[Modules] textual headers in submodules never resolve their uses

[ian-twilightcoder]

When an include from a textual header is resolved, the textual header's submodule is used as the requesting module. The submodule's uses are resolved, but that doesn't work because only top level modules have uses, and only the top level module uses are used for checking uses in Module::directlyUses. ModuleMap::resolveUses to resolve the top level module instead of the submodule.

[ian-twilightcoder]

Somewhat indirectly caused by https://reviews.llvm.org/D132779

[llvmbot]

@llvm/pr-subscribers-clang

@llvm/pr-subscribers-clang-modules

Author: Ian Anderson (ian-twilightcoder)

Changes

When an include from a textual header is resolved, the textual header's submodule is used as the requesting module. The submodule's uses are resolved, but that doesn't work because only top level modules have uses, and only the top level module uses are used for checking uses in Module::directlyUses. ModuleMap::resolveUses to resolve the top level module instead of the submodule.

---

Full diff: https://github.com/llvm/llvm-project/pull/69651.diff

5 Files Affected:

• (modified) clang/lib/Lex/ModuleMap.cpp (+7-6)
• (added) clang/test/Modules/Inputs/no-undeclared-includes/assert.h (+1)
• (added) clang/test/Modules/Inputs/no-undeclared-includes/base.h (+6)
• (added) clang/test/Modules/Inputs/no-undeclared-includes/module.modulemap (+11)
• (added) clang/test/Modules/no-undeclared-includes.c (+5)

diff --git a/clang/lib/Lex/ModuleMap.cpp b/clang/lib/Lex/ModuleMap.cpp
index f65a5f145c04395..259c97796ae19f2 100644
--- a/clang/lib/Lex/ModuleMap.cpp
+++ b/clang/lib/Lex/ModuleMap.cpp
@@ -1398,16 +1398,17 @@ bool ModuleMap::resolveExports(Module *Mod, bool Complain) {
 }
 
 bool ModuleMap::resolveUses(Module *Mod, bool Complain) {
-  auto Unresolved = std::move(Mod->UnresolvedDirectUses);
-  Mod->UnresolvedDirectUses.clear();
+  auto *Top = Mod->getTopLevelModule();
+  auto Unresolved = std::move(Top->UnresolvedDirectUses);
+  Top->UnresolvedDirectUses.clear();
   for (auto &UDU : Unresolved) {
-    Module *DirectUse = resolveModuleId(UDU, Mod, Complain);
+    Module *DirectUse = resolveModuleId(UDU, Top, Complain);
     if (DirectUse)
-      Mod->DirectUses.push_back(DirectUse);
+      Top->DirectUses.push_back(DirectUse);
     else
-      Mod->UnresolvedDirectUses.push_back(UDU);
+      Top->UnresolvedDirectUses.push_back(UDU);
   }
-  return !Mod->UnresolvedDirectUses.empty();
+  return !Top->UnresolvedDirectUses.empty();
 }
 
 bool ModuleMap::resolveConflicts(Module *Mod, bool Complain) {
diff --git a/clang/test/Modules/Inputs/no-undeclared-includes/assert.h b/clang/test/Modules/Inputs/no-undeclared-includes/assert.h
new file mode 100644
index 000000000000000..6ca1ffb2ad7ea6e
--- /dev/null
+++ b/clang/test/Modules/Inputs/no-undeclared-includes/assert.h
@@ -0,0 +1 @@
+#include <base.h>
diff --git a/clang/test/Modules/Inputs/no-undeclared-includes/base.h b/clang/test/Modules/Inputs/no-undeclared-includes/base.h
new file mode 100644
index 000000000000000..e559063bef43311
--- /dev/null
+++ b/clang/test/Modules/Inputs/no-undeclared-includes/base.h
@@ -0,0 +1,6 @@
+#ifndef base_h
+#define base_h
+
+
+
+#endif /* base_h */
diff --git a/clang/test/Modules/Inputs/no-undeclared-includes/module.modulemap b/clang/test/Modules/Inputs/no-undeclared-includes/module.modulemap
new file mode 100644
index 000000000000000..23d04305b3becbd
--- /dev/null
+++ b/clang/test/Modules/Inputs/no-undeclared-includes/module.modulemap
@@ -0,0 +1,11 @@
+module cstd [system] [no_undeclared_includes] {
+  use base
+  module assert {
+    textual header "assert.h"
+  }
+}
+
+module base [system] {
+  header "base.h"
+  export *
+}
diff --git a/clang/test/Modules/no-undeclared-includes.c b/clang/test/Modules/no-undeclared-includes.c
new file mode 100644
index 000000000000000..613418ef0041328
--- /dev/null
+++ b/clang/test/Modules/no-undeclared-includes.c
@@ -0,0 +1,5 @@
+// RUN: rm -rf %t
+// RUN: %clang_cc1 -fmodules-cache-path=%t -fmodules -fimplicit-module-maps -I %S/Inputs/no-undeclared-includes %s -verify
+
+// expected-no-diagnostics
+#include <assert.h>

[Bigcheese]

LGTM. The rest of clang reasons about this at the top level module, so so should this.