[clang][modules][deps] Parent module maps are affecting

[jansvoboda11]

Summary

Currently, the algorithm for gathering affecting module maps includes only those defining modules that include some headers. This is not entirely correct, though. Some module maps might be "importing" module maps for extern submodules. Such parent module maps are affecting - they do change semantics of the compilation. This patch adds parent module maps into the set of affecting module maps.

Depends on D137197.

[Bigcheese]

lgtm.

clang/lib/Serialization/ASTWriter.cpp

for (const auto &KH : HS.findAllModulesForHeader(File)) {
       if (!KH.getModule())
         continue;
       ModulesToProcess.push_back(KH.getModule());
     }
   }
 
   const ModuleMap &MM = HS.getModuleMap();
 
-  auto ProcessModuleOnce = [&](const Module *Mod) {
+  auto ProcessModuleOnce = [&](const Module *M) {
+    for (const Module *Mod = M; Mod; Mod = Mod->Parent)
       if (ProcessedModules.insert(Mod).second)
         if (auto ModuleMapFile = MM.getModuleMapFileForUniquing(Mod))
           ModuleMaps.insert(*ModuleMapFile);
   };
 
   for (const Module *CurrentModule : ModulesToProcess) {
     ProcessModuleOnce(CurrentModule);
     for (const Module *ImportedModule : CurrentModule->Imports)
       ProcessModuleOnce(ImportedModule);
     for (const Module *UndeclaredModule : CurrentModule->UndeclaredUses)
       ProcessModuleOnce(UndeclaredModule);

