jansvoboda11 wrote:
We set `RedirectingFileSystem::HasBeenUsed` to `true` while implicitly
compiling one module, but then hand off the same VFS object to implicit compile
of another module. This will cause all modules discovered later to incorrectly
inherit that bit from previous modules. This will also introduce
non-determinism based on the TU that reached a module first (and which modules
it imported on the way). Here's a test case:
```
// This test checks that VFS usage doesn't leak between modules.
// RUN: rm -rf %t && split-file %s %t
// RUN: sed -e "s|DIR|%/t|g" %t/build/cdb.json.in > %t/build/cdb.json
// RUN: sed -e "s|DIR|%/t|g" %t/build/vfs.yaml.in > %t/build/vfs.yaml
// RUN: clang-scan-deps -compilation-database %t/build/cdb.json \
// RUN: -format experimental-full --optimize-args=vfs > %t/deps.json
// RUN: cat %t/deps.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": "B"
// CHECK-NEXT: },
// CHECK-NEXT: {
// CHECK-NEXT: "context-hash": "{{.*}}",
// CHECK-NEXT: "module-name": "C"
// CHECK-NEXT: }
// CHECK-NEXT: ],
// CHECK-NEXT: "clang-modulemap-file":
"[[PREFIX]]/moduleA/module.modulemap",
// CHECK-NEXT: "command-line": [
// Module A needs the VFS overlay because its dependency, module B, needs it.
// CHECK: "-ivfsoverlay"
// CHECK-NEXT: "[[PREFIX]]/build/vfs.yaml"
// CHECK: ],
// CHECK-NEXT: "context-hash": "{{.*}}",
// CHECK-NEXT: "file-deps": [
// CHECK: ],
// CHECK-NEXT: "name": "A"
// CHECK-NEXT: },
// CHECK-NEXT: {
// CHECK-NEXT: "clang-module-deps": [],
// CHECK-NEXT: "clang-modulemap-file":
"[[PREFIX]]/moduleB/module.modulemap",
// CHECK-NEXT: "command-line": [
// Module B needs the VFS overlay because it provides the header referred to by
the module map.
// CHECK: "-ivfsoverlay"
// CHECK-NEXT: "[[PREFIX]]/build/vfs.yaml"
// CHECK: ],
// CHECK-NEXT: "context-hash": "{{.*}}",
// CHECK-NEXT: "file-deps": [
// CHECK: ],
// CHECK-NEXT: "name": "B"
// CHECK-NEXT: },
// CHECK-NEXT: {
// CHECK-NEXT: "clang-module-deps": [],
// CHECK-NEXT: "clang-modulemap-file":
"[[PREFIX]]/moduleC/module.modulemap",
// CHECK-NEXT: "command-line": [
// Module C doesn't need the VFS overlay.
// CHECK-NOT: "-ivfsoverlay"
// CHECK: ],
// CHECK-NEXT: "context-hash": "{{.*}}",
// CHECK-NEXT: "file-deps": [
// CHECK: ],
// CHECK-NEXT: "name": "C"
// CHECK-NEXT: }
// CHECK-NEXT: ],
// CHECK-NEXT: "translation-units": [
// CHECK: ]
// CHECK: }
//--- build/cdb.json.in
[{
"directory": "DIR",
"command": "clang -c DIR/tu.m -I DIR/moduleA -I DIR/moduleB -I DIR/moduleC
-fmodules -fmodules-cache-path=DIR/cache -fimplicit-module-maps -ivfsoverlay
DIR/build/vfs.yaml",
"file": "DIR/tu.m"
}]
//--- build/vfs.yaml.in
{
"version": 0,
"case-sensitive": "false",
"roots": [
{
"contents": [
{
"external-contents": "DIR/build/B.h",
"name": "B.h",
"type": "file"
}
],
"name": "DIR/moduleB",
"type": "directory"
}
]
}
//--- tu.m
@import A;
//--- moduleA/module.modulemap
module A { header "A.h" }
//--- moduleA/A.h
@import B;
@import C;
//--- moduleB/module.modulemap
module B { header "B.h" }
//--- build/B.h
//--- moduleC/module.modulemap
module C { header "C.h" }
//--- moduleC/C.h
```
https://github.com/llvm/llvm-project/pull/73734
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