Fix #11660: wrong reports that block-scoped variable used before its … (#11692)

* Fix #11660: wrong reports that block-scoped variable used before its declaration

* Fix code style in checker.ts

* Add unit test for #11660

* Fix the unit test for #11660

src/compiler/checker.ts

@@ -591,7 +591,11 @@ namespace ts {
                     // nodes are in different files and order cannot be determines
                     return true;
                 }
-
+                // declaration is after usage
+                // can be legal if usage is deferred (i.e. inside function or in initializer of instance property)
+                if (isUsedInFunctionOrNonStaticProperty(usage)) {
+                    return true;
+                }
                 const sourceFiles = host.getSourceFiles();
                 return indexOf(sourceFiles, declarationFile) <= indexOf(sourceFiles, useFile);
             }
@@ -605,7 +609,8 @@ namespace ts {
 
             // declaration is after usage
             // can be legal if usage is deferred (i.e. inside function or in initializer of instance property)
-            return isUsedInFunctionOrNonStaticProperty(declaration, usage);
+            const container = getEnclosingBlockScopeContainer(declaration);
+            return isUsedInFunctionOrNonStaticProperty(usage, container);
 
             function isImmediatelyUsedInInitializerOfBlockScopedVariable(declaration: VariableDeclaration, usage: Node): boolean {
                 const container = getEnclosingBlockScopeContainer(declaration);
@@ -634,8 +639,7 @@ namespace ts {
                 return false;
             }
 
-            function isUsedInFunctionOrNonStaticProperty(declaration: Declaration, usage: Node): boolean {
-                const container = getEnclosingBlockScopeContainer(declaration);
+            function isUsedInFunctionOrNonStaticProperty(usage: Node, container?: Node): boolean {
                 let current = usage;
                 while (current) {
                     if (current === container) {

tests/baselines/reference/useBeforeDeclaration.js

@@ -0,0 +1,38 @@
+//// [tests/cases/compiler/useBeforeDeclaration.ts] ////
+
+//// [A.ts]
+
+namespace ts {
+    export function printVersion():void {
+        log("Version: " + sys.version);  // the call of sys.version is deferred, should not report an error.
+    }
+
+    export function log(info:string):void {
+
+    }
+}
+
+//// [B.ts]
+namespace ts {
+
+    export let sys:{version:string} = {version: "2.0.5"};
+
+}
+
+
+
+//// [test.js]
+var ts;
+(function (ts) {
+    function printVersion() {
+        log("Version: " + ts.sys.version); // the call of sys.version is deferred, should not report an error.
+    }
+    ts.printVersion = printVersion;
+    function log(info) {
+    }
+    ts.log = log;
+})(ts || (ts = {}));
+var ts;
+(function (ts) {
+    ts.sys = { version: "2.0.5" };
+})(ts || (ts = {}));

tests/baselines/reference/useBeforeDeclaration.symbols

@@ -0,0 +1,34 @@
+=== tests/cases/compiler/A.ts ===
+
+namespace ts {
+>ts : Symbol(ts, Decl(A.ts, 0, 0), Decl(B.ts, 0, 0))
+
+    export function printVersion():void {
+>printVersion : Symbol(printVersion, Decl(A.ts, 1, 14))
+
+        log("Version: " + sys.version);  // the call of sys.version is deferred, should not report an error.
+>log : Symbol(log, Decl(A.ts, 4, 5))
+>sys.version : Symbol(version, Decl(B.ts, 2, 20))
+>sys : Symbol(sys, Decl(B.ts, 2, 14))
+>version : Symbol(version, Decl(B.ts, 2, 20))
+    }
+
+    export function log(info:string):void {
+>log : Symbol(log, Decl(A.ts, 4, 5))
+>info : Symbol(info, Decl(A.ts, 6, 24))
+
+    }
+}
+
+=== tests/cases/compiler/B.ts ===
+namespace ts {
+>ts : Symbol(ts, Decl(A.ts, 0, 0), Decl(B.ts, 0, 0))
+
+    export let sys:{version:string} = {version: "2.0.5"};
+>sys : Symbol(sys, Decl(B.ts, 2, 14))
+>version : Symbol(version, Decl(B.ts, 2, 20))
+>version : Symbol(version, Decl(B.ts, 2, 39))
+
+}
+
+

tests/baselines/reference/useBeforeDeclaration.types

@@ -0,0 +1,39 @@
+=== tests/cases/compiler/A.ts ===
+
+namespace ts {
+>ts : typeof ts
+
+    export function printVersion():void {
+>printVersion : () => void
+
+        log("Version: " + sys.version);  // the call of sys.version is deferred, should not report an error.
+>log("Version: " + sys.version) : void
+>log : (info: string) => void
+>"Version: " + sys.version : string
+>"Version: " : "Version: "
+>sys.version : string
+>sys : { version: string; }
+>version : string
+    }
+
+    export function log(info:string):void {
+>log : (info: string) => void
+>info : string
+
+    }
+}
+
+=== tests/cases/compiler/B.ts ===
+namespace ts {
+>ts : typeof ts
+
+    export let sys:{version:string} = {version: "2.0.5"};
+>sys : { version: string; }
+>version : string
+>{version: "2.0.5"} : { version: string; }
+>version : string
+>"2.0.5" : "2.0.5"
+
+}
+
+

tests/cases/compiler/useBeforeDeclaration.ts

@@ -0,0 +1,20 @@
+// @outFile: test.js
+
+// @fileName: A.ts
+namespace ts {
+    export function printVersion():void {
+        log("Version: " + sys.version);  // the call of sys.version is deferred, should not report an error.
+    }
+
+    export function log(info:string):void {
+
+    }
+}
+
+// @fileName: B.ts
+namespace ts {
+
+    export let sys:{version:string} = {version: "2.0.5"};
+
+}
+