Add a new SBExpressionOptions::SetLanguage() API (NFCI)

that separates out language and version. To avoid reinventing the
wheel and introducing subtle incompatibilities, this API uses the
table of languages and versiond defined by the upcoming DWARF 6
standard (https://dwarfstd.org/languages-v6.html). While the DWARF 6
spec is not finialized, the list of languages is broadly considered
stable.

The primary motivation for this is to allow the Swift language plugin
to switch between language dialects between, e.g., Swift 5.9 and 6.0
with out introducing a ton of new language codes. On the main branch
this change is considered NFC.

Author: adrian-prantl

lldb/include/lldb/API/SBExpressionOptions.h

@@ -10,6 +10,7 @@
 #define LLDB_API_SBEXPRESSIONOPTIONS_H
 
 #include "lldb/API/SBDefines.h"
+#include "lldb/API/SBLanguages.h"
 
 #include <vector>
 
@@ -67,6 +68,10 @@ class LLDB_API SBExpressionOptions {
   void SetTrapExceptions(bool trap_exceptions = true);
 
   void SetLanguage(lldb::LanguageType language);
+  /// Set the language using a pair of language code and version as
+  /// defined by the DWARF 6 specification.
+  /// WARNING: These codes may change until DWARF 6 is finalized.
+  void SetLanguage(SBSourceLanguageName name, uint32_t version);
 
 #ifndef SWIG
   void SetCancelCallback(lldb::ExpressionCancelCallback callback, void *baton);

lldb/include/lldb/Expression/Expression.h

@@ -47,11 +47,8 @@ class Expression {
   /// expression.  Text() should contain the definition of this function.
   virtual const char *FunctionName() = 0;
 
-  /// Return the language that should be used when parsing.  To use the
-  /// default, return eLanguageTypeUnknown.
-  virtual lldb::LanguageType Language() const {
-    return lldb::eLanguageTypeUnknown;
-  }
+  /// Return the language that should be used when parsing.
+  virtual SourceLanguage Language() const { return {}; }
 
   /// Return the Materializer that the parser should use when registering
   /// external values.

lldb/include/lldb/Expression/LLVMUserExpression.h

@@ -52,7 +52,7 @@ class LLVMUserExpression : public UserExpression {
   };
 
   LLVMUserExpression(ExecutionContextScope &exe_scope, llvm::StringRef expr,
-                     llvm::StringRef prefix, lldb::LanguageType language,
+                     llvm::StringRef prefix, SourceLanguage language,
                      ResultType desired_type,
                      const EvaluateExpressionOptions &options);
   ~LLVMUserExpression() override;

lldb/include/lldb/Expression/UserExpression.h

@@ -56,7 +56,7 @@ class UserExpression : public Expression {
   ///     If not eResultTypeAny, the type to use for the expression
   ///     result.
   UserExpression(ExecutionContextScope &exe_scope, llvm::StringRef expr,
-                 llvm::StringRef prefix, lldb::LanguageType language,
+                 llvm::StringRef prefix, SourceLanguage language,
                  ResultType desired_type,
                  const EvaluateExpressionOptions &options);
 
@@ -202,7 +202,7 @@ class UserExpression : public Expression {
   virtual bool IsParseCacheable() { return true; }
   /// Return the language that should be used when parsing.  To use the
   /// default, return eLanguageTypeUnknown.
-  lldb::LanguageType Language() const override { return m_language; }
+  SourceLanguage Language() const override { return m_language; }
 
   /// Return the desired result type of the function, or eResultTypeAny if
   /// indifferent.
@@ -315,19 +315,22 @@ class UserExpression : public Expression {
                            lldb::ProcessSP &process_sp,
                            lldb::StackFrameSP &frame_sp);
 
