[LLDB] Support exception breakpoints for plugin-provided languages (#97675)

CommandObjectBreakpoint has a harcoded list of languages for which
exception breakpoints can be enabled. I'm making this a bit more generic
so that my Mojo plugin can get this feature.
Basically, I'm adding a new overridable method
`Language::SupportsExceptionBreakpoints` that can be used by language
plugins to determine whether they support this feature or not. This
method is used in addition to the hardcoded list and, as an example, I'm
using it for the ObjC language support.

Another route is simply to avoid doing the check that it's being done
right now and simply try to the create the exception breakpoint for
whatever language that is not in the hardcoded list. I'm happy to do
that if the reviewers think it's a good idea.

As a note, the other possible place for adding this
`SupportsExceptionBreakpoints` method is in `LanguageRuntime`. However,
accessing it requires having a process, which is not always the case
when invoking the `breakpoint set -E` command. The process might not be
alive yet, so `Language` is a good second place for this.

And as a final note, I don't want to make this
`SupportsExceptionBreakpoints` complicated. I'm keeping it as simple as
possible because it can easily evolve as it's not part of the public
API.

Author: walter-erquinigo

lldb/include/lldb/Target/Language.h

@@ -363,6 +363,10 @@ class Language : public PluginInterface {
     return false;
   }
 
+  /// Returns true if this Language supports exception breakpoints via a
+  /// corresponding LanguageRuntime plugin.
+  virtual bool SupportsExceptionBreakpoints() const { return false; }
+
 protected:
   // Classes that inherit from Language can see and modify these
 

lldb/source/Commands/CommandObjectBreakpoint.cpp

@@ -308,9 +308,6 @@ class CommandObjectBreakpointSet : public CommandObjectParsed {
         case eLanguageTypeC_plus_plus_14:
           m_exception_language = eLanguageTypeC_plus_plus;
           break;
-        case eLanguageTypeObjC:
-          m_exception_language = eLanguageTypeObjC;
-          break;
         case eLanguageTypeObjC_plus_plus:
           error_context =
               "Set exception breakpoints separately for c++ and objective-c";
@@ -319,6 +316,12 @@ class CommandObjectBreakpointSet : public CommandObjectParsed {
           error_context = "Unknown language type for exception breakpoint";
           break;
         default:
+          if (Language *languagePlugin = Language::FindPlugin(language)) {
+            if (languagePlugin->SupportsExceptionBreakpoints()) {
+              m_exception_language = language;
+              break;
+            }
+          }
           error_context = "Unsupported language type for exception breakpoint";
         }
         if (!error_context.empty())

lldb/source/Plugins/Language/ObjC/ObjCLanguage.h

@@ -194,6 +194,8 @@ class ObjCLanguage : public Language {
 
   llvm::StringRef GetInstanceVariableName() override { return "self"; }
 
+  bool SupportsExceptionBreakpoints() const override { return true; }
+
   // PluginInterface protocol
   llvm::StringRef GetPluginName() override { return GetPluginNameStatic(); }
 };