[clang] [lld] [llvm] [llvm][lld][clang] Delay initializing TargetOptions in LTO builds until a Triple is available (PR #179509)

[Teresa Johnson via cfe-commits]

================
@@ -46,47 +46,52 @@ static std::string getThinLTOOutputFile(Ctx &ctx, StringRef modulePath) {
 static lto::Config createConfig(Ctx &ctx) {
   lto::Config c;
 
-  // LLD supports the new relocations and address-significance tables.
-  c.Options = initTargetOptionsFromCodeGenFlags();
-  c.Options.EmitAddrsig = true;
-  for (StringRef C : ctx.arg.mllvmOpts)
-    c.MllvmArgs.emplace_back(C.str());
-
-  // Always emit a section per function/datum with LTO.
-  c.Options.FunctionSections = true;
-  c.Options.DataSections = true;
-
-  // Check if basic block sections must be used.
-  // Allowed values for --lto-basic-block-sections are "all",
-  // "<file name specifying basic block ids>", or none.  This is the equivalent
-  // of -fbasic-block-sections= flag in clang.
-  if (!ctx.arg.ltoBasicBlockSections.empty()) {
-    if (ctx.arg.ltoBasicBlockSections == "all") {
-      c.Options.BBSections = BasicBlockSection::All;
-    } else if (ctx.arg.ltoBasicBlockSections == "labels") {
-      c.Options.BBAddrMap = true;
-      Warn(ctx)
-          << "'--lto-basic-block-sections=labels' is deprecated; Please use "
-             "'--lto-basic-block-address-map' instead";
-    } else if (ctx.arg.ltoBasicBlockSections == "none") {
-      c.Options.BBSections = BasicBlockSection::None;
-    } else {
-      ErrorOr<std::unique_ptr<MemoryBuffer>> MBOrErr =
-          MemoryBuffer::getFile(ctx.arg.ltoBasicBlockSections.str());
-      if (!MBOrErr) {
-        ErrAlways(ctx) << "cannot open " << ctx.arg.ltoBasicBlockSections << ":"
-                       << MBOrErr.getError().message();
+  // Set up the callback to modify TargetOptions.
+  c.ModifyTargetOptions = [&](TargetOptions &Options) -> void {
+    // LLD supports the new relocations and address-significance tables.
+    Options.EmitAddrsig = true;
+    // Always emit a section per function/datum with LTO.
+    Options.FunctionSections = true;
+    Options.DataSections = true;
+
+    // Check if basic block sections must be used.
+    // Allowed values for --lto-basic-block-sections are "all",
+    // "<file name specifying basic block ids>", or none.  This is the
+    // equivalent of -fbasic-block-sections= flag in clang.
+    if (!ctx.arg.ltoBasicBlockSections.empty()) {
+      if (ctx.arg.ltoBasicBlockSections == "all") {
+        Options.BBSections = BasicBlockSection::All;
+      } else if (ctx.arg.ltoBasicBlockSections == "labels") {
+        Options.BBAddrMap = true;
+        Warn(ctx)
+            << "'--lto-basic-block-sections=labels' is deprecated; Please use "
+               "'--lto-basic-block-address-map' instead";
+      } else if (ctx.arg.ltoBasicBlockSections == "none") {
+        Options.BBSections = BasicBlockSection::None;
       } else {
-        c.Options.BBSectionsFuncListBuf = std::move(*MBOrErr);
+        ErrorOr<std::unique_ptr<MemoryBuffer>> MBOrErr =
+            MemoryBuffer::getFile(ctx.arg.ltoBasicBlockSections.str());
----------------
teresajohnson wrote:

I threw your full comment above including what you did and the errors into Gemini and it says the issue is that when you do that lambda capture it becomes const because the lambda operator() is by default const (and you can't move out of a const). To fix it says make the lambda mutable.

https://github.com/llvm/llvm-project/pull/179509