[PATCH] D31130: B32239 clang-tidy should not warn about array to pointer decay on system macros

[Breno Rodrigues Guimaraes via Phabricator via cfe-commits]

brenoguim updated this revision to Diff 92419.
brenoguim added a comment.

- Using the ImplicitCastExpr type on the AST_MATCHER directly to avoid explicit cast.
- Using isa<> instead of dyn_cast<> to just check for type
- Move variable declaration into "if"  condition


https://reviews.llvm.org/D31130

Files:
  clang-tidy/cppcoreguidelines/ProBoundsArrayToPointerDecayCheck.cpp
  test/clang-tidy/cppcoreguidelines-pro-bounds-array-to-pointer-decay.cpp


Index: test/clang-tidy/cppcoreguidelines-pro-bounds-array-to-pointer-decay.cpp
===================================================================
--- test/clang-tidy/cppcoreguidelines-pro-bounds-array-to-pointer-decay.cpp
+++ test/clang-tidy/cppcoreguidelines-pro-bounds-array-to-pointer-decay.cpp
@@ -1,4 +1,5 @@
 // RUN: %check_clang_tidy %s cppcoreguidelines-pro-bounds-array-to-pointer-decay %t
+#include <assert.h>
 #include <stddef.h>
 
 namespace gsl {
@@ -34,6 +35,11 @@
 
   for (auto &e : a) // OK, iteration internally decays array to pointer
     e = 1;
+
+  assert(false); // OK, array decay inside system header macro
+
+  assert(a);
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: do not implicitly decay an array into a pointer; consider using gsl::array_view or an explicit cast instead [cppcoreguidelines-pro-bounds-array-to-pointer-decay]
 }
 
 const char *g() {
Index: clang-tidy/cppcoreguidelines/ProBoundsArrayToPointerDecayCheck.cpp
===================================================================
--- clang-tidy/cppcoreguidelines/ProBoundsArrayToPointerDecayCheck.cpp
+++ clang-tidy/cppcoreguidelines/ProBoundsArrayToPointerDecayCheck.cpp
@@ -47,6 +47,25 @@
   return InnerMatcher.matches(*E, Finder, Builder);
 }
 
+AST_MATCHER(ImplicitCastExpr, isArrayToPointerDecay) {
+  return Node.getCastKind() == CK_ArrayToPointerDecay;
+}
+
+AST_MATCHER(ImplicitCastExpr, sysSymbolDecayInSysHeader) {
+  auto &SM = Finder->getASTContext().getSourceManager();
+  if (SM.isInSystemMacro(Node.getLocStart())) {
+    if (isa<PredefinedExpr>(Node.getSubExpr()))
+      return true;
+
+    if (const auto *SymbolDeclRef = dyn_cast<DeclRefExpr>(Node.getSubExpr())) {
+      const ValueDecl *SymbolDecl = SymbolDeclRef->getDecl();
+      if (SymbolDecl && SM.isInSystemHeader(SymbolDecl->getLocation()))
+        return true;
+    }
+  }
+  return false;
+}
+
 void ProBoundsArrayToPointerDecayCheck::registerMatchers(MatchFinder *Finder) {
   if (!getLangOpts().CPlusPlus)
     return;
@@ -56,19 +75,19 @@
   // 2) inside a range-for over an array
   // 3) if it converts a string literal to a pointer
   Finder->addMatcher(
-      implicitCastExpr(unless(hasParent(arraySubscriptExpr())),
+      implicitCastExpr(isArrayToPointerDecay(),
+                       unless(hasParent(arraySubscriptExpr())),
                        unless(hasParentIgnoringImpCasts(explicitCastExpr())),
                        unless(isInsideOfRangeBeginEndStmt()),
-                       unless(hasSourceExpression(stringLiteral())))
+                       unless(hasSourceExpression(stringLiteral())),
+                       unless(sysSymbolDecayInSysHeader()))
           .bind("cast"),
       this);
 }
 
 void ProBoundsArrayToPointerDecayCheck::check(
     const MatchFinder::MatchResult &Result) {
   const auto *MatchedCast = Result.Nodes.getNodeAs<ImplicitCastExpr>("cast");
-  if (MatchedCast->getCastKind() != CK_ArrayToPointerDecay)
-    return;
 
   diag(MatchedCast->getExprLoc(), "do not implicitly decay an array into a "
                                   "pointer; consider using gsl::array_view or "


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