-  Address m_address;       ///< The address the process is stopped in.
-  std::string m_expr_text; ///< The text of the expression, as typed by the user
-  std::string m_expr_prefix; ///< The text of the translation-level definitions,
-                             ///as provided by the user
-  std::string m_fixed_text; ///< The text of the expression with fix-its applied
-                            ///- this won't be set if the fixed text doesn't
-                            ///parse.
-  lldb::LanguageType m_language; ///< The language to use when parsing
-                                 ///(eLanguageTypeUnknown means use defaults)
-  ResultType m_desired_type; ///< The type to coerce the expression's result to.
-                             ///If eResultTypeAny, inferred from the expression.
-  EvaluateExpressionOptions
-      m_options; ///< Additional options provided by the user.
+  /// The address the process is stopped in.
+  Address m_address;
+  /// The text of the expression, as typed by the user.
+  std::string m_expr_text;
+  /// The text of the translation-level definitions, as provided by the user.
+  std::string m_expr_prefix;
+  /// The text of the expression with fix-its applied this won't be set if the
+  /// fixed text doesn't parse.
+  std::string m_fixed_text;
+  /// The language to use when parsing (unknown means use defaults).
+  SourceLanguage m_language;
+  /// The type to coerce the expression's result to. If eResultTypeAny, inferred
+  /// from the expression.
+  ResultType m_desired_type;
+  /// Additional options provided by the user.
+  EvaluateExpressionOptions m_options;
 };
 
 } // namespace lldb_private

lldb/include/lldb/Symbol/TypeSystem.h

@@ -483,12 +483,10 @@ class TypeSystem : public PluginInterface,
     return IsPointerOrReferenceType(type, nullptr);
   }
 
-  virtual UserExpression *
-  GetUserExpression(llvm::StringRef expr, llvm::StringRef prefix,
-                    lldb::LanguageType language,
-                    Expression::ResultType desired_type,
-                    const EvaluateExpressionOptions &options,
-                    ValueObject *ctx_obj) {
+  virtual UserExpression *GetUserExpression(
+      llvm::StringRef expr, llvm::StringRef prefix, SourceLanguage language,
+      Expression::ResultType desired_type,
+      const EvaluateExpressionOptions &options, ValueObject *ctx_obj) {
     return nullptr;
   }
 

lldb/include/lldb/Target/StackFrame.h

@@ -446,13 +446,12 @@ class StackFrame : public ExecutionContextScope,
   /// Query this frame to determine what the default language should be when
   /// parsing expressions given the execution context.
   ///
-  /// \return
-  ///   The language of the frame if known, else lldb::eLanguageTypeUnknown.
-  lldb::LanguageType GetLanguage();
+  /// \return   The language of the frame if known.
+  SourceLanguage GetLanguage();
 
-  // similar to GetLanguage(), but is allowed to take a potentially incorrect
-  // guess if exact information is not available
-  lldb::LanguageType GuessLanguage();
+  /// Similar to GetLanguage(), but is allowed to take a potentially incorrect
+  /// guess if exact information is not available
+  SourceLanguage GuessLanguage();
 
   /// Attempt to econstruct the ValueObject for a given raw address touched by
   /// the current instruction.  The ExpressionPath should indicate how to get

lldb/include/lldb/Target/Target.h

@@ -200,7 +200,7 @@ class TargetProperties : public Properties {
 
   bool GetBreakpointsConsultPlatformAvoidList();
 
-  lldb::LanguageType GetLanguage() const;
+  SourceLanguage GetLanguage() const;
 
   llvm::StringRef GetExpressionPrefixContents();
 
@@ -310,9 +310,18 @@ class EvaluateExpressionOptions {
     m_execution_policy = policy;
   }
 
-  lldb::LanguageType GetLanguage() const { return m_language; }
+  SourceLanguage GetLanguage() const { return m_language; }
 
