdas (being implicitly auto) that return pointers? A test case for that would be nice.

clang-tidy/cppcoreguidelines/ProBoundsPointerArithmeticCheck.cpp

void ProBoundsPointerArithmeticCheck::registerMatchers(MatchFinder *Finder) {
   if (!getLangOpts().CPlusPlus)
     return;
 
   // Flag all operators +, -, +=, -=, ++, -- that result in a pointer
   Finder->addMatcher(
       binaryOperator(
           anyOf(hasOperatorName("+"), hasOperatorName("-"),
                 hasOperatorName("+="), hasOperatorName("-=")),
-          hasType(pointerType()),
+          anyOf(hasType(pointerType()), hasType(autoType(hasDeducedType(pointerType())))),
           unless(hasLHS(ignoringImpCasts(declRefExpr(to(isImplicit()))))))
           .bind("expr"),
       this);
 
   Finder->addMatcher(
       unaryOperator(anyOf(hasOperatorName("++"), hasOperatorName("--")),
                     hasType(pointerType()))
           .bind("expr"),

test/clang-tidy/cppcoreguidelines-pro-bounds-pointer-arithmetic.cpp

-// RUN: %check_clang_tidy %s cppcoreguidelines-pro-bounds-pointer-arithmetic %t
+// RUN: %check_clang_tidy %s cppcoreguidelines-pro-bounds-pointer-arithmetic %t -- -- -std=c++14
 
 enum E {
   ENUM_LITERAL = 1
 };
 
 int i = 4;
 int j = 1;
 int *p = 0;
 int *q = 0;
 
+int* pointer() {
+  return nullptr;
+}
+
+auto pointerAuto() {
+  return (int*) nullptr;
+}
+
+auto pointerAutoTrailing() -> int* {
+  return (int*) nullptr;
+}
+
 void fail() {
+  auto x = (int*) nullptr;
+  p = x                     + 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: do not use pointer arithmetic
+  p = pointer()             + 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: do not use pointer arithmetic
+  p = pointerAuto()         + 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: do not use pointer arithmetic
+  p = pointerAutoTrailing() + 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: do not use pointer arithmetic
+
+  p = 1                     + pointer();
+  // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: do not use pointer arithmetic
+  p = 1                     + pointerAuto();
+  // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: do not use pointer arithmetic
+  p = 1                     + pointerAutoTrailing();
+  // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: do not use pointer arithmetic
+
   q = p + 4;
   // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: do not use pointer arithmetic [cppcoreguidelines-pro-bounds-pointer-arithmetic]
   p = q + i;
   // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: do not use pointer arithmetic
   p = q + ENUM_LITERAL;
   // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: do not use pointer arithmetic
 
   q = p - 1;