From 00ebf59b500d064524af5ddfef87b6c45b53e655 Mon Sep 17 00:00:00 2001
From: Nathan Shively-Sanders <nathansa@microsoft.com>
Date: Thu, 13 Oct 2016 16:26:44 -0700
Subject: [PATCH 1/9] Use same literal comparison rules for switch/===

switch was missing the rule for converting literal types to the literal
base type if needed.
---
 src/compiler/checker.ts | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 30a0bbd2042c8..6df09cca70493 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -16584,7 +16584,7 @@ namespace ts {
             let firstDefaultClause: CaseOrDefaultClause;
             let hasDuplicateDefaultClause = false;
 
-            const expressionType = checkExpression(node.expression);
+            let expressionType = checkExpression(node.expression);
             forEach(node.caseBlock.clauses, clause => {
                 // Grammar check for duplicate default clauses, skip if we already report duplicate default clause
                 if (clause.kind === SyntaxKind.DefaultClause && !hasDuplicateDefaultClause) {
@@ -16605,7 +16605,13 @@ namespace ts {
                     // TypeScript 1.0 spec (April 2014): 5.9
                     // In a 'switch' statement, each 'case' expression must be of a type that is comparable
                     // to or from the type of the 'switch' expression.
-                    const caseType = checkExpression(caseClause.expression);
+                    let caseType = checkExpression(caseClause.expression);
+                    const expressionIsLiteral = isLiteralType(expressionType);
+                    const caseIsLiteral = isLiteralType(caseType);
+                    if (!expressionIsLiteral || !caseIsLiteral) {
+                        expressionType = expressionIsLiteral ? getBaseTypeOfLiteralType(expressionType) : expressionType;
+                        caseType = caseIsLiteral ? getBaseTypeOfLiteralType(caseType) : caseType;
+                    }
                     if (!isTypeEqualityComparableTo(expressionType, caseType)) {
                         // expressionType is not comparable to caseType, try the reversed check and report errors if it fails
                         checkTypeComparableTo(caseType, expressionType, caseClause.expression, /*headMessage*/ undefined);

From 982abc29442fc145e9364aa7fad510c15f1008ac Mon Sep 17 00:00:00 2001
From: Nathan Shively-Sanders <nathansa@microsoft.com>
Date: Thu, 13 Oct 2016 16:29:35 -0700
Subject: [PATCH 2/9] Add switch comparability test and update baselines

---
 .../switchAssignmentCompat.errors.txt         |  4 +--
 .../switchCaseCircularRefeference.errors.txt  | 10 +++----
 ...itchCasesExpressionTypeMismatch.errors.txt | 17 +++++------
 .../switchComparableCompatForBrands.js        | 29 +++++++++++++++++++
 .../switchComparableCompatForBrands.symbols   | 22 ++++++++++++++
 .../switchComparableCompatForBrands.types     | 26 +++++++++++++++++
 .../switchComparableCompatForBrands.ts        | 13 +++++++++
 7 files changed, 103 insertions(+), 18 deletions(-)
 create mode 100644 tests/baselines/reference/switchComparableCompatForBrands.js
 create mode 100644 tests/baselines/reference/switchComparableCompatForBrands.symbols
 create mode 100644 tests/baselines/reference/switchComparableCompatForBrands.types
 create mode 100644 tests/cases/compiler/switchComparableCompatForBrands.ts

diff --git a/tests/baselines/reference/switchAssignmentCompat.errors.txt b/tests/baselines/reference/switchAssignmentCompat.errors.txt
index 46c89fa5b52d2..747a1035b6846 100644
--- a/tests/baselines/reference/switchAssignmentCompat.errors.txt
+++ b/tests/baselines/reference/switchAssignmentCompat.errors.txt
@@ -1,4 +1,4 @@
-tests/cases/compiler/switchAssignmentCompat.ts(4,10): error TS2678: Type 'typeof Foo' is not comparable to type '0'.
+tests/cases/compiler/switchAssignmentCompat.ts(4,10): error TS2678: Type 'typeof Foo' is not comparable to type 'number'.
 
 
 ==== tests/cases/compiler/switchAssignmentCompat.ts (1 errors) ====
@@ -7,6 +7,6 @@ tests/cases/compiler/switchAssignmentCompat.ts(4,10): error TS2678: Type 'typeof
     switch (0) {
         case Foo: break; // Error expected
              ~~~
-!!! error TS2678: Type 'typeof Foo' is not comparable to type '0'.