-  void SetLanguage(lldb::LanguageType language) { m_language = language; }
+  void SetLanguage(lldb::LanguageType language_type) {
+    m_language = SourceLanguage(language_type);
+  }
+
+  /// Set the language using a pair of language code and version as
+  /// defined by the DWARF 6 specification.
+  /// WARNING: These codes may change until DWARF 6 is finalized.
+  void SetLanguage(uint16_t name, uint32_t version) {
+    m_language = SourceLanguage(name, version);
+  }
 
   bool DoesCoerceToId() const { return m_coerce_to_id; }
 
@@ -445,7 +454,7 @@ class EvaluateExpressionOptions {
 
 private:
   ExecutionPolicy m_execution_policy = default_execution_policy;
-  lldb::LanguageType m_language = lldb::eLanguageTypeUnknown;
+  SourceLanguage m_language;
   std::string m_prefix;
   bool m_coerce_to_id = false;
   bool m_unwind_on_error = true;
@@ -1160,7 +1169,7 @@ class Target : public std::enable_shared_from_this<Target>,
 
   UserExpression *
   GetUserExpressionForLanguage(llvm::StringRef expr, llvm::StringRef prefix,
-                               lldb::LanguageType language,
+                               SourceLanguage language,
                                Expression::ResultType desired_type,
                                const EvaluateExpressionOptions &options,
                                ValueObject *ctx_obj, Status &error);

lldb/include/lldb/lldb-private-types.h

@@ -96,6 +96,25 @@ struct RegisterSet {
   const uint32_t *registers;
 };
 
+/// A type-erased pair of llvm::dwarf::SourceLanguageName and version.
+struct SourceLanguage {
+  SourceLanguage() = default;
+  SourceLanguage(lldb::LanguageType language_type);
+  SourceLanguage(uint16_t name, uint32_t version)
+      : name(name), version(version) {}
+  SourceLanguage(std::optional<std::pair<uint32_t, uint16_t>> name_vers)
+      : name(name_vers ? name_vers->first : 0),
+        version(name_vers ? name_vers->second : 0) {}
+  operator bool() const { return name > 0; }
+  lldb::LanguageType AsLanguageType() const;
+  llvm::StringRef GetDescription() const;
+  bool IsC() const;
+  bool IsObjC() const;
+  bool IsCPlusPlus() const;
+  uint16_t name = 0;
+  uint32_t version = 0;
+};
+
 struct OptionEnumValueElement {
   int64_t value;
   const char *string_value;

lldb/packages/Python/lldbsuite/test/configuration.py

@@ -119,6 +119,7 @@
 
 # LLDB library directory.
 lldb_libs_dir = None
+lldb_built_include_dir = None
 
 libcxx_include_dir = None
 libcxx_include_target_dir = None

lldb/packages/Python/lldbsuite/test/dotest.py

@@ -423,6 +423,7 @@ def parseOptionsAndInitTestdirs():
         configuration.lldb_module_cache_dir = os.path.join(
             configuration.test_build_dir, "module-cache-lldb"
         )
+
     if args.clang_module_cache_dir:
         configuration.clang_module_cache_dir = args.clang_module_cache_dir
     else:
@@ -432,6 +433,8 @@ def parseOptionsAndInitTestdirs():
 
     if args.lldb_libs_dir:
         configuration.lldb_libs_dir = args.lldb_libs_dir
+    if args.lldb_built_include_dir:
+        configuration.lldb_built_include_dir = args.lldb_built_include_dir
 
     if args.enabled_plugins:
         configuration.enabled_plugins = args.enabled_plugins

lldb/packages/Python/lldbsuite/test/dotest_args.py

@@ -236,6 +236,12 @@ def create_parser():
         metavar="The clang module cache directory used by Clang",
         help="The clang module cache directory used in the Make files by Clang while building tests. Defaults to <test build directory>/module-cache-clang.",
     )
+    group.add_argument(
+        "--lldb-built-include-dir",
+        dest="lldb_built_include_dir",
+        metavar="path",
+        help="The path to LLDB built includes directory (containing languages.h)",
+    )
     group.add_argument(
         "--lldb-libs-dir",
         dest="lldb_libs_dir",

