[lldb][NFC] Return a reference from ClangASTContext::getASTContext and remove dead nullptr checks

ClangASTContext::getASTContext() currently returns a ptr but we have an assert there since a
while that the ASTContext is not a nullptr. This causes that we still have a lot of code
that is doing nullptr checks on the result of getASTContext() which is all unreachable code.

This patch changes the return value to a reference to make it clear this can't be a nullptr
and deletes all the nullptr checks.

3 files changed, 13 insertions, 34 deletions

diff --git a/lldb/source/Plugins/ExpressionParser/Clang/ASTResultSynthesizer.cpp b/lldb/source/Plugins/ExpressionParser/Clang/ASTResultSynthesizer.cpp
index 6d6830c740d..1caac9e11cb 100644
--- a/lldb/source/Plugins/ExpressionParser/Clang/ASTResultSynthesizer.cpp
+++ b/lldb/source/Plugins/ExpressionParser/Clang/ASTResultSynthesizer.cpp
@@ -453,7 +453,7 @@ void ASTResultSynthesizer::CommitPersistentDecls() {
     ConstString name_cs(name.str().c_str());
 
     Decl *D_scratch = m_target.GetClangASTImporter()->DeportDecl(
-        ClangASTContext::GetScratch(m_target)->getASTContext(), decl);
+        &ClangASTContext::GetScratch(m_target)->getASTContext(), decl);
 
     if (!D_scratch) {
       Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_EXPRESSIONS));
diff --git a/lldb/source/Plugins/ExpressionParser/Clang/ClangASTSource.cpp b/lldb/source/Plugins/ExpressionParser/Clang/ClangASTSource.cpp
index e044a4d33b4..ff86f9f818b 100644
--- a/lldb/source/Plugins/ExpressionParser/Clang/ClangASTSource.cpp
+++ b/lldb/source/Plugins/ExpressionParser/Clang/ClangASTSource.cpp
@@ -57,7 +57,7 @@ ClangASTSource::ClangASTSource(const lldb::TargetSP &target,
 }
 
 void ClangASTSource::InstallASTContext(ClangASTContext &clang_ast_context) {
-  m_ast_context = clang_ast_context.getASTContext();
+  m_ast_context = &clang_ast_context.getASTContext();
   m_clang_ast_context = &clang_ast_context;
   m_file_manager = &m_ast_context->getSourceManager().getFileManager();
   m_ast_importer_sp->InstallMapCompleter(m_ast_context, *this);
@@ -80,14 +80,11 @@ ClangASTSource::~ClangASTSource() {
   if (!scratch_clang_ast_context)
     return;
 
-  clang::ASTContext *scratch_ast_context =
+  clang::ASTContext &scratch_ast_context =
       scratch_clang_ast_context->getASTContext();
 
-  if (!scratch_ast_context)
-    return;
-
-  if (m_ast_context != scratch_ast_context && m_ast_importer_sp)
-    m_ast_importer_sp->ForgetSource(scratch_ast_context, m_ast_context);
+  if (m_ast_context != &scratch_ast_context && m_ast_importer_sp)
+    m_ast_importer_sp->ForgetSource(&scratch_ast_context, m_ast_context);
 }
 
 void ClangASTSource::StartTranslationUnit(ASTConsumer *Consumer) {
@@ -1880,10 +1877,10 @@ clang::NamedDecl *NameSearchContext::AddVarDecl(const CompilerType &type) {
 
   IdentifierInfo *ii = m_decl_name.getAsIdentifierInfo();
 
-  clang::ASTContext *ast = lldb_ast->getASTContext();
+  clang::ASTContext &ast = lldb_ast->getASTContext();
 
   clang::NamedDecl *Decl = VarDecl::Create(
-      *ast, const_cast<DeclContext *>(m_decl_context), SourceLocation(),
+      ast, const_cast<DeclContext *>(m_decl_context), SourceLocation(),
       SourceLocation(), ii, ClangUtil::GetQualType(type), nullptr, SC_Static);
   m_decls.push_back(Decl);
 