+!!! error TS2678: Type 'typeof Foo' is not comparable to type 'number'.
     }
     
\ No newline at end of file
diff --git a/tests/baselines/reference/switchCaseCircularRefeference.errors.txt b/tests/baselines/reference/switchCaseCircularRefeference.errors.txt
index 9ee571de468ce..bc576f8e723b8 100644
--- a/tests/baselines/reference/switchCaseCircularRefeference.errors.txt
+++ b/tests/baselines/reference/switchCaseCircularRefeference.errors.txt
@@ -1,6 +1,5 @@
-tests/cases/compiler/switchCaseCircularRefeference.ts(5,10): error TS2678: Type '{ a: "A"; b: any; } | { a: "C"; e: any; }' is not comparable to type '"A" | "C"'.
-  Type '{ a: "C"; e: any; }' is not comparable to type '"A" | "C"'.
-    Type '{ a: "C"; e: any; }' is not comparable to type '"C"'.
+tests/cases/compiler/switchCaseCircularRefeference.ts(5,10): error TS2678: Type '{ a: "A"; b: any; } | { a: "C"; e: any; }' is not comparable to type 'string'.
+  Type '{ a: "C"; e: any; }' is not comparable to type 'string'.
 
 
 ==== tests/cases/compiler/switchCaseCircularRefeference.ts (1 errors) ====
@@ -10,9 +9,8 @@ tests/cases/compiler/switchCaseCircularRefeference.ts(5,10): error TS2678: Type
         switch (x.a) {
         case x:
              ~
-!!! error TS2678: Type '{ a: "A"; b: any; } | { a: "C"; e: any; }' is not comparable to type '"A" | "C"'.
-!!! error TS2678:   Type '{ a: "C"; e: any; }' is not comparable to type '"A" | "C"'.
-!!! error TS2678:     Type '{ a: "C"; e: any; }' is not comparable to type '"C"'.
+!!! error TS2678: Type '{ a: "A"; b: any; } | { a: "C"; e: any; }' is not comparable to type 'string'.
+!!! error TS2678:   Type '{ a: "C"; e: any; }' is not comparable to type 'string'.
             break;
         }
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/switchCasesExpressionTypeMismatch.errors.txt b/tests/baselines/reference/switchCasesExpressionTypeMismatch.errors.txt
index 3ea12e2460f65..26d39efef48ec 100644
--- a/tests/baselines/reference/switchCasesExpressionTypeMismatch.errors.txt
+++ b/tests/baselines/reference/switchCasesExpressionTypeMismatch.errors.txt
@@ -1,25 +1,22 @@
-tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(4,10): error TS2678: Type 'typeof Foo' is not comparable to type '0'.
-tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(5,10): error TS2678: Type '"sss"' is not comparable to type '0'.
-tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(6,10): error TS2678: Type '123' is not comparable to type '0'.
-tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(7,10): error TS2678: Type 'true' is not comparable to type '0'.
+tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(4,10): error TS2678: Type 'typeof Foo' is not comparable to type 'number'.
+tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(5,10): error TS2678: Type 'string' is not comparable to type 'number'.
+tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(7,10): error TS2678: Type 'boolean' is not comparable to type 'number'.
 
 
-==== tests/cases/compiler/switchCasesExpressionTypeMismatch.ts (4 errors) ====
+==== tests/cases/compiler/switchCasesExpressionTypeMismatch.ts (3 errors) ====
     class Foo { }
     
     switch (0) {
         case Foo: break;    // Error
              ~~~
-!!! error TS2678: Type 'typeof Foo' is not comparable to type '0'.
+!!! error TS2678: Type 'typeof Foo' is not comparable to type 'number'.
         case "sss": break;  // Error
              ~~~~~
-!!! error TS2678: Type '"sss"' is not comparable to type '0'.
+!!! error TS2678: Type 'string' is not comparable to type 'number'.
         case 123: break;    // No Error
-             ~~~
-!!! error TS2678: Type '123' is not comparable to type '0'.
         case true: break;   // Error
              ~~~~
-!!! error TS2678: Type 'true' is not comparable to type '0'.
+!!! error TS2678: Type 'boolean' is not comparable to type 'number'.
