Fix bugzilla issue 24846 - atomicLoad does not work for class arguments with -preview=nosharedaccess

compiler/src/dmd/expressionsem.d

@@ -15136,6 +15136,27 @@ bool checkSharedAccess(Expression e, Scope* sc, bool returnRef = false)
     {
         return false;
     }
+    else if (sc._module.ident == Id.atomic && sc._module.parent !is null)
+    {
+        // Allow core.internal.atomic, it is an compiler implementation for a given platform module.
+        // It is then exposed by other modules such as core.atomic and core.stdc.atomic.
+        // This is available as long as druntime is on the import path and the platform supports that operation.
+
+        // https://issues.dlang.org/show_bug.cgi?id=24846
+
+        Package parent = sc._module.parent.isPackage();
+        if (parent !is null)
+        {
+            // This can be easily converted over to apply to core.atomic and core.internal.atomic
+            if (parent.ident == Id.internal)
+            {
+                parent = parent.parent.isPackage();
+
+                if (parent !is null && parent.ident == Id.core && parent.parent is null)
+                   return false;
+            }
+        }
+    }
 
     //printf("checkSharedAccess() `%s` returnRef: %d\n", e.toChars(), returnRef);
 

compiler/src/dmd/frontend.h

@@ -8606,6 +8606,7 @@ struct Id final
     static Identifier* va_start;
     static Identifier* std;
     static Identifier* core;
+    static Identifier* internal;
     static Identifier* config;
     static Identifier* c_complex_float;
     static Identifier* c_complex_double;

compiler/src/dmd/id.d

@@ -389,6 +389,7 @@ immutable Msgtable[] msgtable =
     // Builtin functions
     { "std" },
     { "core" },
+    { "internal" },
     { "config" },
     { "c_complex_float" },
     { "c_complex_double" },

compiler/test/compilable/atomic_loadstore_shared_classes.d

@@ -5,9 +5,14 @@ class Foo
 {
 }
 
+shared Foo toLoad;
+
 void oops()
 {
     auto f0 = new shared Foo;
     auto f1 = new shared Foo;
     atomicStore(f0, f1);
+
+    // https://issues.dlang.org/show_bug.cgi?id=24846
+    shared(Foo) f2 = atomicLoad(toLoad);
 }