[lldb] Support specifying a language for breakpoint conditions (#147603)

LLDB breakpoint conditions take an expression that's evaluated using the
language of the code where the breakpoint is located. Users have asked
to have an option to tell it to evaluate the expression in a specific
language.

This is feature is especially helpful for Swift, for example for a
condition based on the value in memory at an offset from a register.
Such a condition is pretty difficult to write in Swift, but easy in C.

This PR adds a new argument (-Y) to specify the language of the
condition expression. We can't reuse the current -L option, since you
might want to break on only Swift symbols, but run a C expression there
as per the example above.

rdar://146119507

1 files changed, 16 insertions, 1 deletions

diff --git a/lldb/source/Commands/CommandObjectBreakpoint.cpp b/lldb/source/Commands/CommandObjectBreakpoint.cpp
index 2440a7e..38ec375 100644
--- a/lldb/source/Commands/CommandObjectBreakpoint.cpp
+++ b/lldb/source/Commands/CommandObjectBreakpoint.cpp
@@ -72,7 +72,7 @@ public:
     case 'c':
       // Normally an empty breakpoint condition marks is as unset. But we need
       // to say it was passed in.
-      m_bp_opts.SetCondition(option_arg.str().c_str());
+      m_bp_opts.GetCondition().SetText(option_arg.str());
       m_bp_opts.m_set_flags.Set(BreakpointOptions::eCondition);
       break;
     case 'C':
@@ -154,6 +154,21 @@ public:
         m_bp_opts.GetThreadSpec()->SetIndex(thread_index);
       }
     } break;
+    case 'Y': {
+      LanguageType language = Language::GetLanguageTypeFromString(option_arg);
+
+      LanguageSet languages_for_expressions =
+          Language::GetLanguagesSupportingTypeSystemsForExpressions();
+      if (language == eLanguageTypeUnknown)
+        error = Status::FromError(CreateOptionParsingError(
+            option_arg, short_option, long_option, "invalid language"));
+      else if (!languages_for_expressions[language])
+        error = Status::FromError(
+            CreateOptionParsingError(option_arg, short_option, long_option,
+                                     "no expression support for language"));
+      else
+        m_bp_opts.GetCondition().SetLanguage(language);
+    } break;
     default:
       llvm_unreachable("Unimplemented option");
     }