[clang] [clang][scan-deps] Report a scanned TU's visible modules (PR #147969)

[Jan Svoboda via cfe-commits]

================
@@ -0,0 +1,72 @@
+// This test verifies that the modules visible to the translation unit are computed in dependency scanning.
+// "client" represents the translation unit that imports an explicit submodule, that only exports one other module. 
+// Thus, the dependencies of the top level module for the submodule differ from what is visible to the TU.
+
+// RUN: rm -rf %t
+// RUN: split-file %s %t
+// RUN: sed -e "s|DIR|%/t|g" %t/compile-commands.json.in > %t/compile-commands.json
+// RUN: clang-scan-deps -compilation-database %t/compile-commands.json \
+// RUN:   -j 1 -format experimental-full 2>&1 > %t/result.json
+// RUN: cat %t/result.json | sed 's:\\\\\?:/:g' | FileCheck %s -DPREFIX=%/t
+
+// CHECK:        "visible-clang-modules": [
+// CHECK-NEXT:     "A",
+// CHECK-NEXT:     "visible"
+// CHECK-NEXT:   ]
+
+//--- compile-commands.json.in
+[
+{
+  "directory": "DIR",
+  "command": "clang -c DIR/client.c -isysroot DIR/Sysroot -IDIR/Sysroot/usr/include -fmodules -fmodules-cache-path=DIR/module-cache -fimplicit-module-maps",
+  "file": "DIR/client.c"
+}
+]
+
+//--- Sysroot/usr/include/A/module.modulemap
+module A {
+  explicit module visibleToTU {
+    header "visibleToTU.h"
+  }
+  explicit module invisibleToTU {
+    header "invisibleToTU.h" 
+  }
+}
+//--- Sysroot/usr/include/A/visibleToTU.h
+#include <visible/visible.h>
+typedef int A_visibleToTU;
+
+//--- Sysroot/usr/include/A/invisibleToTU.h
+#include <invisible/invisible.h>
+typedef int A_invisibleToTU;
+
+//--- Sysroot/usr/include/invisible/module.modulemap
+module invisible {
+  umbrella "."
+}
+
+//--- Sysroot/usr/include/invisible/invisible.h
+typedef int invisible_t;
+
+//--- Sysroot/usr/include/visible/module.modulemap
+module visible {
+  umbrella "."
+}
+
+//--- Sysroot/usr/include/visible/visible.h
+#include <transitive/transitive.h>
+typedef int visible_t;
+
+//--- Sysroot/usr/include/transitive/module.modulemap
+module transitive {
+  umbrella "."
+}
+
+//--- Sysroot/usr/include/transitive/transitive.h
+typedef int transitive_t;
+
+//--- client.c
+#include <A/visibleToTU.h> 
+// Both decls are not visible, thus should fail to actually compile.
+transitive_t foo_t(void);
+invisible_t foo(void); 
----------------
jansvoboda11 wrote:

Adding this also fails to compile:
```c
visible_t foo_v(void);
```
I verified that by adding this to the test file:
```shell
// RUN: %deps-to-rsp %t/result.json --module-name=transitive > %t/transitive.rsp
// RUN: %deps-to-rsp %t/result.json --module-name=visible > %t/visible.rsp
// RUN: %deps-to-rsp %t/result.json --module-name=invisible > %t/invisible.rsp
// RUN: %deps-to-rsp %t/result.json --module-name=A > %t/A.rsp
// RUN: %deps-to-rsp %t/result.json --tu-index=0 > %t/tu.rsp

// RUN: %clang @%t/transitive.rsp
// RUN: %clang @%t/visible.rsp
// RUN: %clang @%t/invisible.rsp
// RUN: %clang @%t/A.rsp
// RUN: %clang @%t/tu.rsp
```
That seems unexpected based on the test description.

https://github.com/llvm/llvm-project/pull/147969