@@ -1909,7 +1906,7 @@ clang::NamedDecl *NameSearchContext::AddFunDecl(const CompilerType &type,
 
   QualType qual_type(ClangUtil::GetQualType(type));
 
-  clang::ASTContext *ast = lldb_ast->getASTContext();
+  clang::ASTContext &ast = lldb_ast->getASTContext();
 
   const bool isInlineSpecified = false;
   const bool hasWrittenPrototype = true;
@@ -1919,7 +1916,7 @@ clang::NamedDecl *NameSearchContext::AddFunDecl(const CompilerType &type,
 
   if (extern_c) {
     context = LinkageSpecDecl::Create(
-        *ast, context, SourceLocation(), SourceLocation(),
+        ast, context, SourceLocation(), SourceLocation(),
         clang::LinkageSpecDecl::LanguageIDs::lang_c, false);
   }
 
@@ -1931,7 +1928,7 @@ clang::NamedDecl *NameSearchContext::AddFunDecl(const CompilerType &type,
           : m_decl_name;
 
   clang::FunctionDecl *func_decl = FunctionDecl::Create(
-      *ast, context, SourceLocation(), SourceLocation(), decl_name, qual_type,
+      ast, context, SourceLocation(), SourceLocation(), decl_name, qual_type,
       nullptr, SC_Extern, isInlineSpecified, hasWrittenPrototype,
       isConstexprSpecified ? CSK_constexpr : CSK_unspecified);
 
@@ -1952,7 +1949,7 @@ clang::NamedDecl *NameSearchContext::AddFunDecl(const CompilerType &type,
       QualType arg_qual_type(func_proto_type->getParamType(ArgIndex));
 
       parm_var_decls.push_back(
-          ParmVarDecl::Create(*ast, const_cast<DeclContext *>(context),
+          ParmVarDecl::Create(ast, const_cast<DeclContext *>(context),
                               SourceLocation(), SourceLocation(), nullptr,
                               arg_qual_type, nullptr, SC_Static, nullptr));
     }
diff --git a/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionDeclMap.cpp b/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionDeclMap.cpp
index 23202766892..e9ba1bffd34 100644
--- a/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionDeclMap.cpp
+++ b/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionDeclMap.cpp
@@ -179,7 +179,7 @@ TypeFromUser ClangExpressionDeclMap::DeportType(ClangASTContext &target,
                                                 TypeFromParser parser_type) {
   assert(&target == ClangASTContext::GetScratch(*m_target));
   assert((TypeSystem *)&source == parser_type.GetTypeSystem());
-  assert(source.getASTContext() == m_ast_context);
+  assert(&source.getASTContext() == m_ast_context);
 
   if (m_ast_importer_sp) {
     return TypeFromUser(m_ast_importer_sp->DeportType(target, parser_type));
@@ -741,16 +741,7 @@ clang::NamedDecl *ClangExpressionDeclMap::GetPersistentDecl(ConstString name) {
   if (!target)
     return nullptr;
 
-  ClangASTContext *scratch_clang_ast_context =
-      ClangASTContext::GetScratch(*target);
-
-  if (!scratch_clang_ast_context)
-    return nullptr;
-
-  ASTContext *scratch_ast_context = scratch_clang_ast_context->getASTContext();
-
-  if (!scratch_ast_context)
-    return nullptr;
+  ClangASTContext::GetScratch(*target);
 
   return m_parser_vars->m_persistent_vars->GetPersistentDecl(name);
 }
@@ -1528,15 +1519,6 @@ bool ClangExpressionDeclMap::GetVariableValue(VariableSP &var,
     return false;
   }
 
-  ASTContext *ast = clang_ast->getASTContext();
-
-  if (!ast) {
-    if (log)
-      log->PutCString(
-          "There is no AST context for the current execution context");
-    return false;
-  }
-
   DWARFExpression &var_location_expr = var->LocationExpression();
 
   Target *target = m_parser_vars->m_exe_ctx.GetTargetPtr();