1 files changed, 23 insertions, 4 deletions
diff --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsArrayToPointerDecayCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsArrayToPointerDecayCheck.cpp
index bfcef89e6bb..4977c2d7ed7 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsArrayToPointerDecayCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsArrayToPointerDecayCheck.cpp
@@ -47,6 +47,25 @@ AST_MATCHER_P(Expr, hasParentIgnoringImpCasts,
   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;
@@ -56,10 +75,12 @@ void ProBoundsArrayToPointerDecayCheck::registerMatchers(MatchFinder *Finder) {
   // 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);
 }
@@ -67,8 +88,6 @@ void ProBoundsArrayToPointerDecayCheck::registerMatchers(MatchFinder *Finder) {
 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 "