     }
     
     var s: any = 0;
diff --git a/tests/baselines/reference/switchComparableCompatForBrands.js b/tests/baselines/reference/switchComparableCompatForBrands.js
new file mode 100644
index 0000000000000..316edfc9c31b1
--- /dev/null
+++ b/tests/baselines/reference/switchComparableCompatForBrands.js
@@ -0,0 +1,29 @@
+//// [switchComparableCompatForBrands.ts]
+class MyBrand
+{
+    private _a: number;
+}
+
+function test(strInput: string & MyBrand) {
+    switch(strInput)
+    {
+        case "a":
+        return 1;
+    }
+    return 0;
+}
+
+
+//// [switchComparableCompatForBrands.js]
+var MyBrand = (function () {
+    function MyBrand() {
+    }
+    return MyBrand;
+}());
+function test(strInput) {
+    switch (strInput) {
+        case "a":
+            return 1;
+    }
+    return 0;
+}
diff --git a/tests/baselines/reference/switchComparableCompatForBrands.symbols b/tests/baselines/reference/switchComparableCompatForBrands.symbols
new file mode 100644
index 0000000000000..adf6a5174adf3
--- /dev/null
+++ b/tests/baselines/reference/switchComparableCompatForBrands.symbols
@@ -0,0 +1,22 @@
+=== tests/cases/compiler/switchComparableCompatForBrands.ts ===
+class MyBrand
+>MyBrand : Symbol(MyBrand, Decl(switchComparableCompatForBrands.ts, 0, 0))
+{
+    private _a: number;
+>_a : Symbol(MyBrand._a, Decl(switchComparableCompatForBrands.ts, 1, 1))
+}
+
+function test(strInput: string & MyBrand) {
+>test : Symbol(test, Decl(switchComparableCompatForBrands.ts, 3, 1))
+>strInput : Symbol(strInput, Decl(switchComparableCompatForBrands.ts, 5, 14))
+>MyBrand : Symbol(MyBrand, Decl(switchComparableCompatForBrands.ts, 0, 0))
+
+    switch(strInput)
+>strInput : Symbol(strInput, Decl(switchComparableCompatForBrands.ts, 5, 14))
+    {
+        case "a":
+        return 1;
+    }
+    return 0;
+}
+
diff --git a/tests/baselines/reference/switchComparableCompatForBrands.types b/tests/baselines/reference/switchComparableCompatForBrands.types
new file mode 100644
index 0000000000000..5e479ee29dc2e
--- /dev/null
+++ b/tests/baselines/reference/switchComparableCompatForBrands.types
@@ -0,0 +1,26 @@
+=== tests/cases/compiler/switchComparableCompatForBrands.ts ===
+class MyBrand
+>MyBrand : MyBrand
+{
+    private _a: number;
+>_a : number
+}
+
+function test(strInput: string & MyBrand) {
+>test : (strInput: string & MyBrand) => 1 | 0
+>strInput : string & MyBrand
+>MyBrand : MyBrand
+
+    switch(strInput)
+>strInput : string & MyBrand
+    {
+        case "a":
+>"a" : "a"
+
+        return 1;
+>1 : 1
+    }
+    return 0;
+>0 : 0
+}
+
diff --git a/tests/cases/compiler/switchComparableCompatForBrands.ts b/tests/cases/compiler/switchComparableCompatForBrands.ts
new file mode 100644
index 0000000000000..4b90db40e1db8
--- /dev/null
+++ b/tests/cases/compiler/switchComparableCompatForBrands.ts
@@ -0,0 +1,13 @@
+class MyBrand
+{
+    private _a: number;
+}
+
+function test(strInput: string & MyBrand) {
+    switch(strInput)
+    {
+        case "a":
+        return 1;
+    }
+    return 0;
+}

From 0168f67f63c1180caca7c1d3500773e64580d952 Mon Sep 17 00:00:00 2001
From: Nathan Shively-Sanders <nathansa@microsoft.com>
Date: Fri, 14 Oct 2016 08:55:01 -0700
Subject: [PATCH 3/9] Push eitherIsNotLiteral check into
 isTypeEqualityComparableTo

Since all callers need this check -- it's how equality is supposed to
work everywhere.
