[clang][deps] Fix __has_include behavior with umbrella headers (#70144)

Previously, Clang wouldn't try to resolve the module for the header
being checked via `__has_include`. This meant that such header was
considered textual (a.k.a. part of the module Clang is currently
compiling).

rdar://116926060

clang/lib/Lex/PPMacroExpansion.cpp

@@ -1248,10 +1248,15 @@ static bool EvaluateHasIncludeCommon(Token &Tok, IdentifierInfo *II,
   if (Filename.empty())
     return false;
 
+  // Passing this to LookupFile forces header search to check whether the found
+  // file belongs to a module. Skipping that check could incorrectly mark
+  // modular header as textual, causing issues down the line.
+  ModuleMap::KnownHeader KH;
+
   // Search include directories.
   OptionalFileEntryRef File =
       PP.LookupFile(FilenameLoc, Filename, isAngled, LookupFrom, LookupFromFile,
-                    nullptr, nullptr, nullptr, nullptr, nullptr, nullptr);
+                    nullptr, nullptr, nullptr, &KH, nullptr, nullptr);
 
   if (PPCallbacks *Callbacks = PP.getPPCallbacks()) {
     SrcMgr::CharacteristicKind FileType = SrcMgr::C_User;

clang/test/ClangScanDeps/modules-has-include-umbrella-header.c

@@ -0,0 +1,76 @@
+// This test checks that __has_include(<FW/PrivateHeader.h>) in a module does
+// not clobber #include <FW/PrivateHeader.h> in importers of said module.
+
+// RUN: rm -rf %t
+// RUN: split-file %s %t
+
+//--- cdb.json.template
+[{
+  "file": "DIR/tu.c",
+  "directory": "DIR",
+  "command": "clang DIR/tu.c -fmodules -fmodules-cache-path=DIR/cache -I DIR/modules -F DIR/frameworks -o DIR/tu.o"
+}]
+
+//--- frameworks/FW.framework/Modules/module.private.modulemap
+framework module FW_Private {
+  umbrella header "A.h"
+  module * { export * }
+}
+//--- frameworks/FW.framework/PrivateHeaders/A.h
+#include <FW/B.h>
+//--- frameworks/FW.framework/PrivateHeaders/B.h
+#include "dependency.h"
+
+//--- modules/module.modulemap
+module Poison { header "poison.h" }
+module Import { header "import.h" }
+module Dependency { header "dependency.h" }
+//--- modules/poison.h
+#if __has_include(<FW/B.h>)
+#define HAS_B 1
+#else
+#define HAS_B 0
+#endif
+//--- modules/import.h
+#include <FW/B.h>
+//--- modules/dependency.h
+
+//--- tu.c
+#include "poison.h"
+
+#if __has_include(<FW/B.h>)
+#endif
+
+#include "import.h"
+
+#include <FW/B.h>
+
+// RUN: sed -e "s|DIR|%/t|g" %t/cdb.json.template > %t/cdb.json
+// RUN: clang-scan-deps -compilation-database %t/cdb.json -format experimental-full > %t/deps.json
+// RUN: cat %t/deps.json | sed 's:\\\\\?:/:g' | FileCheck %s -DPREFIX=%/t
+
+// Let's check that the TU actually depends on `FW_Private` (and does not treat FW/B.h as textual).
+// CHECK:      {
+// CHECK:        "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": "FW_Private"
+// CHECK-NEXT:             }
+// CHECK:                ],
+// CHECK-NEXT:           "command-line": [
+// CHECK:                ],
+// CHECK-NEXT:           "executable": "clang",
+// CHECK-NEXT:           "file-deps": [
+// CHECK-NEXT:             "[[PREFIX]]/tu.c"
+// CHECK-NEXT:           ],
+// CHECK-NEXT:           "input-file": "[[PREFIX]]/tu.c"
+// CHECK-NEXT:         }
+// CHECK:            ]
+// CHECK:          }
+// CHECK:        ]
+// CHECK:      }