clang/test/ClangScanDeps/modules-extern-submodule.c

+// RUN: rm -rf %t
+// RUN: split-file %s %t
+
+//--- tu.m
+@import first;
+
+//--- first/first/module.modulemap
+module first { header "first.h" }
+//--- first/first/first.h
+#include <second/sub.h>
+
+//--- second/second/module.modulemap
+module second { extern module sub "sub.modulemap" }
+//--- second/second/sub.modulemap
+module second.sub { header "sub.h" }
+//--- second/second/sub.h
+@import third;
+
+//--- third/module.modulemap
+module third {}
+
+//--- cdb.json.template
+[{
+  "file": "DIR/tu.c",
+  "directory": "DIR",
+  "command": "clang -I DIR/first -I DIR/second -I DIR/third -fmodules -fmodules-cache-path=DIR/cache -c DIR/tu.m -o DIR/tu.o"
+}]
+
+// RUN: sed "s|DIR|%/t|g" %t/cdb.json.template > %t/cdb.json
+// RUN: clang-scan-deps -compilation-database %t/cdb.json -format experimental-full > %t/result.json
+// RUN: cat %t/result.json | sed 's:\\\\\?:/:g' | FileCheck %s -DPREFIX=%/t
+
+// CHECK:       {
+// CHECK-NEXT:   "modules": [
+// CHECK-NEXT:     {
+// CHECK-NEXT:       "clang-module-deps": [
+// CHECK-NEXT:         {
+// CHECK-NEXT:           "context-hash": "{{.*}}",
+// CHECK-NEXT:           "module-name": "second"
+// CHECK-NEXT:         }
+// CHECK-NEXT:       ],
+// CHECK-NEXT:       "clang-modulemap-file": "[[PREFIX]]/first/first/module.modulemap",
+// CHECK-NEXT:       "command-line": [
+// CHECK-NEXT:         "-cc1",
+// CHECK:              "-fmodule-map-file=[[PREFIX]]/second/second/module.modulemap"
+// CHECK-NOT:          "-fmodule-map-file=[[PREFIX]]/second/second/sub.modulemap"
+// CHECK-NOT:          "-fmodule-map-file=[[PREFIX]]/third/module.modulemap"
+// CHECK:              "-fmodule-file=second=[[PREFIX]]/cache/{{.*}}/second-{{.*}}.pcm"
+// CHECK:            ],
+// CHECK-NEXT:       "context-hash": "{{.*}}",
+// CHECK-NEXT:       "file-deps": [
+// CHECK-NEXT:         "[[PREFIX]]/first/first/first.h",
+// CHECK-NEXT:         "[[PREFIX]]/first/first/module.modulemap",
+// CHECK-NEXT:         "[[PREFIX]]/second/second/module.modulemap",
+// CHECK-NEXT:         "[[PREFIX]]/second/second/sub.modulemap"
+// CHECK-NEXT:       ],
+// CHECK-NEXT:       "name": "first"
+// CHECK-NEXT:     },
+// CHECK-NEXT:     {
+// CHECK-NEXT:       "clang-module-deps": [
+// CHECK-NEXT:         {
+// CHECK-NEXT:           "context-hash": "{{.*}}",
+// CHECK-NEXT:           "module-name": "third"
+// CHECK-NEXT:         }
+// CHECK-NEXT:       ],
+// CHECK-NEXT:       "clang-modulemap-file": "[[PREFIX]]/second/second/module.modulemap",
+// CHECK-NEXT:       "command-line": [
+// CHECK-NEXT:         "-cc1",
+// CHECK:              "-fmodule-map-file=[[PREFIX]]/third/module.modulemap",
+// CHECK:              "-fmodule-file=third=[[PREFIX]]/cache/{{.*}}/third-{{.*}}.pcm",
+// CHECK:            ],
+// CHECK-NEXT:       "context-hash": "{{.*}}",
+// CHECK-NEXT:       "file-deps": [
+// CHECK-NEXT:         "[[PREFIX]]/second/second/module.modulemap",
+// CHECK-NEXT:         "[[PREFIX]]/second/second/sub.h",
+// CHECK-NEXT:         "[[PREFIX]]/second/second/sub.modulemap",
+// CHECK-NEXT:         "[[PREFIX]]/third/module.modulemap"
+// CHECK-NEXT:       ],
+// CHECK-NEXT:       "name": "second"
+// CHECK-NEXT:     },
+// CHECK-NEXT:     {
+// CHECK-NEXT:       "clang-module-deps": [],
+// CHECK-NEXT:       "clang-modulemap-file": "[[PREFIX]]/third/module.modulemap",
+// CHECK-NEXT:       "command-line": [
+// CHECK-NEXT:         "-cc1",
+// CHECK-NOT:          "-fmodule-map-file=
+// CHECK-NOT:          "-fmodule-file=third=
+// CHECK:            ],
+// CHECK-NEXT:       "context-hash": "{{.*}}",
+// CHECK-NEXT:       "file-deps": [
+// CHECK-NEXT:         "[[PREFIX]]/third/module.modulemap"
+// CHECK-NEXT:       ],
+// CHECK-NEXT:       "name": "third"
+// CHECK-NEXT:     }
+// CHECK-NEXT:   ],
+// CHECK-NEXT:   "translation-units": [
+// CHECK-NEXT:     {
+// CHECK-NEXT:       "commands": [
+// CHECK-NEXT:         {
+// CHECK-NEXT:           "clang-context-hash": "{{.*}}",
+// CHECK-NEXT:           "clang-module-deps": [
+// CHECK-NEXT:             {
+// CHECK-NEXT:               "context-hash": "{{.*}}",
+// CHECK-NEXT:               "module-name": "first"
+// CHECK-NEXT:             }
+// CHECK-NEXT:           ],
+// CHECK-NEXT:           "command-line": [
+// CHECK-NEXT:             "-cc1",
+// CHECK:                  "-fmodule-map-file=[[PREFIX]]/first/first/module.modulemap",
+// CHECK:                  "-fmodule-file=first=[[PREFIX]]/cache/{{.*}}/first-{{.*}}.pcm",
+// CHECK:                ],
+// CHECK-NEXT:           "executable": "clang",
+// CHECK-NEXT:           "file-deps": [
+// CHECK-NEXT:             "[[PREFIX]]/tu.m"
+// CHECK-NEXT:           ],
+// CHECK-NEXT:           "input-file": "[[PREFIX]]/tu.c"
+// CHECK-NEXT:         }
+// CHECK-NEXT:       ]
+// CHECK-NEXT:     }
+// CHECK-NEXT:   ]
+// CHECK-NEXT: }
+
+// RUN: %deps-to-rsp %t/result.json --module-name=third > %t/third.cc1.rsp
+// RUN: %deps-to-rsp %t/result.json --module-name=second > %t/second.cc1.rsp
+// RUN: %deps-to-rsp %t/result.json --module-name=first > %t/first.cc1.rsp
+// RUN: %clang @%t/third.cc1.rsp
+// RUN: %clang @%t/second.cc1.rsp
+// RUN: %clang @%t/first.cc1.rsp