---
 src/compiler/checker.ts | 22 ++++++++--------------
 1 file changed, 8 insertions(+), 14 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 6df09cca70493..24f71ee41ed13 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -13532,6 +13532,12 @@ namespace ts {
         }
 
         function isTypeEqualityComparableTo(source: Type, target: Type) {
+            const sourceIsLiteral = isLiteralType(source);
+            const targetIsLiteral = isLiteralType(target);
+            if (!sourceIsLiteral || !targetIsLiteral) {
+                source = sourceIsLiteral ? getBaseTypeOfLiteralType(source) : source;
+                target = targetIsLiteral ? getBaseTypeOfLiteralType(target) : target;
+            }
             return (target.flags & TypeFlags.Nullable) !== 0 || isTypeComparableTo(source, target);
         }
 
@@ -13672,12 +13678,6 @@ namespace ts {
                 case SyntaxKind.ExclamationEqualsToken:
                 case SyntaxKind.EqualsEqualsEqualsToken:
                 case SyntaxKind.ExclamationEqualsEqualsToken:
-                    const leftIsLiteral = isLiteralType(leftType);
-                    const rightIsLiteral = isLiteralType(rightType);
-                    if (!leftIsLiteral || !rightIsLiteral) {
-                        leftType = leftIsLiteral ? getBaseTypeOfLiteralType(leftType) : leftType;
-                        rightType = rightIsLiteral ? getBaseTypeOfLiteralType(rightType) : rightType;
-                    }
                     if (!isTypeEqualityComparableTo(leftType, rightType) && !isTypeEqualityComparableTo(rightType, leftType)) {
                         reportOperatorError();
                     }
@@ -16584,7 +16584,7 @@ namespace ts {
             let firstDefaultClause: CaseOrDefaultClause;
             let hasDuplicateDefaultClause = false;
 
-            let expressionType = checkExpression(node.expression);
+            const expressionType = checkExpression(node.expression);
             forEach(node.caseBlock.clauses, clause => {
                 // Grammar check for duplicate default clauses, skip if we already report duplicate default clause
                 if (clause.kind === SyntaxKind.DefaultClause && !hasDuplicateDefaultClause) {
@@ -16605,13 +16605,7 @@ namespace ts {
                     // TypeScript 1.0 spec (April 2014): 5.9
                     // In a 'switch' statement, each 'case' expression must be of a type that is comparable
                     // to or from the type of the 'switch' expression.
-                    let caseType = checkExpression(caseClause.expression);
-                    const expressionIsLiteral = isLiteralType(expressionType);
-                    const caseIsLiteral = isLiteralType(caseType);
-                    if (!expressionIsLiteral || !caseIsLiteral) {
-                        expressionType = expressionIsLiteral ? getBaseTypeOfLiteralType(expressionType) : expressionType;
-                        caseType = caseIsLiteral ? getBaseTypeOfLiteralType(caseType) : caseType;
-                    }
+                    const caseType = checkExpression(caseClause.expression);
                     if (!isTypeEqualityComparableTo(expressionType, caseType)) {
                         // expressionType is not comparable to caseType, try the reversed check and report errors if it fails
                         checkTypeComparableTo(caseType, expressionType, caseClause.expression, /*headMessage*/ undefined);

From 83d6abcd9eb829c9ac01376d27741228e09d1ae6 Mon Sep 17 00:00:00 2001
From: Nathan Shively-Sanders <nathansa@microsoft.com>
Date: Fri, 14 Oct 2016 08:59:00 -0700
Subject: [PATCH 4/9] Update baselines

There are more literal types in error messages because error reporting
no longer has the advantage of calls to getBaseLiteralType
---
 tests/baselines/reference/expr.errors.txt       |  8 ++++----
 .../for-inStatementsArrayErrors.errors.txt      |  4 ++--
 ...AssertionsInEqualityComparisons02.errors.txt |  4 ++--
 .../reference/switchAssignmentCompat.errors.txt |  4 ++--
 .../switchCaseCircularRefeference.errors.txt    | 10 ++++++----
 ...switchCasesExpressionTypeMismatch.errors.txt | 17 ++++++++++-------
 .../baselines/reference/symbolType9.errors.txt  | 16 ++++++++--------
 7 files changed, 34 insertions(+), 29 deletions(-)

diff --git a/tests/baselines/reference/expr.errors.txt b/tests/baselines/reference/expr.errors.txt
index 23215cac6bae2..52f6f64fef287 100644
--- a/tests/baselines/reference/expr.errors.txt
+++ b/tests/baselines/reference/expr.errors.txt
@@ -1,7 +1,7 @@
 tests/cases/compiler/expr.ts(87,5): error TS2365: Operator '==' cannot be applied to types 'number' and 'string'.
