Fix JS merge crashes from lovefield (#27989)

1. Merge enum with expando.
2. Merge enum member with property assignment.
3. Merge interface-declared method declaration with
prototype-property-assignment method declaration.

The reason that the enum merges crash is that getTypeOfSymbol assumes
that symbol flags are (basically) mutually exclusive. This assumption is
shredded, badly, for JS merges.

One fix is to drop the assumption of exclusivity and instead order cases
by least to most likely. This has the highest chance of working, but is
also slow, since you would prefer to order cases by most likely *first*,
not *last*.

The other fix, which is what I did here, is to add a last-chance
re-dispatch at the bottom of
`getTypeOfVariableOrParameterOrPropertyWorker`. This dispatch uses the
valueDeclaration instead of the symbol flags.

src/compiler/checker.ts

@@ -2214,6 +2214,9 @@ namespace ts {
 
         function getDeclarationOfJSPrototypeContainer(symbol: Symbol) {
             const decl = symbol.parent!.valueDeclaration;
+            if (!decl) {
+                return undefined;
+            }
             const initializer = isAssignmentDeclaration(decl) ? getAssignedExpandoInitializer(decl) :
                 hasOnlyExpressionInitializer(decl) ? getDeclaredExpandoInitializer(decl) :
                 undefined;
@@ -5241,6 +5244,14 @@ namespace ts {
                      || isBindingElement(declaration)) {
                 type = getWidenedTypeForVariableLikeDeclaration(declaration, /*includeOptionality*/ true);
             }
+            // getTypeOfSymbol dispatches some JS merges incorrectly because their symbol flags are not mutually exclusive.
+            // Re-dispatch based on valueDeclaration.kind instead.
+            else if (isEnumDeclaration(declaration)) {
+                type = getTypeOfFuncClassEnumModule(symbol);
+            }
+            else if (isEnumMember(declaration)) {
+                type = getTypeOfEnumMember(symbol);
+            }
             else {
                 return Debug.fail("Unhandled declaration kind! " + Debug.showSyntaxKind(declaration) + " for " + Debug.showSymbol(symbol));
             }

tests/baselines/reference/enumMergeWithExpando.errors.txt

@@ -0,0 +1,19 @@
+tests/cases/conformance/salsa/enums.js(2,10): error TS2540: Cannot assign to 'DESC' because it is a constant or a read-only property.
+tests/cases/conformance/salsa/enums.js(3,10): error TS2540: Cannot assign to 'ASC' because it is a constant or a read-only property.
+
+
+==== tests/cases/conformance/salsa/lovefield-ts.d.ts (0 errors) ====
+    // bug #27352, crashes from github.com/google/lovefield
+    declare namespace lf {
+        export enum Order { ASC, DESC }
+    }
+    
+==== tests/cases/conformance/salsa/enums.js (2 errors) ====
+    lf.Order = {}
+    lf.Order.DESC = 0;
+             ~~~~
+!!! error TS2540: Cannot assign to 'DESC' because it is a constant or a read-only property.
+    lf.Order.ASC = 1;
+             ~~~
+!!! error TS2540: Cannot assign to 'ASC' because it is a constant or a read-only property.
+    

