[lldb][Language] Change GetFunctionDisplayName to take SymbolContext by reference (llvm#135536)

Both the `CPlusPlusLanguage` plugins and the Swift language plugin
already assume the `sc != nullptr`. And all `FormatEntity` callsites of
`GetFunctionDisplayName` already check for nullptr before passing `sc`.
This patch makes this pre-condition explicit by changing the parameter
to `const SymbolContext &`. This will help with some upcoming changes in
this area.

(cherry picked from commit 52e45a7)

Author: Michael137

lldb/include/lldb/Target/Language.h

@@ -270,7 +270,7 @@ class Language : public PluginInterface {
   // the reference has never been assigned
   virtual bool IsUninitializedReference(ValueObject &valobj);
 
-  virtual bool GetFunctionDisplayName(const SymbolContext *sc,
+  virtual bool GetFunctionDisplayName(const SymbolContext &sc,
                                       const ExecutionContext *exe_ctx,
                                       FunctionNameRepresentation representation,
                                       Stream &s);

lldb/source/Core/FormatEntity.cpp

@@ -1729,7 +1729,7 @@ bool FormatEntity::Format(const Entry &entry, Stream &s,
 
     if (language_plugin)
       language_plugin_handled = language_plugin->GetFunctionDisplayName(
-          sc, exe_ctx, Language::FunctionNameRepresentation::eName, ss);
+          *sc, exe_ctx, Language::FunctionNameRepresentation::eName, ss);
 
     if (language_plugin_handled) {
       s << ss.GetString();
@@ -1764,7 +1764,7 @@ bool FormatEntity::Format(const Entry &entry, Stream &s,
 
     if (language_plugin)
       language_plugin_handled = language_plugin->GetFunctionDisplayName(
-          sc, exe_ctx, Language::FunctionNameRepresentation::eNameWithNoArgs,
+          *sc, exe_ctx, Language::FunctionNameRepresentation::eNameWithNoArgs,
           ss);
 
     if (language_plugin_handled) {
@@ -1799,7 +1799,8 @@ bool FormatEntity::Format(const Entry &entry, Stream &s,
 
     if (language_plugin)
       language_plugin_handled = language_plugin->GetFunctionDisplayName(
-          sc, exe_ctx, Language::FunctionNameRepresentation::eNameWithArgs, ss);
+          *sc, exe_ctx, Language::FunctionNameRepresentation::eNameWithArgs,
+          ss);
 
     if (language_plugin_handled) {
       s << ss.GetString();

lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp

@@ -1759,20 +1759,18 @@ static bool PrintFunctionNameWithArgs(Stream &s,
 }
 
 bool CPlusPlusLanguage::GetFunctionDisplayName(
-    const SymbolContext *sc, const ExecutionContext *exe_ctx,
+    const SymbolContext &sc, const ExecutionContext *exe_ctx,
     FunctionNameRepresentation representation, Stream &s) {
   switch (representation) {
   case FunctionNameRepresentation::eNameWithArgs: {
-    assert(sc);
-
     // Print the function name with arguments in it
-    if (sc->function)
-      return PrintFunctionNameWithArgs(s, exe_ctx, *sc);
+    if (sc.function)
+      return PrintFunctionNameWithArgs(s, exe_ctx, sc);
 
-    if (!sc->symbol)
+    if (!sc.symbol)
       return false;
 
-    const char *cstr = sc->symbol->GetName().AsCString(nullptr);
+    const char *cstr = sc.symbol->GetName().AsCString(nullptr);
     if (!cstr)
       return false;
 

lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.h

@@ -138,7 +138,7 @@ class CPlusPlusLanguage : public Language {
   ConstString
   GetDemangledFunctionNameWithoutArguments(Mangled mangled) const override;
 
-  bool GetFunctionDisplayName(const SymbolContext *sc,
+  bool GetFunctionDisplayName(const SymbolContext &sc,
                               const ExecutionContext *exe_ctx,
                               FunctionNameRepresentation representation,
                               Stream &s) override;

lldb/source/Target/Language.cpp

@@ -510,7 +510,7 @@ bool Language::IsNilReference(ValueObject &valobj) { return false; }
 
 bool Language::IsUninitializedReference(ValueObject &valobj) { return false; }
 
-bool Language::GetFunctionDisplayName(const SymbolContext *sc,
+bool Language::GetFunctionDisplayName(const SymbolContext &sc,
                                       const ExecutionContext *exe_ctx,
                                       FunctionNameRepresentation representation,
                                       Stream &s) {