-tests/cases/compiler/expr.ts(88,5): error TS2365: Operator '==' cannot be applied to types 'number' and 'boolean'.
+tests/cases/compiler/expr.ts(88,5): error TS2365: Operator '==' cannot be applied to types 'number' and 'false'.
 tests/cases/compiler/expr.ts(94,5): error TS2365: Operator '==' cannot be applied to types 'string' and 'number'.
-tests/cases/compiler/expr.ts(95,5): error TS2365: Operator '==' cannot be applied to types 'string' and 'boolean'.
+tests/cases/compiler/expr.ts(95,5): error TS2365: Operator '==' cannot be applied to types 'string' and 'false'.
 tests/cases/compiler/expr.ts(98,5): error TS2365: Operator '==' cannot be applied to types 'string' and 'E'.
 tests/cases/compiler/expr.ts(115,5): error TS2365: Operator '==' cannot be applied to types 'E' and 'string'.
 tests/cases/compiler/expr.ts(116,5): error TS2365: Operator '==' cannot be applied to types 'E' and 'false'.
@@ -161,7 +161,7 @@ tests/cases/compiler/expr.ts(242,7): error TS2363: The right-hand side of an ari
 !!! error TS2365: Operator '==' cannot be applied to types 'number' and 'string'.
         n==b;
         ~~~~
-!!! error TS2365: Operator '==' cannot be applied to types 'number' and 'boolean'.
+!!! error TS2365: Operator '==' cannot be applied to types 'number' and 'false'.
         n==i;
         n==n;
         n==e;
@@ -172,7 +172,7 @@ tests/cases/compiler/expr.ts(242,7): error TS2363: The right-hand side of an ari
 !!! error TS2365: Operator '==' cannot be applied to types 'string' and 'number'.
         s==b;
         ~~~~
-!!! error TS2365: Operator '==' cannot be applied to types 'string' and 'boolean'.
+!!! error TS2365: Operator '==' cannot be applied to types 'string' and 'false'.
         s==i;
         s==s;
         s==e;
diff --git a/tests/baselines/reference/for-inStatementsArrayErrors.errors.txt b/tests/baselines/reference/for-inStatementsArrayErrors.errors.txt
index 6886d992bb2e5..e639d8452de21 100644
--- a/tests/baselines/reference/for-inStatementsArrayErrors.errors.txt
+++ b/tests/baselines/reference/for-inStatementsArrayErrors.errors.txt
@@ -1,6 +1,6 @@
 tests/cases/conformance/statements/for-inStatements/for-inStatementsArrayErrors.ts(5,14): error TS7015: Element implicitly has an 'any' type because index expression is not of type 'number'.
 tests/cases/conformance/statements/for-inStatements/for-inStatementsArrayErrors.ts(6,16): error TS2362: The left-hand side of an arithmetic operation must be of type 'any', 'number' or an enum type.
-tests/cases/conformance/statements/for-inStatements/for-inStatementsArrayErrors.ts(7,9): error TS2365: Operator '===' cannot be applied to types 'string' and 'number'.
+tests/cases/conformance/statements/for-inStatements/for-inStatementsArrayErrors.ts(7,9): error TS2365: Operator '===' cannot be applied to types 'string' and '1'.
 tests/cases/conformance/statements/for-inStatements/for-inStatementsArrayErrors.ts(9,16): error TS2339: Property 'unknownProperty' does not exist on type 'string'.
 tests/cases/conformance/statements/for-inStatements/for-inStatementsArrayErrors.ts(13,10): error TS2403: Subsequent variable declarations must have the same type.  Variable 'i' must be of type 'number', but here has type 'string'.
 tests/cases/conformance/statements/for-inStatements/for-inStatementsArrayErrors.ts(17,10): error TS2403: Subsequent variable declarations must have the same type.  Variable 'j' must be of type 'any', but here has type 'string'.
@@ -19,7 +19,7 @@ tests/cases/conformance/statements/for-inStatements/for-inStatementsArrayErrors.
 !!! error TS2362: The left-hand side of an arithmetic operation must be of type 'any', 'number' or an enum type.
         if (x === 1) {
             ~~~~~~~
-!!! error TS2365: Operator '===' cannot be applied to types 'string' and 'number'.
+!!! error TS2365: Operator '===' cannot be applied to types 'string' and '1'.