tests/baselines/reference/enumMergeWithExpando.symbols

@@ -0,0 +1,31 @@
+=== tests/cases/conformance/salsa/lovefield-ts.d.ts ===
+// bug #27352, crashes from github.com/google/lovefield
+declare namespace lf {
+>lf : Symbol(lf, Decl(lovefield-ts.d.ts, 0, 0), Decl(enums.js, 0, 0), Decl(enums.js, 0, 13))
+
+    export enum Order { ASC, DESC }
+>Order : Symbol(Order, Decl(lovefield-ts.d.ts, 1, 22), Decl(enums.js, 0, 0), Decl(enums.js, 1, 3))
+>ASC : Symbol(Order.ASC, Decl(lovefield-ts.d.ts, 2, 23), Decl(enums.js, 1, 18))
+>DESC : Symbol(Order.DESC, Decl(lovefield-ts.d.ts, 2, 28), Decl(enums.js, 0, 13))
+}
+
+=== tests/cases/conformance/salsa/enums.js ===
+lf.Order = {}
+>lf.Order : Symbol(lf.Order, Decl(lovefield-ts.d.ts, 1, 22), Decl(enums.js, 0, 0), Decl(enums.js, 1, 3))
+>lf : Symbol(lf, Decl(lovefield-ts.d.ts, 0, 0), Decl(enums.js, 0, 0), Decl(enums.js, 0, 13))
+>Order : Symbol(lf.Order, Decl(lovefield-ts.d.ts, 1, 22), Decl(enums.js, 0, 0), Decl(enums.js, 1, 3))
+
+lf.Order.DESC = 0;
+>lf.Order.DESC : Symbol(lf.Order.DESC, Decl(lovefield-ts.d.ts, 2, 28), Decl(enums.js, 0, 13))
+>lf.Order : Symbol(lf.Order, Decl(lovefield-ts.d.ts, 1, 22), Decl(enums.js, 0, 0), Decl(enums.js, 1, 3))
+>lf : Symbol(lf, Decl(lovefield-ts.d.ts, 0, 0), Decl(enums.js, 0, 0), Decl(enums.js, 0, 13))
+>Order : Symbol(lf.Order, Decl(lovefield-ts.d.ts, 1, 22), Decl(enums.js, 0, 0), Decl(enums.js, 1, 3))
+>DESC : Symbol(lf.Order.DESC, Decl(lovefield-ts.d.ts, 2, 28), Decl(enums.js, 0, 13))
+
+lf.Order.ASC = 1;
+>lf.Order.ASC : Symbol(lf.Order.ASC, Decl(lovefield-ts.d.ts, 2, 23), Decl(enums.js, 1, 18))
+>lf.Order : Symbol(lf.Order, Decl(lovefield-ts.d.ts, 1, 22), Decl(enums.js, 0, 0), Decl(enums.js, 1, 3))
+>lf : Symbol(lf, Decl(lovefield-ts.d.ts, 0, 0), Decl(enums.js, 0, 0), Decl(enums.js, 0, 13))
+>Order : Symbol(lf.Order, Decl(lovefield-ts.d.ts, 1, 22), Decl(enums.js, 0, 0), Decl(enums.js, 1, 3))
+>ASC : Symbol(lf.Order.ASC, Decl(lovefield-ts.d.ts, 2, 23), Decl(enums.js, 1, 18))
+

tests/baselines/reference/enumMergeWithExpando.types

@@ -0,0 +1,37 @@
+=== tests/cases/conformance/salsa/lovefield-ts.d.ts ===
+// bug #27352, crashes from github.com/google/lovefield
+declare namespace lf {
+>lf : typeof lf
+
+    export enum Order { ASC, DESC }
+>Order : Order
+>ASC : Order
+>DESC : Order
+}
+
+=== tests/cases/conformance/salsa/enums.js ===
+lf.Order = {}
+>lf.Order = {} : typeof lf.Order
+>lf.Order : typeof lf.Order
+>lf : typeof lf
+>Order : typeof lf.Order
+>{} : {}
+
+lf.Order.DESC = 0;
+>lf.Order.DESC = 0 : 0
+>lf.Order.DESC : any
+>lf.Order : typeof lf.Order
+>lf : typeof lf
+>Order : typeof lf.Order
+>DESC : any
+>0 : 0
+
+lf.Order.ASC = 1;
+>lf.Order.ASC = 1 : 1
+>lf.Order.ASC : any
+>lf.Order : typeof lf.Order
+>lf : typeof lf
+>Order : typeof lf.Order
+>ASC : any
+>1 : 1
+

tests/baselines/reference/prototypePropertyAssignmentMergeWithInterfaceMethod.errors.txt

