Don't update the triple when loading additional dylibs in the expression evaluator

This is a surgical fix for the 5.9 branch to address a design
problem. When a new Swift module is imported in the expression
evaluator, LLDB deserialized the compiler invocation from it and the
way the code was written it replaced the existing compiler invocation
instead of just adding additional search paths. This patch fixes this
by adding a paths-only mode that uses a temporary compiler invocation
object.

rdar://115747362

Author: adrian-prantl

lldb/source/Plugins/TypeSystem/Swift/SwiftASTContext.cpp

@@ -1177,7 +1177,8 @@ static bool DeserializeAllCompilerFlags(swift::CompilerInvocation &invocation,
                                         const std::string &m_description,
                                         llvm::raw_ostream &error,
                                         bool &got_serialized_options,
-                                        bool &found_swift_modules) {
+                                        bool &found_swift_modules,
+                                        bool search_paths_only = false) {
   bool found_validation_errors = false;
   got_serialized_options = false;
 
@@ -1287,7 +1288,7 @@ static bool DeserializeAllCompilerFlags(swift::CompilerInvocation &invocation,
 
       /// Initialize the compiler invocation with it the search paths from a
       /// serialized AST.
-      auto deserializeCompilerFlags = [&]() -> bool {
+      auto deserializeCompilerFlags = [&](swift::CompilerInvocation &invocation) {
         auto result = invocation.loadFromSerializedAST(moduleData);
         if (result != swift::serialization::Status::Valid) {
           error << "Could not deserialize " << info.name << ":\n"
@@ -1410,13 +1411,17 @@ static bool DeserializeAllCompilerFlags(swift::CompilerInvocation &invocation,
         return true;
       };
 
-      got_serialized_options |= deserializeCompilerFlags();
-
-      LOG_PRINTF(
-          GetLog(LLDBLog::Types), "SDK path from module \"%s\" was \"%s\".",
-          info.name.str().c_str(), invocation.getSDKPath().str().c_str());
-      // We will deduce a matching SDK path from DWARF later.
-      invocation.setSDKPath("");
+      if (search_paths_only) {
+        swift::CompilerInvocation fresh_invocation;
+        got_serialized_options |= deserializeCompilerFlags(fresh_invocation);
+      } else {
+        got_serialized_options |= deserializeCompilerFlags(invocation);
+        LOG_PRINTF(
+            GetLog(LLDBLog::Types), "SDK path from module \"%s\" was \"%s\".",
+            info.name.str().c_str(), invocation.getSDKPath().str().c_str());
+        // We will deduce a matching SDK path from DWARF later.
+        invocation.setSDKPath("");
+      }
     }
   }
 
@@ -8374,7 +8379,7 @@ bool SwiftASTContextForExpressions::CacheUserImports(
                       invocation, ast_file, {file_or_err->get()->getBuffer()},
                       path_remap, discover_implicit_search_paths,
                       m_description.str().str(), errs, got_serialized_options,
-                      found_swift_modules)) {
+                      found_swift_modules, /*search_paths_only = */true)) {
                 LOG_PRINTF(GetLog(LLDBLog::Types), "Could not parse %s: %s",
                            ast_file.str().c_str(), error.str().str().c_str());
               }

lldb/test/API/lang/swift/late_expr_dylib/Dylib.swift

@@ -0,0 +1,22 @@
+# This Makefile recursively calls itself, hence the ?=.
+SWIFT_SOURCES ?= main.swift
+SWIFTFLAGS_EXTRAS ?= -target $(TRIPLE) -I$(BUILDDIR)
+all: Dylib $(EXE)
+
+include Makefile.rules
+
+.PHONY: Dylib
+Dylib:
+	$(MAKE) MAKE_DSYM=$(MAKE_DSYM) CC=$(CC) SWIFTC=$(SWIFTC) \
+		ARCH=$(ARCH) DSYMUTIL=$(DSYMUTIL) \
+		VPATH=$(SRCDIR) -I $(SRCDIR) \
+		SWIFT_SOURCES= \
+		SWIFTFLAGS_EXTRAS="-target $(DYLIB_TRIPLE) -I__PATH_FROM_DYLIB__" \
+		-f $(SRCDIR)/Makefile \
+		DYLIB_FILENAME=Dylib.dylib \
+		DYLIB_SWIFT_SOURCES=Dylib.swift \
+		DYLIB_NAME=Dylib \
+		DYLIB_ONLY=YES \
+		LD_EXTRAS="-lSwiftCore" \
+		Dylib.dylib
+

lldb/test/API/lang/swift/late_expr_dylib/Makefile

@@ -0,0 +1,29 @@
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.decorators import *
+import lldbsuite.test.lldbutil as lldbutil
+
+
+class TestSwiftLateDylib(TestBase):
+    mydir = TestBase.compute_mydir(__file__)
+
+    @skipUnlessDarwin
+    @swiftTest
+    @skipIfDarwinEmbedded
+    def test(self):
+        """Test that a late loaded Swift dylib is debuggable"""
+        arch = self.getArchitecture()
+        self.build(dictionary={"TRIPLE": arch + "-apple-macosx11.0.0", "ARCH": arch,
+                               "DYLIB_TRIPLE": arch + "-apple-macosx12.0.0"})
+        log = self.getBuildArtifact("types.log")
+        self.runCmd('log enable lldb types -f "%s"' % log)
+        lldbutil.run_to_source_breakpoint(self, "break here",
+                                          lldb.SBFileSpec("main.swift"))
+        self.expect("expr -- import Dylib")
+        # Scan through the types log.
+        self.filecheck('platform shell cat "%s"' % log, __file__)
+# CHECK: SwiftASTContextForExpressions::LogConfiguration(){{.*}}Architecture{{.*}}-apple-macosx11.0.0
+# CHECK-NOT: __PATH_FROM_DYLIB__
+#       Verify that the deployment target didn't change:
+# CHECK: SwiftASTContextForExpressions::LogConfiguration(){{.*}}Architecture{{.*}}-apple-macosx11.0.0
+#       But LLDB has picked up extra paths:
+# CHECK: SwiftASTContextForExpressions::LogConfiguration(){{.*}}__PATH_FROM_DYLIB__

lldb/test/API/lang/swift/late_expr_dylib/TestSwiftLateExprDylib.py

@@ -0,0 +1 @@
+print("break here")