         }
         let a3 = x.unknownProperty;
                    ~~~~~~~~~~~~~~~
diff --git a/tests/baselines/reference/stringLiteralsAssertionsInEqualityComparisons02.errors.txt b/tests/baselines/reference/stringLiteralsAssertionsInEqualityComparisons02.errors.txt
index fd92af4e84f63..81adf58dbde90 100644
--- a/tests/baselines/reference/stringLiteralsAssertionsInEqualityComparisons02.errors.txt
+++ b/tests/baselines/reference/stringLiteralsAssertionsInEqualityComparisons02.errors.txt
@@ -1,5 +1,5 @@
 tests/cases/conformance/types/literal/stringLiteralsAssertionsInEqualityComparisons02.ts(3,9): error TS2365: Operator '===' cannot be applied to types '"foo"' and '"baz"'.
-tests/cases/conformance/types/literal/stringLiteralsAssertionsInEqualityComparisons02.ts(5,9): error TS2365: Operator '==' cannot be applied to types 'string' and 'number'.
+tests/cases/conformance/types/literal/stringLiteralsAssertionsInEqualityComparisons02.ts(5,9): error TS2365: Operator '==' cannot be applied to types '"foo"' and 'number'.
 tests/cases/conformance/types/literal/stringLiteralsAssertionsInEqualityComparisons02.ts(5,19): error TS2352: Type 'string' cannot be converted to type 'number'.
 
 
@@ -12,7 +12,7 @@ tests/cases/conformance/types/literal/stringLiteralsAssertionsInEqualityComparis
     var b = "foo" !== ("bar" as "foo");
     var c = "foo" == (<number>"bar");
             ~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2365: Operator '==' cannot be applied to types 'string' and 'number'.
+!!! error TS2365: Operator '==' cannot be applied to types '"foo"' and 'number'.
                       ~~~~~~~~~~~~~
 !!! error TS2352: Type 'string' cannot be converted to type 'number'.
     var d = "foo" === ("bar" as EnhancedString);
\ No newline at end of file
diff --git a/tests/baselines/reference/switchAssignmentCompat.errors.txt b/tests/baselines/reference/switchAssignmentCompat.errors.txt
index 747a1035b6846..46c89fa5b52d2 100644
--- a/tests/baselines/reference/switchAssignmentCompat.errors.txt
+++ b/tests/baselines/reference/switchAssignmentCompat.errors.txt
@@ -1,4 +1,4 @@
-tests/cases/compiler/switchAssignmentCompat.ts(4,10): error TS2678: Type 'typeof Foo' is not comparable to type 'number'.
+tests/cases/compiler/switchAssignmentCompat.ts(4,10): error TS2678: Type 'typeof Foo' is not comparable to type '0'.
 
 
 ==== tests/cases/compiler/switchAssignmentCompat.ts (1 errors) ====
@@ -7,6 +7,6 @@ tests/cases/compiler/switchAssignmentCompat.ts(4,10): error TS2678: Type 'typeof
     switch (0) {
         case Foo: break; // Error expected
              ~~~
-!!! error TS2678: Type 'typeof Foo' is not comparable to type 'number'.
+!!! error TS2678: Type 'typeof Foo' is not comparable to type '0'.
     }
     
\ No newline at end of file
diff --git a/tests/baselines/reference/switchCaseCircularRefeference.errors.txt b/tests/baselines/reference/switchCaseCircularRefeference.errors.txt
index bc576f8e723b8..9ee571de468ce 100644
--- a/tests/baselines/reference/switchCaseCircularRefeference.errors.txt
+++ b/tests/baselines/reference/switchCaseCircularRefeference.errors.txt
@@ -1,5 +1,6 @@
-tests/cases/compiler/switchCaseCircularRefeference.ts(5,10): error TS2678: Type '{ a: "A"; b: any; } | { a: "C"; e: any; }' is not comparable to type 'string'.
-  Type '{ a: "C"; e: any; }' is not comparable to type 'string'.
+tests/cases/compiler/switchCaseCircularRefeference.ts(5,10): error TS2678: Type '{ a: "A"; b: any; } | { a: "C"; e: any; }' is not comparable to type '"A" | "C"'.
+  Type '{ a: "C"; e: any; }' is not comparable to type '"A" | "C"'.
+    Type '{ a: "C"; e: any; }' is not comparable to type '"C"'.