@@ -0,0 +1,40 @@
+tests/cases/conformance/salsa/lovefield-ts.d.ts(4,19): error TS2503: Cannot find namespace 'query'.
+tests/cases/conformance/salsa/lovefield-ts.d.ts(5,24): error TS2503: Cannot find namespace 'schema'.
+tests/cases/conformance/salsa/lovefield-ts.d.ts(7,25): error TS2503: Cannot find namespace 'query'.
+tests/cases/conformance/salsa/lovefield-ts.d.ts(9,14): error TS2304: Cannot find name 'TransactionStats'.
+tests/cases/conformance/salsa/lovefield.js(3,23): error TS2694: Namespace 'lf' has no exported member 'schema'.
+tests/cases/conformance/salsa/lovefield.js(4,14): error TS2304: Cannot find name 'IThenable'.
+
+
+==== tests/cases/conformance/salsa/lovefield-ts.d.ts (4 errors) ====
+    // bug #27352, crashes from github.com/google/lovefield
+    declare namespace lf {
+      export interface Transaction {
+        attach(query: query.Builder): Promise<Array<Object>>
+                      ~~~~~
+!!! error TS2503: Cannot find namespace 'query'.
+        begin(scope: Array<schema.Table>): Promise<void>
+                           ~~~~~~
+!!! error TS2503: Cannot find namespace 'schema'.
+        commit(): Promise<void>
+        exec(queries: Array<query.Builder>): Promise<Array<Array<Object>>>
+                            ~~~~~
+!!! error TS2503: Cannot find namespace 'query'.
+        rollback(): Promise<void>
+        stats(): TransactionStats
+                 ~~~~~~~~~~~~~~~~
+!!! error TS2304: Cannot find name 'TransactionStats'.
+      }
+    }
+==== tests/cases/conformance/salsa/lovefield.js (2 errors) ====
+    lf.Transaction = function() {};
+    /**
+     * @param {!Array<!lf.schema.Table>} scope
+                          ~~~~~~
+!!! error TS2694: Namespace 'lf' has no exported member 'schema'.
+     * @return {!IThenable}
+                 ~~~~~~~~~
+!!! error TS2304: Cannot find name 'IThenable'.
+     */
+    lf.Transaction.prototype.begin = function(scope) {};
+    

tests/baselines/reference/prototypePropertyAssignmentMergeWithInterfaceMethod.symbols

@@ -0,0 +1,61 @@
+=== tests/cases/conformance/salsa/lovefield-ts.d.ts ===
+// bug #27352, crashes from github.com/google/lovefield
+declare namespace lf {
+>lf : Symbol(lf, Decl(lovefield-ts.d.ts, 0, 0), Decl(lovefield.js, 0, 0))
+
+  export interface Transaction {
+>Transaction : Symbol(Transaction, Decl(lovefield-ts.d.ts, 1, 22), Decl(lovefield.js, 0, 0))
+
+    attach(query: query.Builder): Promise<Array<Object>>
+>attach : Symbol(Transaction.attach, Decl(lovefield-ts.d.ts, 2, 32))
+>query : Symbol(query, Decl(lovefield-ts.d.ts, 3, 11))
+>Promise : Symbol(Promise, Decl(lib.es5.d.ts, --, --))
+>Array : Symbol(Array, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>Object : Symbol(Object, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+
+    begin(scope: Array<schema.Table>): Promise<void>
+>begin : Symbol(Transaction.begin, Decl(lovefield-ts.d.ts, 3, 56), Decl(lovefield.js, 0, 31))
+>scope : Symbol(scope, Decl(lovefield-ts.d.ts, 4, 10))
+>Array : Symbol(Array, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>Promise : Symbol(Promise, Decl(lib.es5.d.ts, --, --))
+
+    commit(): Promise<void>
+>commit : Symbol(Transaction.commit, Decl(lovefield-ts.d.ts, 4, 52))
+>Promise : Symbol(Promise, Decl(lib.es5.d.ts, --, --))
+
+    exec(queries: Array<query.Builder>): Promise<Array<Array<Object>>>
+>exec : Symbol(Transaction.exec, Decl(lovefield-ts.d.ts, 5, 27))
+>queries : Symbol(queries, Decl(lovefield-ts.d.ts, 6, 9))
+>Array : Symbol(Array, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>Promise : Symbol(Promise, Decl(lib.es5.d.ts, --, --))
+>Array : Symbol(Array, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>Array : Symbol(Array, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>Object : Symbol(Object, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+
+    rollback(): Promise<void>
+>rollback : Symbol(Transaction.rollback, Decl(lovefield-ts.d.ts, 6, 70))
+>Promise : Symbol(Promise, Decl(lib.es5.d.ts, --, --))
+
+    stats(): TransactionStats
+>stats : Symbol(Transaction.stats, Decl(lovefield-ts.d.ts, 7, 29))
+  }
+}
+=== tests/cases/conformance/salsa/lovefield.js ===
+lf.Transaction = function() {};
+>lf.Transaction : Symbol(lf.Transaction, Decl(lovefield-ts.d.ts, 1, 22), Decl(lovefield.js, 0, 0))
+>lf : Symbol(lf, Decl(lovefield-ts.d.ts, 0, 0), Decl(lovefield.js, 0, 0))
+>Transaction : Symbol(lf.Transaction, Decl(lovefield-ts.d.ts, 1, 22), Decl(lovefield.js, 0, 0))
+
+/**
+ * @param {!Array<!lf.schema.Table>} scope
+ * @return {!IThenable}
+ */
+lf.Transaction.prototype.begin = function(scope) {};
+>lf.Transaction.prototype : Symbol(lf.Transaction.begin, Decl(lovefield-ts.d.ts, 3, 56), Decl(lovefield.js, 0, 31))
+>lf.Transaction : Symbol(lf.Transaction, Decl(lovefield-ts.d.ts, 1, 22), Decl(lovefield.js, 0, 0))
+>lf : Symbol(lf, Decl(lovefield-ts.d.ts, 0, 0), Decl(lovefield.js, 0, 0))
+>Transaction : Symbol(lf.Transaction, Decl(lovefield-ts.d.ts, 1, 22), Decl(lovefield.js, 0, 0))
+>prototype : Symbol(Function.prototype, Decl(lib.es5.d.ts, --, --))
+>begin : Symbol(lf.Transaction.begin, Decl(lovefield-ts.d.ts, 3, 56), Decl(lovefield.js, 0, 31))
+>scope : Symbol(scope, Decl(lovefield.js, 5, 42))
+

