[C++20] [Modules] Remove unmaintained Header Module

Currently there is a -emit-header-module mode, which can combine several
headers together as a module interface. However, this breaks our
assumption (for standard c++ modules) about module interface. The module
interface should come from a module interface unit. And if it is a
header, it should be a header unit. And currently we have no ideas to
combine several headers together.

So I think this mode is an experimental one and it is not maintained and
it is not used. So it will be better to remove them.

Reviewed By: Bigcheese, dblaikie, bruno

Differential Revision: https://reviews.llvm.org/D137609

1 files changed, 0 insertions, 23 deletions

diff --git a/clang/lib/Lex/ModuleMap.cpp b/clang/lib/Lex/ModuleMap.cpp
index 210fab7..9ff0204 100644
--- a/clang/lib/Lex/ModuleMap.cpp
+++ b/clang/lib/Lex/ModuleMap.cpp
@@ -899,29 +899,6 @@ Module *ModuleMap::createModuleForInterfaceUnit(SourceLocation Loc,
   return Result;
 }
 
-Module *ModuleMap::createHeaderModule(StringRef Name,
-                                      ArrayRef<Module::Header> Headers) {
-  assert(LangOpts.CurrentModule == Name && "module name mismatch");
-  assert(!Modules[Name] && "redefining existing module");
-
-  auto *Result =
-      new Module(Name, SourceLocation(), nullptr, /*IsFramework*/ false,
-                 /*IsExplicit*/ false, NumCreatedModules++);
-  Result->Kind = Module::ModuleInterfaceUnit;
-  Modules[Name] = SourceModule = Result;
-
-  for (const Module::Header &H : Headers) {
-    auto *M = new Module(H.NameAsWritten, SourceLocation(), Result,
-                         /*IsFramework*/ false,
-                         /*IsExplicit*/ true, NumCreatedModules++);
-    // Header modules are implicitly 'export *'.
-    M->Exports.push_back(Module::ExportDecl(nullptr, true));
-    addHeader(M, H, NormalHeader);
-  }
-
-  return Result;
-}
-
 Module *ModuleMap::createHeaderUnit(SourceLocation Loc, StringRef Name,
                                     Module::Header H) {
   assert(LangOpts.CurrentModule == Name && "module name mismatch");