lldb/packages/Python/lldbsuite/test/lldbtest.py

@@ -1473,23 +1473,25 @@ def buildDriver(self, sources, exe_name):
             d = {
                 "CXX_SOURCES": sources,
                 "EXE": exe_name,
-                "CFLAGS_EXTRAS": "%s %s -I%s"
+                "CFLAGS_EXTRAS": "%s %s -I%s -I%s"
                 % (
                     stdflag,
                     stdlibflag,
                     os.path.join(os.environ["LLDB_SRC"], "include"),
+                    configuration.lldb_built_include_dir,
                 ),
                 "LD_EXTRAS": "-L%s -lliblldb" % lib_dir,
             }
         else:
             d = {
                 "CXX_SOURCES": sources,
                 "EXE": exe_name,
-                "CFLAGS_EXTRAS": "%s %s -I%s"
+                "CFLAGS_EXTRAS": "%s %s -I%s -I%s"
                 % (
                     stdflag,
                     stdlibflag,
                     os.path.join(os.environ["LLDB_SRC"], "include"),
+                    configuration.lldb_built_include_dir,
                 ),
                 "LD_EXTRAS": "-L%s -llldb -Wl,-rpath,%s" % (lib_dir, lib_dir),
             }
@@ -1508,7 +1510,8 @@ def buildLibrary(self, sources, lib_name):
             d = {
                 "DYLIB_CXX_SOURCES": sources,
                 "DYLIB_NAME": lib_name,
-                "CFLAGS_EXTRAS": "%s -stdlib=libc++" % stdflag,
+                "CFLAGS_EXTRAS": "%s -stdlib=libc++ -I%s" %
+                (stdflag, configuration.lldb_built_include_dir),
                 "FRAMEWORK_INCLUDES": "-F%s" % self.framework_dir,
                 "LD_EXTRAS": "%s -Wl,-rpath,%s -dynamiclib"
                 % (self.lib_lldb, self.framework_dir),
@@ -1517,16 +1520,18 @@ def buildLibrary(self, sources, lib_name):
             d = {
                 "DYLIB_CXX_SOURCES": sources,
                 "DYLIB_NAME": lib_name,
-                "CFLAGS_EXTRAS": "%s -I%s "
-                % (stdflag, os.path.join(os.environ["LLDB_SRC"], "include")),
+                "CFLAGS_EXTRAS": "%s -I%s -I%s"
+                % (stdflag, os.path.join(os.environ["LLDB_SRC"], "include"),
+                   configuration.lldb_built_include_dir),
                 "LD_EXTRAS": "-shared -l%s\liblldb.lib" % lib_dir,
             }
         else:
             d = {
                 "DYLIB_CXX_SOURCES": sources,
                 "DYLIB_NAME": lib_name,
-                "CFLAGS_EXTRAS": "%s -I%s -fPIC"
-                % (stdflag, os.path.join(os.environ["LLDB_SRC"], "include")),
+                "CFLAGS_EXTRAS": "%s -I%s -I%s -fPIC"
+                % (stdflag, os.path.join(os.environ["LLDB_SRC"], "include"),
+                   configuration.lldb_built_include_dir),
                 "LD_EXTRAS": "-shared -L%s -llldb -Wl,-rpath,%s" % (lib_dir, lib_dir),
             }
         if self.TraceOn():

lldb/source/API/CMakeLists.txt

@@ -20,6 +20,10 @@ if(LLDB_ENABLE_LUA)
   set(lldb_lua_wrapper ${lua_bindings_dir}/LLDBWrapLua.cpp)
 endif()
 
