4 files changed, 52 insertions, 1 deletions
diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
index 1d27f74..0410032 100644
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -1251,6 +1251,33 @@ void Sema::ActOnEndOfTranslationUnit() {
     emitAndClearUnusedLocalTypedefWarnings();
   }
 
+  // C++ standard modules. Diagnose cases where a function is declared inline
+  // in the module purview but has no definition before the end of the TU or
+  // the start of a Private Module Fragment (if one is present).
+  if (!PendingInlineFuncDecls.empty()) {
+    for (auto *D : PendingInlineFuncDecls) {
+      if (auto *FD = dyn_cast<FunctionDecl>(D)) {
+        bool DefInPMF = false;
+        if (auto *FDD = FD->getDefinition()) {
+          assert(FDD->getOwningModule() &&
+                 FDD->getOwningModule()->isModulePurview());
+          DefInPMF = FDD->getOwningModule()->isPrivateModule();
+          if (!DefInPMF)
+            continue;
+        }
+        Diag(FD->getLocation(), diag::err_export_inline_not_defined)
+            << DefInPMF;
+        // If we have a PMF it should be at the end of the ModuleScopes.
+        if (DefInPMF &&
+            ModuleScopes.back().Module->Kind == Module::PrivateModuleFragment) {
+          Diag(ModuleScopes.back().BeginLoc,
+               diag::note_private_module_fragment);
+        }
+      }
+    }
+    PendingInlineFuncDecls.clear();
+  }
+
   // C99 6.9.2p2:
   //   A declaration of an identifier for an object that has file
   //   scope without an initializer, and without a storage-class
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 33b4948..004c1ff 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -9838,6 +9838,19 @@ Sema::ActOnFunctionDeclarator(Scope *S, Declarator &D, DeclContext *DC,
       NewFD->setType(Context.getFunctionType(
           FPT->getReturnType(), FPT->getParamTypes(),
           FPT->getExtProtoInfo().withExceptionSpec(EST_BasicNoexcept)));
+
+    // C++20 [dcl.inline]/7
+    // If an inline function or variable that is attached to a named module
+    // is declared in a definition domain, it shall be defined in that
+    // domain.
+    // So, if the current declaration does not have a definition, we must
+    // check at the end of the TU (or when the PMF starts) to see that we
+    // have a definition at that point.
+    if (isInline && !D.isFunctionDefinition() && getLangOpts().CPlusPlus20 &&
+        NewFD->hasOwningModule() &&
+        NewFD->getOwningModule()->isModulePurview()) {
+      PendingInlineFuncDecls.insert(NewFD);
+    }
   }
 
   // Filter out previous declarations that don't match the scope.
diff --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
index 1d8df94..22d72c3 100644
--- a/clang/lib/Sema/SemaLookup.cpp
+++ b/clang/lib/Sema/SemaLookup.cpp
@@ -5691,7 +5691,7 @@ void Sema::diagnoseMissingImport(SourceLocation UseLoc, NamedDecl *Decl,
   llvm::SmallVector<Module*, 8> UniqueModules;
   llvm::SmallDenseSet<Module*, 8> UniqueModuleSet;
   for (auto *M : Modules) {
-    if (M->Kind == Module::GlobalModuleFragment)
+    if (M->isGlobalModule() || M->isPrivateModule())
       continue;
     if (UniqueModuleSet.insert(M).second)
       UniqueModules.push_back(M);
diff --git a/clang/lib/Sema/SemaModule.cpp b/clang/lib/Sema/SemaModule.cpp
index 757c611..b205fd9 100644
--- a/clang/lib/Sema/SemaModule.cpp
+++ b/clang/lib/Sema/SemaModule.cpp
@@ -910,6 +910,17 @@ Decl *Sema::ActOnFinishExportDecl(Scope *S, Decl *D, SourceLocation RBraceLoc) {
         diagExportedUnnamedDecl(*this, UnnamedDeclKind::Context, Child,
                                 BlockStart);
       }
+      if (auto *FD = dyn_cast<FunctionDecl>(Child)) {
+        // [dcl.inline]/7
+        // If an inline function or variable that is attached to a named module
+        // is declared in a definition domain, it shall be defined in that
+        // domain.
+        // So, if the current declaration does not have a definition, we must
+        // check at the end of the TU (or when the PMF starts) to see that we
+        // have a definition at that point.
+        if (FD->isInlineSpecified() && !FD->isDefined())
+          PendingInlineFuncDecls.insert(FD);
+      }
     }
   }