From 7315d2d721508cc684371dc5495fb6007076b479 Mon Sep 17 00:00:00 2001
From: Bruno Cardoso Lopes <bruno.cardoso@gmail.com>
Date: Thu, 19 Jul 2018 12:32:06 +0000
Subject: [PATCH] [PCH+Modules] Load -fmodule-map-file content before including
 PCHs

Consider:
1) Generate PCH with -fmodules and -fmodule-map-file
2) Use PCH with -fmodules and the same -fmodule-map-file

If we don't load -fmodule-map-file content before including PCHs,
the modules that are dependencies in PCHs cannot get loaded,
since there's no matching module map file when reading back the AST.

rdar://problem/40852867

Differential Revision: https://reviews.llvm.org/D48685

llvm-svn: 337447
---
 clang/lib/Frontend/FrontendAction.cpp              | 32 +++++++++++-----------
 .../module-imported-by-pch-with-modulemap.m        | 16 +++++++++++
 2 files changed, 32 insertions(+), 16 deletions(-)
 create mode 100644 clang/test/Modules/module-imported-by-pch-with-modulemap.m

diff --git a/clang/lib/Frontend/FrontendAction.cpp b/clang/lib/Frontend/FrontendAction.cpp
index 7711d84..a592942 100644
--- a/clang/lib/Frontend/FrontendAction.cpp
+++ b/clang/lib/Frontend/FrontendAction.cpp
@@ -766,6 +766,22 @@ bool FrontendAction::BeginSourceFile(CompilerInstance &CI,
   if (!BeginSourceFileAction(CI))
     goto failure;
 
+  // If we were asked to load any module map files, do so now.
+  for (const auto &Filename : CI.getFrontendOpts().ModuleMapFiles) {
+    if (auto *File = CI.getFileManager().getFile(Filename))
+      CI.getPreprocessor().getHeaderSearchInfo().loadModuleMapFile(
+          File, /*IsSystem*/false);
+    else
+      CI.getDiagnostics().Report(diag::err_module_map_not_found) << Filename;
+  }
+
+  // Add a module declaration scope so that modules from -fmodule-map-file
+  // arguments may shadow modules found implicitly in search paths.
+  CI.getPreprocessor()
+      .getHeaderSearchInfo()
+      .getModuleMap()
+      .finishModuleDeclarationScope();
+
   // Create the AST context and consumer unless this is a preprocessor only
   // action.
   if (!usesPreprocessorOnly()) {
@@ -855,22 +871,6 @@ bool FrontendAction::BeginSourceFile(CompilerInstance &CI,
            "doesn't support modules");
   }
 
-  // If we were asked to load any module map files, do so now.
-  for (const auto &Filename : CI.getFrontendOpts().ModuleMapFiles) {
-    if (auto *File = CI.getFileManager().getFile(Filename))
-      CI.getPreprocessor().getHeaderSearchInfo().loadModuleMapFile(
-          File, /*IsSystem*/false);
-    else
-      CI.getDiagnostics().Report(diag::err_module_map_not_found) << Filename;
-  }
-
-  // Add a module declaration scope so that modules from -fmodule-map-file
-  // arguments may shadow modules found implicitly in search paths.
-  CI.getPreprocessor()
-      .getHeaderSearchInfo()
-      .getModuleMap()
-      .finishModuleDeclarationScope();
-
   // If we were asked to load any module files, do so now.
   for (const auto &ModuleFile : CI.getFrontendOpts().ModuleFiles)
     if (!CI.loadModuleFile(ModuleFile))
diff --git a/clang/test/Modules/module-imported-by-pch-with-modulemap.m b/clang/test/Modules/module-imported-by-pch-with-modulemap.m
new file mode 100644
index 0000000..49303411
--- /dev/null
+++ b/clang/test/Modules/module-imported-by-pch-with-modulemap.m
@@ -0,0 +1,16 @@
+// RUN: rm -rf %t.dst %t.cache
+// RUN: mkdir -p %t.dst/folder-with-modulemap %t.dst/pch-folder
+// RUN: echo '#import "folder-with-modulemap/included.h"' > %t.dst/header.h
+// RUN: echo 'extern int MyModuleVersion;' > %t.dst/folder-with-modulemap/MyModule.h
+// RUN: echo '@import MyModule;' > %t.dst/folder-with-modulemap/included.h
+// RUN: echo 'module MyModule { header "MyModule.h" }' > %t.dst/folder-with-modulemap/MyModule.modulemap
+
+// RUN: %clang_cc1 -emit-pch -o %t.dst/pch-folder/header.pch -fmodule-map-file=%t.dst/folder-with-modulemap/MyModule.modulemap -x objective-c-header -fmodules-cache-path=%t.cache -fmodules -fimplicit-module-maps %t.dst/header.h
+// RUN: %clang_cc1 -fsyntax-only -fmodule-map-file=%t.dst/folder-with-modulemap/MyModule.modulemap -fmodules-cache-path=%t.cache -fmodules -fimplicit-module-maps %s -include-pch %t.dst/pch-folder/header.pch -verify
+
+// expected-no-diagnostics
+
+void test() {
+  (void)MyModuleVersion; // should be found by implicit import
+}
+
-- 
2.7.4