rc: an interface-typed global initialized with a class object holds it (#656)

`let a: I = K.w` (a static field, another global, a field or an element)
gave the global no count of its own: claimGlobalInitializers looked
through casts and unions to the value a global is given, but not through
`ts.NewInterface`, the view a class object takes for an interface-typed
global. Giving either side a new value freed the block the other still
read (rc printed 999 for 1). A call's or a `new`'s reference
(`let a: I = mk()`, `let a: I = new V(8)`) was given back as a discarded
temporary at the end of the initializer, so the global was born pointing
at freed memory; under own too (`let a: I = mk()` read a freed block).

The initializer now looks through `ts.NewInterface` to the object.

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

Author: ASDAlexander77

tslang/lib/TypeScript/OwnedReturnConsumptionPass.cpp

@@ -875,7 +875,8 @@ class OwnedReturnConsumptionPass
     // The initializer region ends in `ts.GlobalResult`, a terminator, so a value given to it
     // straight is never released as a discarded temporary (§9.30): `let g = mk()` keeps the call's
     // +1. A value given to it through a view of the global's type is: `ts.Cast` to `C | null` or
-    // `Shared<T> | null`, `ts.OptionalValue` to `C | undefined`, `ts.CreateUnionInstance` - the view
+    // `Shared<T> | null`, `ts.OptionalValue` to `C | undefined`, `ts.CreateUnionInstance`,
+    // `ts.NewInterface` over a class object for an interface-typed global (`let g: I = mk()`) - the view
     // is the one use the producer has, and it is releasable, so the producer's reference was given
     // back at the end of the region and the global was born at count 0, pointing at freed memory
     // (#459; own spec 23.1 for handles).
@@ -920,6 +921,10 @@ class OwnedReturnConsumptionPass
                 {
                     value = createUnionInstanceOp.getIn();
                 }
+                else if (auto newInterfaceOp = mlir::dyn_cast<mlir_ts::NewInterfaceOp>(definingOp))
+                {
+                    value = newInterfaceOp.getThisVal();
+                }
                 else
                 {
                     break;

tslang/test/tester/CMakeLists.txt

@@ -399,6 +399,7 @@ tslang_add_test(NAME test-compile-00-array-length-valid COMMAND test-runner "${P
 tslang_add_test(NAME test-compile-00-const-interface-of-local COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00const_interface_of_local.ts")
 tslang_add_test(NAME test-compile-00-string-view-copy COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00string_view_copy.ts")
 tslang_add_test(NAME test-compile-00-global-copy-counted COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00global_copy_counted.ts")
+tslang_add_test(NAME test-compile-00-global-interface-initializer COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00global_interface_initializer.ts")
 tslang_add_test(NAME test-compile-00-c-string-copy COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00c_string_copy.ts")
 tslang_add_test(NAME test-compile-00-const-field-read COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00const_field_read.ts")
 tslang_add_test(NAME test-compile-00-const-element-read COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00const_element_read.ts")
@@ -983,6 +984,7 @@ tslang_add_test(NAME test-jit-00-array-length-valid COMMAND test-runner -jit "${
 tslang_add_test(NAME test-jit-00-const-interface-of-local COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00const_interface_of_local.ts")
 tslang_add_test(NAME test-jit-00-string-view-copy COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00string_view_copy.ts")
 tslang_add_test(NAME test-jit-00-global-copy-counted COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00global_copy_counted.ts")
+tslang_add_test(NAME test-jit-00-global-interface-initializer COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00global_interface_initializer.ts")
 tslang_add_test(NAME test-jit-00-c-string-copy COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00c_string_copy.ts")
 tslang_add_test(NAME test-jit-00-const-field-read COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00const_field_read.ts")
 tslang_add_test(NAME test-jit-00-const-element-read COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00const_element_read.ts")
@@ -1957,6 +1959,7 @@ set(TSLANG_CORPUS
     00const_interface_of_local.ts
     00string_view_copy.ts
     00global_copy_counted.ts
+    00global_interface_initializer.ts
     00c_string_copy.ts
     00const_field_read.ts
     00const_element_read.ts
@@ -3691,6 +3694,12 @@ foreach(kept_mm own rc none gc)
     tslang_add_test(NAME test-compile-${kept_mm}-own-global-kept-argument COMMAND test-runner -mm=${kept_mm} "${PROJECT_SOURCE_DIR}/test/tester/own/own_global_kept_argument.ts")
 endforeach()
 
