[clang] [NFC][Clang] Fix potential dereferencing of nullptr (PR #85944)

[via cfe-commits]

https://github.com/smanna12 created https://github.com/llvm/llvm-project/pull/85944

This patch replaces getAs<> with castAs<> to resolve

1. Dereferencing a pointer issue with nullptr FPT when calling ResolveExceptionSpec() in checkEscapingByref(clang::VarDecl *, clang::Sema &).

2. Dereferencing a pointer issue with nullptr ElementTy->getAs() when calling getElementType() in clang::Sema::SemaBuiltinFPClassification(clang::CallExpr *, unsigned int).

3. Dereferencing a pointer issue with nullptr ConvType->getAs() when calling getKeyword() in clang::Sema::ActOnConversionDeclarator(clang::CXXConversionDecl *).

>From 060f862855f1ab9ff7f545ca0a159c83026b6f8f Mon Sep 17 00:00:00 2001
From: "Manna, Soumi" <soumi.manna at intel.com>
Date: Wed, 20 Mar 2024 08:06:51 -0700
Subject: [PATCH] [NFC][Clang] Fix potential dereferencing of nullptr

This patch replaces getAs<> with castAs<> to resolve

1. Dereferencing a pointer issue with nullptr FPT when calling ResolveExceptionSpec()
   in checkEscapingByref(clang::VarDecl *, clang::Sema &).

2. Dereferencing a pointer issue with nullptr ElementTy->getAs() when
   calling getElementType() in clang::Sema::SemaBuiltinFPClassification(clang::CallExpr *,
   unsigned int).

3. Dereferencing a pointer issue with nullptr ConvType->getAs() when calling getKeyword() in
   clang::Sema::ActOnConversionDeclarator(clang::CXXConversionDecl *).
---
 clang/lib/Sema/Sema.cpp         | 2 +-
 clang/lib/Sema/SemaChecking.cpp | 2 +-
 clang/lib/Sema/SemaDeclCXX.cpp  | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
index cd0c42d5ffbacd..ba03b4f50a195a 100644
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -2206,7 +2206,7 @@ static void checkEscapingByref(VarDecl *VD, Sema &S) {
   // block copy/destroy functions. Resolve it here.
   if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl())
     if (CXXDestructorDecl *DD = RD->getDestructor()) {
-      auto *FPT = DD->getType()->getAs<FunctionProtoType>();
+      auto *FPT = DD->getType()->castAs<FunctionProtoType>();
       S.ResolveExceptionSpec(Loc, FPT);
     }
 }
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index ef3ab16ba29b41..40b92a03afcaae 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -9647,7 +9647,7 @@ bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs,
   // vector argument can be supported in all of them.
   if (ElementTy->isVectorType() && IsFPClass) {
     VectorResultTy = GetSignedVectorType(ElementTy);
-    ElementTy = ElementTy->getAs<VectorType>()->getElementType();
+    ElementTy = ElementTy->castAs<VectorType>()->getElementType();
   }
 
   // This operation requires a non-_Complex floating-point number.
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index e258a4f7c89415..e2cefcb9099755 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -11352,7 +11352,7 @@ Decl *Sema::ActOnConversionDeclarator(CXXConversionDecl *Conversion) {
     if (ConvType->isUndeducedAutoType()) {
       Diag(Conversion->getTypeSpecStartLoc(), diag::err_auto_not_allowed)
           << getReturnTypeLoc(Conversion).getSourceRange()
-          << llvm::to_underlying(ConvType->getAs<AutoType>()->getKeyword())
+          << llvm::to_underlying(ConvType->castAs<AutoType>()->getKeyword())
           << /* in declaration of conversion function template= */ 24;
     }