[Clang][NFC] Add nullptr check in InitializationSequence::InitializeFrom

[shafik]

Static analysis flagged that Var could be nullptr but we were not checking in the branch and unconditionally dereferences the pointer.

Note, code was added by 576161c

[llvmbot]

@llvm/pr-subscribers-clang

Author: Shafik Yaghmour (shafik)

Changes

Static analysis flagged that Var could be nullptr but we were not checking in the branch and unconditionally dereferences the pointer.

Note, code was added by 576161c

---

Full diff: https://github.com/llvm/llvm-project/pull/143067.diff

1 Files Affected:

• (modified) clang/lib/Sema/SemaInit.cpp (+1-1)

diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
index 5d870f07093ec..da56225b2f926 100644
--- a/clang/lib/Sema/SemaInit.cpp
+++ b/clang/lib/Sema/SemaInit.cpp
@@ -6620,7 +6620,7 @@ void InitializationSequence::InitializeFrom(Sema &S,
       // initializer present. However, we only do this for structure types, not
       // union types, because an unitialized field in a union is generally
       // reasonable, especially in C where unions can be used for type punning.
-      if (!Initializer && !Rec->isUnion() && !Rec->isInvalidDecl()) {
+      if (Var && !Initializer && !Rec->isUnion() && !Rec->isInvalidDecl()) {
         if (const FieldDecl *FD = getConstField(Rec)) {
           unsigned DiagID = diag::warn_default_init_const_field_unsafe;
           if (Var->getStorageDuration() == SD_Static ||

[cor3ntin]

If this were a bug, I suspect it would have been reported.
Most likely, dyn_cast_or_null<VarDecl>(Entity.getDecl()); is never null, and could be replaced by cast? Did you try that?

[shafik]

If this were a bug, I suspect it would have been reported. Most likely, dyn_cast_or_null<VarDecl>(Entity.getDecl()); is never null, and could be replaced by cast? Did you try that?

It could but that feel like a weak argument, I would like something stronger.

We do dyn_cast_or_null<VarDecl>(...->getDecl()) in a lot of place, maybe it is cargo culting and it is not needed but I can't really tell.

[AaronBallman]

If this were a bug, I suspect it would have been reported. Most likely, dyn_cast_or_null<VarDecl>(Entity.getDecl()); is never null, and could be replaced by cast? Did you try that?

getDecl() can definitely return null:

llvm-project/clang/lib/Sema/SemaInit.cpp

Line 3728 in e4060d3

return nullptr;

[AaronBallman]

LGTM