[PATCH] D138329: [-Wunsafe-buffer-usage] Add a new recursive matcher to replace `forEachDescendant` in unsafe buffer check

[Ziqing Luo via Phabricator via cfe-commits]

ziqingluo-90 added inline comments.


================
Comment at: clang/lib/Analysis/UnsafeBufferUsage.cpp:54-55
+  bool TraverseDecl(Decl *Node) {
+    if (!Node)
+      return true;
+    if (!match(*Node))
----------------
NoQ wrote:
> ziqingluo-90 wrote:
> > steakhal wrote:
> > > Can `Node` be ever null if the visitor is initiated only be `AST_MATCHER_P`?
> > Honestly I do not know the exact answer to your question.  I was imagining that an AST node could have a null to be one of its children.
> > 
> > Our plan later is to make this matcher a general alternative to `forEachDescendant`, so I think the check for null here is not over-defensive.
> There can definitely be null children in the AST. Eg. `for(;;) {}` has null initializer, null condition, null increment, non-null body. I guess this is more about whether `RecursiveASTVisitor` checks for that automatically before invoking callbacks.
>  I guess this is more about whether RecursiveASTVisitor checks for that automatically before invoking callbacks.

The override-ed `TraverseDecl` method in the base class `RecursiveASTVisitor` also has a null-check. So I feel like this null-check is needed here.


================
Comment at: clang/lib/Analysis/UnsafeBufferUsage.cpp:59
+    // To skip callables:
+    if (llvm::isa<FunctionDecl, BlockDecl, ObjCMethodDecl>(Node))
+      return true;
----------------
NoQ wrote:
> `llvm::` is unnecessary, we're under `using namespace llvm`.



================
Comment at: clang/lib/Analysis/UnsafeBufferUsage.cpp:71
+    // To skip callables:
+    if (llvm::isa<LambdaExpr>(Node))
+      return true;
----------------



Repository:
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  https://reviews.llvm.org/D138329/new/

https://reviews.llvm.org/D138329