Fix Issue 21651 - Unimported package doesn't error out when used as p…

changelog/fqn-bypass-deprecation.dd

@@ -0,0 +1,20 @@
+Deprecate a case of using fully-qualified names to bypass imports
+
+Since v2.084 it is no longer possible to bypass private imports by using fully-qualified names,
+this was deprecated in v2.071 but when fully-qualified names are used as a type
+(vs an expression) the code is accepted without any warning.
+
+Starting with this release the compiler will now properly deprecate the previous omitted case.
+
+The issue is best described in the following example:
+
+```d
+import std.algorithm;
+
+// deprecated in v2.071, error since v2.084
+auto a = std.range.Take!(int[]); // Error: undefined identifier `range` in package `std`...
+
+// now it's deprecated, will be error from v2.106
+std.range.Take!(int[]) s;
+
+````

src/dmd/todt.d

@@ -33,6 +33,7 @@ import dmd.errors;
 import dmd.expression;
 import dmd.func;
 import dmd.globals;
+import dmd.glue;
 import dmd.init;
 import dmd.mtype;
 import dmd.target;

src/dmd/typesem.d

@@ -28,7 +28,7 @@ import dmd.declaration;
 import dmd.denum;
 import dmd.dimport;
 import dmd.dmangle;
-import dmd.dmodule : Module;
+import dmd.dmodule;
 import dmd.dscope;
 import dmd.dstruct;
 import dmd.dsymbol;
@@ -255,10 +255,22 @@ private void resolveHelper(TypeQualified mt, const ref Loc loc, Scope* sc, Dsymb
         int flags = t is null ? SearchLocalsOnly : IgnorePrivateImports;
 
         Dsymbol sm = s.searchX(loc, sc, id, flags);
-        if (sm && !(sc.flags & SCOPE.ignoresymbolvisibility) && !symbolIsVisible(sc, sm))
+        if (sm)
         {
-            .error(loc, "`%s` is not visible from module `%s`", sm.toPrettyChars(), sc._module.toChars());
-            sm = null;
+            if (!(sc.flags & SCOPE.ignoresymbolvisibility) && !symbolIsVisible(sc, sm))
+            {
+                .error(loc, "`%s` is not visible from module `%s`", sm.toPrettyChars(), sc._module.toChars());
+                sm = null;
+            }
+            // Same check as in Expression.semanticY(DotIdExp)
+            else if (sm.isPackage() && checkAccess(sc, cast(Package)sm))
+            {
+                // @@@DEPRECATED_2.096@@@
+                // Should be an error in 2.106. Just remove the deprecation call
+                // and uncomment the null assignment
+                deprecation(loc, "%s %s is not accessible here, perhaps add 'static import %s;'", sm.kind(), sm.toPrettyChars(), sm.toPrettyChars());
+                //sm = null;
+            }
         }
         if (global.errors != errorsave)
         {

test/compilable/extra-files/serenity7190/core/Controller.d

@@ -3,6 +3,12 @@ class Controller {
         enum _s_pkg = __traits(parent, __traits(parent, __traits(parent, T))).stringof["package ".length .. $];
 
         enum _s_model = T.stringof[0 .. $-`Controller`.length] ~ `Model`;
+
+        import serenity7190.core.Model;
+        // expands to "import example7190.models.HomeModel;"
+        mixin(q{import } ~ _s_pkg ~ q{.models.} ~ _s_model ~ q{;});
+
+        // "enum _ = is(example7190.models.HomeModel.HomeModel : serenity7190.core.Model.Model);"
         mixin(q{enum _ = is(} ~ _s_pkg ~ q{.models.} ~ _s_model ~ q{.} ~ _s_model ~ q{ : serenity7190.core.Model.Model);});
     }
-}
+}

test/fail_compilation/ice10598.d

@@ -0,0 +1,10 @@
+// REQUIRED_ARGS: -de
+// EXTRA_SOURCES: imports/ice10598a.d imports/ice10598b.d
+/* TEST_OUTPUT:
+---
+fail_compilation/imports/ice10598a.d(5): Deprecation: module imports.ice10598b is not accessible here, perhaps add 'static import imports.ice10598b;'
+fail_compilation/imports/ice10598a.d(5): Deprecation: module imports.ice10598b is not accessible here, perhaps add 'static import imports.ice10598b;'
+---
+*/
+
+void main() {}

test/fail_compilation/imports/test21651b.d

@@ -0,0 +1,3 @@
+module imports.test21651b;
+
+alias T = int;

test/fail_compilation/test21651.d

@@ -0,0 +1,11 @@
+// REQUIRED_ARGS: -de
+// EXTRA_SOURCES: imports/test21651b.d
+/* TEST_OUTPUT:
+---
+fail_compilation/test21651.d(11): Deprecation: module imports.test21651b is not accessible here, perhaps add 'static import imports.test21651b;'
+---
+*/
+
+module imports.test21651;
+
+imports.test21651b.T a;