[PATCH] D48717: [clang-tidy] fix PR36489 - respect deduced pointer types from auto as well

[Jonas Toth via Phabricator via cfe-commits]

JonasToth created this revision.
JonasToth added reviewers: alexfh, aaron.ballman, hokein, ilya-biryukov.
Herald added subscribers: cfe-commits, kbarton, xazax.hun, nemanjai.

The cppcoreguidelines-pro-bounds-pointer-arithmetic warns on all occassion where
pointer arithmetic is used, but does not check values where the pointer types
is deduced via ``auto``. This patch adjusts this behaviour and solved
PR36489.


Repository:
  rCTE Clang Tools Extra

https://reviews.llvm.org/D48717

Files:
  clang-tidy/cppcoreguidelines/ProBoundsPointerArithmeticCheck.cpp
  test/clang-tidy/cppcoreguidelines-pro-bounds-pointer-arithmetic-pr36489.cpp
  test/clang-tidy/cppcoreguidelines-pro-bounds-pointer-arithmetic.cpp


Index: test/clang-tidy/cppcoreguidelines-pro-bounds-pointer-arithmetic.cpp
===================================================================
--- test/clang-tidy/cppcoreguidelines-pro-bounds-pointer-arithmetic.cpp
+++ test/clang-tidy/cppcoreguidelines-pro-bounds-pointer-arithmetic.cpp
@@ -85,5 +85,5 @@
 
   auto diff = p - q; // OK, result is arithmetic
 
-  for(int ii : a) ; // OK, pointer arithmetic generated by compiler
+  for (int ii : a) ; // OK, pointer arithmetic generated by compiler
 }
Index: test/clang-tidy/cppcoreguidelines-pro-bounds-pointer-arithmetic-pr36489.cpp
===================================================================
--- /dev/null
+++ test/clang-tidy/cppcoreguidelines-pro-bounds-pointer-arithmetic-pr36489.cpp
@@ -0,0 +1,39 @@
+// RUN: %check_clang_tidy %s cppcoreguidelines-pro-bounds-pointer-arithmetic %t -- -- -std=c++14
+
+
+// Fix PR36489 and detect auto-deduced value correctly.
+char *getPtr();
+auto getPtrAuto() { return getPtr(); }
+auto getPtrWithTrailingReturnType() -> char *;
+
+void auto_deduction_binary() {
+  auto p1 = getPtr() + 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:22: warning: do not use pointer arithmetic
+  auto p2 = getPtrAuto() + 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:26: warning: do not use pointer arithmetic
+  auto p3 = getPtrWithTrailingReturnType() + 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:44: warning: do not use pointer arithmetic
+  auto p4 = getPtr();
+  auto *p5 = getPtr();
+  p4 = p4 + 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:11: warning: do not use pointer arithmetic
+  p5 = p5 + 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:11: warning: do not use pointer arithmetic
+}
+
+void auto_deduction_subscript() {
+  char p1 = getPtr()[2];
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: do not use pointer arithmetic
+  auto p2 = getPtr()[3];
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: do not use pointer arithmetic
+
+  char p3 = getPtrAuto()[4];
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: do not use pointer arithmetic
+  auto p4 = getPtrAuto()[5];
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: do not use pointer arithmetic
+
+  char p5 = getPtrWithTrailingReturnType()[6];
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: do not use pointer arithmetic
+  auto p6 = getPtrWithTrailingReturnType()[7];
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: do not use pointer arithmetic
+}
Index: clang-tidy/cppcoreguidelines/ProBoundsPointerArithmeticCheck.cpp
===================================================================
--- clang-tidy/cppcoreguidelines/ProBoundsPointerArithmeticCheck.cpp
+++ clang-tidy/cppcoreguidelines/ProBoundsPointerArithmeticCheck.cpp
@@ -21,12 +21,15 @@
   if (!getLangOpts().CPlusPlus)
     return;
 
+  const auto AllPointerTypes = anyOf(
+      hasType(pointerType()), hasType(autoType(hasDeducedType(pointerType()))));
+
   // Flag all operators +, -, +=, -=, ++, -- that result in a pointer
   Finder->addMatcher(
       binaryOperator(
           anyOf(hasOperatorName("+"), hasOperatorName("-"),
                 hasOperatorName("+="), hasOperatorName("-=")),
-          hasType(pointerType()),
+          AllPointerTypes,
           unless(hasLHS(ignoringImpCasts(declRefExpr(to(isImplicit()))))))
           .bind("expr"),
       this);
@@ -41,7 +44,7 @@
   Finder->addMatcher(
       arraySubscriptExpr(
           hasBase(ignoringImpCasts(
-              anyOf(hasType(pointerType()),
+              anyOf(AllPointerTypes,
                     hasType(decayedType(hasDecayedType(pointerType())))))))
           .bind("expr"),
       this);


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