+# An interface-typed global given a fresh class object owns it; the same program under every model.
+foreach(iface_mm own rc none gc)
+    tslang_add_test(NAME test-jit-${iface_mm}-own-global-interface-fresh COMMAND test-runner -jit -mm=${iface_mm} "${PROJECT_SOURCE_DIR}/test/tester/own/own_global_interface_fresh.ts")
+    tslang_add_test(NAME test-compile-${iface_mm}-own-global-interface-fresh COMMAND test-runner -mm=${iface_mm} "${PROJECT_SOURCE_DIR}/test/tester/own/own_global_interface_fresh.ts")
+endforeach()
+
 # A `let` given a new value after its value moved owns the new one (#528); the same program under
 # rc and gc (not none: nothing is freed there, and the loops would hold about 800 MB).
 foreach(reassign_mm rc gc)

tslang/test/tester/own/own_global_interface_fresh.ts

@@ -0,0 +1,50 @@
+// An interface-typed global given a fresh class object (`let a: I = mk()`, `let a: I = new V()`)
+// owns it. The object reaches the global through a view, `ts.NewInterface`, which hid it from the
+// global's initializer: the call's or the `new`'s reference was given back as a discarded
+// temporary at the end of the initializer, and the global was born pointing at freed memory
+// (own and rc). Each read follows allocations of the same size, so a freed block is reused.
+interface I {
+    x: number;
+    tag: string;
+}
+
+class V implements I {
+    tag = "";
+    constructor(public x: number) {
+        this.tag = "v" + x;
+    }
+}
+
+class Junk {
+    a = -1;
+    b = -2;
+    tag = "junk";
+}
+
+function churn() {
+    let keep: Junk[] = [];
+    for (let i = 0; i < 1000; i++) keep.push(new Junk());
+    return keep.length;
+}
+
+function mk(n: number) {
+    return new V(n);
+}
+
+let fromCall: I = mk(7);
+let fromNew: I = new V(8);
+const constFromCall: I = mk(9);
+
+function main() {
+    churn();
+    assert(fromCall.x == 7 && fromCall.tag == "v7", "a call's result");
+    assert(fromNew.x == 8 && fromNew.tag == "v8", "a new object");
+    assert(constFromCall.x == 9 && constFromCall.tag == "v9", "a const made by a call");
+
+    fromCall = new V(17);
+    fromNew = mk(18);
+    churn();
+    assert(fromCall.x == 17 && fromCall.tag == "v17", "the call's global reassigned");
+    assert(fromNew.x == 18 && fromNew.tag == "v18", "the new object's global reassigned");
+    print("done.");
+}

tslang/test/tester/tests/00global_interface_initializer.ts

@@ -0,0 +1,97 @@
+// An interface-typed global initialized with a class object (`let a: I = K.w`, `let a: I = mk()`)
+// holds the object through a view, `ts.NewInterface`. Under rc that view hid the object from the
+// global's initializer: a read of another global, a field or an element took no count, so giving
+// either side a new value freed the block the other still read; and a call's or a `new`'s
+// reference was given back as a discarded temporary at the end of the initializer, so the global
+// was born pointing at freed memory. Each read follows allocations of the same size, so a freed
+// block is reused.
+interface I {
+    x: number;
+    tag: string;
+}
+
+class V implements I {
+    tag = "";
+    constructor(public x: number) {
+        this.tag = "v" + x;
+    }
+}
+
+class H {
+    v = new V(3);
+}
+
+class K {
+    static w = new V(1);
+}
+
+class Junk {
+    a = -1;
+    b = -2;
+    tag = "junk";
+}
+
+function churn() {
+    let keep: Junk[] = [];
+    for (let i = 0; i < 1000; i++) keep.push(new Junk());
+    return keep.length;
+}
+
+function mk(n: number) {
+    return new V(n);
+}
+
+let G = new V(2);
+const h = new H();
+const arr = [new V(4)];
+
+// the interface global is given a new value: the source keeps its block
+let aStatic: I = K.w;
+let aGlobal: I = G;
+let aField: I = h.v;
+let aElement: I = arr[0];
+
+// the source is given a new value: the interface global keeps its block
+let G2 = new V(5);
+const h2 = new H();
+const arr2 = [new V(6)];
+let bGlobal: I = G2;
+const bConst: I = G2;
+let bField: I = h2.v;
+let bElement: I = arr2[0];
+
+// a fresh object: the global takes its reference
+let cCall: I = mk(7);
+let cNew: I = new V(8);
+
+function main() {
+    churn();
+    assert(cCall.x == 7 && cCall.tag == "v7", "a call's result");
+    assert(cNew.x == 8 && cNew.tag == "v8", "a new object");
+
+    aStatic = new V(11);
+    aGlobal = new V(12);
+    aField = new V(13);
+    aElement = new V(14);
+    churn();
+    assert(K.w.x == 1 && K.w.tag == "v1", "a static field read");
+    assert(G.x == 2 && G.tag == "v2", "a global read");
+    assert(h.v.x == 3 && h.v.tag == "v3", "a field read");
+    assert(arr[0].x == 4 && arr[0].tag == "v4", "an element read");
+
+    G2 = new V(15);
+    h2.v = new V(16);
+    arr2[0] = new V(17);
+    churn();
+    assert(bGlobal.x == 5 && bGlobal.tag == "v5", "a global read, the global reassigned");
+    assert(bConst.x == 5 && bConst.tag == "v5", "a const of a global, the global reassigned");
+    assert(bField.x == 3 && bField.tag == "v3", "a field read, the field reassigned");
+    assert(bElement.x == 6 && bElement.tag == "v6", "an element read, the element reassigned");
+
+    cCall = new V(18);
+    cNew = new V(19);
+    churn();
+    assert(cCall.x == 18 && cNew.x == 19, "the fresh objects' globals reassigned");
+    assert(aStatic.x == 11 && aGlobal.x == 12 && aField.x == 13 && aElement.x == 14, "the new values");
+    print("done.");
+}