[clang] [NFC][Clang] Fix potential dereferencing of nullptr (PR #86759)

[via cfe-commits]

https://github.com/smanna12 created https://github.com/llvm/llvm-project/pull/86759

This patch replaces dyn_cast<> with cast<> to resolve potential static analyzer bugs for

1. Dereferencing a pointer issue with nullptr GVar when calling addAttribute() in AIXTargetCodeGenInfo::setTargetAttributes(clang::Decl const *, llvm::GlobalValue *, clang::CodeGen::CodeGenModule &).

2. Dereferencing a pointer issue with nullptr GG when calling getCorrespondingConstructor() in DeclareImplicitDeductionGuidesForTypeAlias(clang::Sema &, clang::TypeAliasTemplateDecl *, clang::SourceLocation).

3. Dereferencing a pointer issue with nullptr CurrentBT when calling getKind() in ComplexExprEmitter::GetHigherPrecisionFPType(clang::QualType).

>From 1b0d28a8abc322753108d1771f4928cac96584ee Mon Sep 17 00:00:00 2001
From: "Manna, Soumi" <soumi.manna at intel.com>
Date: Tue, 26 Mar 2024 19:24:42 -0700
Subject: [PATCH] [NFC][Clang] Fix potential dereferencing of nullptr

This patch replaces dyn_cast<> with cast<> to resolve potential static
analyzer bugs for

1. Dereferencing a pointer issue with nullptr GVar when calling addAttribute()
   in AIXTargetCodeGenInfo::setTargetAttributes(clang::Decl const *, llvm::GlobalValue *, clang::CodeGen::CodeGenModule &).

2. Dereferencing a pointer issue with nullptr GG when calling getCorrespondingConstructor() in DeclareImplicitDeductionGuidesForTypeAlias(clang::Sema &, clang::TypeAliasTemplateDecl *, clang::SourceLocation).

3. Dereferencing a pointer issue with nullptr CurrentBT when calling
   getKind() in ComplexExprEmitter::GetHigherPrecisionFPType(clang::QualType).
---
 clang/lib/CodeGen/CGExprComplex.cpp | 2 +-
 clang/lib/CodeGen/Targets/PPC.cpp   | 2 +-
 clang/lib/Sema/SemaTemplate.cpp     | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/clang/lib/CodeGen/CGExprComplex.cpp b/clang/lib/CodeGen/CGExprComplex.cpp
index b873bc6737bb0a..c3774d0cb75edc 100644
--- a/clang/lib/CodeGen/CGExprComplex.cpp
+++ b/clang/lib/CodeGen/CGExprComplex.cpp
@@ -289,7 +289,7 @@ class ComplexExprEmitter
                                         const BinOpInfo &Op);
 
   QualType GetHigherPrecisionFPType(QualType ElementType) {
-    const auto *CurrentBT = dyn_cast<BuiltinType>(ElementType);
+    const auto *CurrentBT = cast<BuiltinType>(ElementType);
     switch (CurrentBT->getKind()) {
     case BuiltinType::Kind::Float16:
       return CGF.getContext().FloatTy;
diff --git a/clang/lib/CodeGen/Targets/PPC.cpp b/clang/lib/CodeGen/Targets/PPC.cpp
index 00b04723f17dd2..3eadb19bd2058f 100644
--- a/clang/lib/CodeGen/Targets/PPC.cpp
+++ b/clang/lib/CodeGen/Targets/PPC.cpp
@@ -274,7 +274,7 @@ void AIXTargetCodeGenInfo::setTargetAttributes(
   if (!isa<llvm::GlobalVariable>(GV))
     return;
 
-  auto *GVar = dyn_cast<llvm::GlobalVariable>(GV);
+  auto *GVar = cast<llvm::GlobalVariable>(GV);
   auto GVId = GV->getName();
 
   // Is this a global variable specified by the user as toc-data?
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 005529a53270c3..aab72dbaf48c46 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -2974,7 +2974,7 @@ void DeclareImplicitDeductionGuidesForTypeAlias(
     if (auto *FPrime = SemaRef.InstantiateFunctionDeclaration(
             F, TemplateArgListForBuildingFPrime, AliasTemplate->getLocation(),
             Sema::CodeSynthesisContext::BuildingDeductionGuides)) {
-      auto *GG = dyn_cast<CXXDeductionGuideDecl>(FPrime);
+      auto *GG = cast<CXXDeductionGuideDecl>(FPrime);
       buildDeductionGuide(SemaRef, AliasTemplate, FPrimeTemplateParamList,
                           GG->getCorrespondingConstructor(),
                           GG->getExplicitSpecifier(), GG->getTypeSourceInfo(),