tests/baselines/reference/prototypePropertyAssignmentMergeWithInterfaceMethod.types

@@ -0,0 +1,53 @@
+=== tests/cases/conformance/salsa/lovefield-ts.d.ts ===
+// bug #27352, crashes from github.com/google/lovefield
+declare namespace lf {
+  export interface Transaction {
+    attach(query: query.Builder): Promise<Array<Object>>
+>attach : (query: any) => Promise<Object[]>
+>query : any
+>query : any
+
+    begin(scope: Array<schema.Table>): Promise<void>
+>begin : (scope: any[]) => Promise<void>
+>scope : any[]
+>schema : any
+
+    commit(): Promise<void>
+>commit : () => Promise<void>
+
+    exec(queries: Array<query.Builder>): Promise<Array<Array<Object>>>
+>exec : (queries: any[]) => Promise<Object[][]>
+>queries : any[]
+>query : any
+
+    rollback(): Promise<void>
+>rollback : () => Promise<void>
+
+    stats(): TransactionStats
+>stats : () => any
+  }
+}
+=== tests/cases/conformance/salsa/lovefield.js ===
+lf.Transaction = function() {};
+>lf.Transaction = function() {} : typeof Transaction
+>lf.Transaction : typeof Transaction
+>lf : typeof lf
+>Transaction : typeof Transaction
+>function() {} : typeof Transaction
+
+/**
+ * @param {!Array<!lf.schema.Table>} scope
+ * @return {!IThenable}
+ */
+lf.Transaction.prototype.begin = function(scope) {};
+>lf.Transaction.prototype.begin = function(scope) {} : (scope: any[]) => any
+>lf.Transaction.prototype.begin : any
+>lf.Transaction.prototype : any
+>lf.Transaction : typeof Transaction
+>lf : typeof lf
+>Transaction : typeof Transaction
+>prototype : any
+>begin : any
+>function(scope) {} : (scope: any[]) => any
+>scope : any[]
+

tests/cases/conformance/salsa/enumMergeWithExpando.ts

@@ -0,0 +1,13 @@
+// @noEmit: true
+// @allowJs: true
+// @checkJs: true
+// @Filename: lovefield-ts.d.ts
+// bug #27352, crashes from github.com/google/lovefield
+declare namespace lf {
+    export enum Order { ASC, DESC }
+}
+
+// @Filename: enums.js
+lf.Order = {}
+lf.Order.DESC = 0;
+lf.Order.ASC = 1;

tests/cases/conformance/salsa/prototypePropertyAssignmentMergeWithInterfaceMethod.ts

@@ -0,0 +1,22 @@
+// @noEmit: true
+// @allowJs: true
+// @checkJs: true
+// @Filename: lovefield-ts.d.ts
+// bug #27352, crashes from github.com/google/lovefield
+declare namespace lf {
+  export interface Transaction {
+    attach(query: query.Builder): Promise<Array<Object>>
+    begin(scope: Array<schema.Table>): Promise<void>
+    commit(): Promise<void>
+    exec(queries: Array<query.Builder>): Promise<Array<Array<Object>>>
+    rollback(): Promise<void>
+    stats(): TransactionStats
+  }
+}
+// @Filename: lovefield.js
+lf.Transaction = function() {};
+/**
+ * @param {!Array<!lf.schema.Table>} scope
+ * @return {!IThenable}
+ */
+lf.Transaction.prototype.begin = function(scope) {};