[clang][deps] Ensure reported context hash is strict

One of main goals of the dependency scanner is to be strict about module compatibility. This is achieved through strict context hash. This patch ensures that strict context hash is enabled not only during the scan itself (and its minimized implicit build), but also when actually reporting the dependency.

Reviewed By: dexonsmith

Differential Revision: https://reviews.llvm.org/D111720

Author: jansvoboda11

clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp

@@ -56,6 +56,14 @@ CompilerInvocation ModuleDepCollector::makeInvocationForModuleBuildWithoutPaths(
 
   Optimize(CI);
 
+  // The original invocation probably didn't have strict context hash enabled.
+  // We will use the context hash of this invocation to distinguish between
+  // multiple incompatible versions of the same module and will use it when
+  // reporting dependencies to the clients. Let's make sure we're using
+  // **strict** context hash in order to prevent accidental sharing of
+  // incompatible modules (e.g. with differences in search paths).
+  CI.getHeaderSearchOpts().ModulesStrictContextHash = true;
+
   return CI;
 }
 

clang/test/ClangScanDeps/Inputs/modules-context-hash/a/dep.h

@@ -0,0 +1,12 @@
+[
+  {
+    "directory": "DIR",
+    "command": "clang -c DIR/tu.c -fmodules -fmodules-cache-path=DIR/cache -IDIR/a -o DIR/tu_a.o",
+    "file": "DIR/tu.c"
+  },
+  {
+    "directory": "DIR",
+    "command": "clang -c DIR/tu.c -fmodules -fmodules-cache-path=DIR/cache -IDIR/b -o DIR/tu_b.o",
+    "file": "DIR/tu.c"
+  }
+]

clang/test/ClangScanDeps/Inputs/modules-context-hash/b/dep.h

@@ -0,0 +1 @@
+#include "dep.h"

clang/test/ClangScanDeps/Inputs/modules-context-hash/cdb.json.template

@@ -0,0 +1 @@
+module mod { header "mod.h" }

clang/test/ClangScanDeps/Inputs/modules-context-hash/mod.h

@@ -0,0 +1 @@
+#include "mod.h"

clang/test/ClangScanDeps/Inputs/modules-context-hash/module.modulemap

@@ -0,0 +1,89 @@
+// RUN: rm -rf %t && mkdir %t
+// RUN: cp -r %S/Inputs/modules-context-hash/* %t
+
+// Check that the scanner reports the same module as distinct dependencies when
+// a single translation unit gets compiled with multiple command-lines that
+// produce different **strict** context hashes.
+
+// RUN: sed "s|DIR|%/t|g" %S/Inputs/modules-context-hash/cdb.json.template > %t/cdb.json
+// RUN: echo -%t > %t/result.json
+// RUN: clang-scan-deps -compilation-database %t/cdb.json -format experimental-full -j 1 >> %t/result.json
+// RUN: cat %t/result.json | sed 's:\\\\\?:/:g' | FileCheck %s -check-prefix=CHECK
+
+// CHECK:      -[[PREFIX:.*]]
+// CHECK-NEXT: {
+// CHECK-NEXT:   "modules": [
+// CHECK-NEXT:     {
+// CHECK-NEXT:       "clang-module-deps": [],
+// CHECK-NEXT:       "clang-modulemap-file": "[[PREFIX]]/module.modulemap",
+// CHECK-NEXT:       "command-line": [
+// CHECK-NEXT:         "-cc1"
+// CHECK:              "-emit-module"
+// CHECK:              "-I"
+// CHECK:              "[[PREFIX]]/a"
+// CHECK:              "-fmodule-name=mod"
+// CHECK:            ],
+// CHECK-NEXT:       "context-hash": "[[HASH_MOD_A:.*]]",
+// CHECK-NEXT:       "file-deps": [
+// CHECK-NEXT:         "[[PREFIX]]/a/dep.h",
+// CHECK-NEXT:         "[[PREFIX]]/mod.h",
+// CHECK-NEXT:         "[[PREFIX]]/module.modulemap"
+// CHECK-NEXT:       ],
+// CHECK-NEXT:       "name": "mod"
+// CHECK-NEXT:     },
+// CHECK-NEXT:     {
+// CHECK-NEXT:       "clang-module-deps": [],
+// CHECK-NEXT:       "clang-modulemap-file": "[[PREFIX]]/module.modulemap",
+// CHECK-NEXT:       "command-line": [
+// CHECK-NEXT:         "-cc1"
+// CHECK:              "-emit-module"
+// CHECK:              "-I"
+// CHECK:              "[[PREFIX]]/b"
+// CHECK:              "-fmodule-name=mod"
+// CHECK:            ],
+// CHECK-NEXT:       "context-hash": "[[HASH_MOD_B:.*]]",
+// CHECK-NEXT:       "file-deps": [
+// CHECK-NEXT:         "[[PREFIX]]/b/dep.h",
+// CHECK-NEXT:         "[[PREFIX]]/mod.h",
+// CHECK-NEXT:         "[[PREFIX]]/module.modulemap"
+// CHECK-NEXT:       ],
+// CHECK-NEXT:       "name": "mod"
+// CHECK-NEXT:     }
+// CHECK-NEXT:   ],
+// CHECK-NEXT:   "translation-units": [
+// CHECK-NEXT:     {
+// CHECK-NEXT:       "clang-context-hash": "{{.*}}",
+// CHECK-NEXT:       "clang-module-deps": [
+// CHECK-NEXT:         {
+// CHECK-NEXT:           "context-hash": "[[HASH_MOD_A]]",
+// CHECK-NEXT:           "module-name": "mod"
+// CHECK-NEXT:         }
+// CHECK-NEXT:       ],
+// CHECK-NEXT:       "command-line": [
+// CHECK-NEXT:         "-fno-implicit-modules",
+// CHECK-NEXT:         "-fno-implicit-module-maps"
+// CHECK-NEXT:       ],
+// CHECK-NEXT:       "file-deps": [
+// CHECK-NEXT:         "[[PREFIX]]/tu.c"
+// CHECK-NEXT:       ],
+// CHECK-NEXT:       "input-file": "[[PREFIX]]/tu.c"
+// CHECK-NEXT:     },
+// CHECK-NEXT:     {
+// CHECK-NEXT:       "clang-context-hash": "{{.*}}",
+// CHECK-NEXT:       "clang-module-deps": [
+// CHECK-NEXT:         {
+// CHECK-NEXT:           "context-hash": "[[HASH_MOD_B]]",
+// CHECK-NEXT:           "module-name": "mod"
+// CHECK-NEXT:         }
+// CHECK-NEXT:       ],
+// CHECK-NEXT:       "command-line": [
+// CHECK-NEXT:         "-fno-implicit-modules",
+// CHECK-NEXT:         "-fno-implicit-module-maps"
+// CHECK-NEXT:       ],
+// CHECK-NEXT:       "file-deps": [
+// CHECK-NEXT:         "[[PREFIX]]/tu.c"
+// CHECK-NEXT:       ],
+// CHECK-NEXT:       "input-file": "[[PREFIX]]/tu.c"
+// CHECK-NEXT:     }
+// CHECK-NEXT:   ]
+// CHECK-NEXT: }