+lldb_tablegen(../../include/lldb/API/SBLanguages.h -gen-lldb-sbapi-dwarf-enum
+  SOURCE ${LLVM_MAIN_INCLUDE_DIR}/llvm/BinaryFormat/Dwarf.def
+  TARGET lldb-sbapi-dwarf-enums)
+
 add_lldb_library(liblldb SHARED ${option_framework}
   SBAddress.cpp
   SBAttachInfo.cpp
@@ -100,6 +104,9 @@ add_lldb_library(liblldb SHARED ${option_framework}
   ${lldb_python_wrapper}
   ${lldb_lua_wrapper}
 
+  DEPENDS
+    lldb-sbapi-dwarf-enums
+  
   LINK_LIBS
     lldbBreakpoint
     lldbCore

lldb/source/API/SBExpressionOptions.cpp

@@ -156,6 +156,13 @@ void SBExpressionOptions::SetLanguage(lldb::LanguageType language) {
   m_opaque_up->SetLanguage(language);
 }
 
+void SBExpressionOptions::SetLanguage(SBSourceLanguageName name,
+                                      uint32_t version) {
+  LLDB_INSTRUMENT_VA(this, name, version);
+
+  m_opaque_up->SetLanguage(name, version);
+}
+
 void SBExpressionOptions::SetCancelCallback(
     lldb::ExpressionCancelCallback callback, void *baton) {
   LLDB_INSTRUMENT_VA(this, callback, baton);

lldb/source/API/SBFrame.cpp

@@ -1024,10 +1024,10 @@ SBValue SBFrame::EvaluateExpression(const char *expr) {
     options.SetFetchDynamicValue(fetch_dynamic_value);
     options.SetUnwindOnError(true);
     options.SetIgnoreBreakpoints(true);
-    if (target->GetLanguage() != eLanguageTypeUnknown)
-      options.SetLanguage(target->GetLanguage());
-    else
-      options.SetLanguage(frame->GetLanguage());
+    SourceLanguage language = target->GetLanguage();
+    if (!language)
+      language = frame->GetLanguage();
+    options.SetLanguage((SBSourceLanguageName)language.name, language.version);
     return EvaluateExpression(expr, options);
   } else {
     Status error;
@@ -1053,10 +1053,12 @@ SBFrame::EvaluateExpression(const char *expr,
 
   StackFrame *frame = exe_ctx.GetFramePtr();
   Target *target = exe_ctx.GetTargetPtr();
-  if (target && target->GetLanguage() != eLanguageTypeUnknown)
-    options.SetLanguage(target->GetLanguage());
-  else if (frame)
-    options.SetLanguage(frame->GetLanguage());
+  SourceLanguage language;
+  if (target)
+    language = target->GetLanguage();
+  if (!language && frame)
+    language = frame->GetLanguage();
+  options.SetLanguage((SBSourceLanguageName)language.name, language.version);
   return EvaluateExpression(expr, options);
 }
 
@@ -1074,10 +1076,12 @@ SBValue SBFrame::EvaluateExpression(const char *expr,
   options.SetIgnoreBreakpoints(true);
   StackFrame *frame = exe_ctx.GetFramePtr();
   Target *target = exe_ctx.GetTargetPtr();
-  if (target && target->GetLanguage() != eLanguageTypeUnknown)
-    options.SetLanguage(target->GetLanguage());
-  else if (frame)
-    options.SetLanguage(frame->GetLanguage());
+  SourceLanguage language;
+  if (target)
+    language = target->GetLanguage();
+  if (!language && frame)
+    language = frame->GetLanguage();
+  options.SetLanguage((SBSourceLanguageName)language.name, language.version);
   return EvaluateExpression(expr, options);
 }
 
@@ -1218,7 +1222,7 @@ lldb::LanguageType SBFrame::GuessLanguage() const {
     if (stop_locker.TryLock(&process->GetRunLock())) {
       frame = exe_ctx.GetFramePtr();
       if (frame) {
-        return frame->GuessLanguage();
+        return frame->GuessLanguage().AsLanguageType();
       }
     }
   }