 
 
 ==== tests/cases/compiler/switchCaseCircularRefeference.ts (1 errors) ====
@@ -9,8 +10,9 @@ tests/cases/compiler/switchCaseCircularRefeference.ts(5,10): error TS2678: Type
         switch (x.a) {
         case x:
              ~
-!!! error TS2678: Type '{ a: "A"; b: any; } | { a: "C"; e: any; }' is not comparable to type 'string'.
-!!! error TS2678:   Type '{ a: "C"; e: any; }' is not comparable to type 'string'.
+!!! error TS2678: Type '{ a: "A"; b: any; } | { a: "C"; e: any; }' is not comparable to type '"A" | "C"'.
+!!! error TS2678:   Type '{ a: "C"; e: any; }' is not comparable to type '"A" | "C"'.
+!!! error TS2678:     Type '{ a: "C"; e: any; }' is not comparable to type '"C"'.
             break;
         }
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/switchCasesExpressionTypeMismatch.errors.txt b/tests/baselines/reference/switchCasesExpressionTypeMismatch.errors.txt
index 26d39efef48ec..3ea12e2460f65 100644
--- a/tests/baselines/reference/switchCasesExpressionTypeMismatch.errors.txt
+++ b/tests/baselines/reference/switchCasesExpressionTypeMismatch.errors.txt
@@ -1,22 +1,25 @@
-tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(4,10): error TS2678: Type 'typeof Foo' is not comparable to type 'number'.
-tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(5,10): error TS2678: Type 'string' is not comparable to type 'number'.
-tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(7,10): error TS2678: Type 'boolean' is not comparable to type 'number'.
+tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(4,10): error TS2678: Type 'typeof Foo' is not comparable to type '0'.
+tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(5,10): error TS2678: Type '"sss"' is not comparable to type '0'.
+tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(6,10): error TS2678: Type '123' is not comparable to type '0'.
+tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(7,10): error TS2678: Type 'true' is not comparable to type '0'.
 
 
-==== tests/cases/compiler/switchCasesExpressionTypeMismatch.ts (3 errors) ====
+==== tests/cases/compiler/switchCasesExpressionTypeMismatch.ts (4 errors) ====
     class Foo { }
     
     switch (0) {
         case Foo: break;    // Error
              ~~~
-!!! error TS2678: Type 'typeof Foo' is not comparable to type 'number'.
+!!! error TS2678: Type 'typeof Foo' is not comparable to type '0'.
         case "sss": break;  // Error
              ~~~~~
-!!! error TS2678: Type 'string' is not comparable to type 'number'.
+!!! error TS2678: Type '"sss"' is not comparable to type '0'.
         case 123: break;    // No Error
+             ~~~
+!!! error TS2678: Type '123' is not comparable to type '0'.
         case true: break;   // Error
              ~~~~
-!!! error TS2678: Type 'boolean' is not comparable to type 'number'.
+!!! error TS2678: Type 'true' is not comparable to type '0'.
     }
     
     var s: any = 0;
diff --git a/tests/baselines/reference/symbolType9.errors.txt b/tests/baselines/reference/symbolType9.errors.txt
index 5506fdc6f9dac..55a766a379e80 100644
--- a/tests/baselines/reference/symbolType9.errors.txt
+++ b/tests/baselines/reference/symbolType9.errors.txt
@@ -1,7 +1,7 @@
-tests/cases/conformance/es6/Symbols/symbolType9.ts(3,1): error TS2365: Operator '==' cannot be applied to types 'symbol' and 'boolean'.
-tests/cases/conformance/es6/Symbols/symbolType9.ts(5,1): error TS2365: Operator '!=' cannot be applied to types 'number' and 'symbol'.
-tests/cases/conformance/es6/Symbols/symbolType9.ts(7,1): error TS2365: Operator '===' cannot be applied to types 'symbol' and 'number'.
-tests/cases/conformance/es6/Symbols/symbolType9.ts(9,1): error TS2365: Operator '!==' cannot be applied to types 'boolean' and 'symbol'.
+tests/cases/conformance/es6/Symbols/symbolType9.ts(3,1): error TS2365: Operator '==' cannot be applied to types 'symbol' and 'true'.
+tests/cases/conformance/es6/Symbols/symbolType9.ts(5,1): error TS2365: Operator '!=' cannot be applied to types '0' and 'symbol'.
+tests/cases/conformance/es6/Symbols/symbolType9.ts(7,1): error TS2365: Operator '===' cannot be applied to types 'symbol' and '1'.
+tests/cases/conformance/es6/Symbols/symbolType9.ts(9,1): error TS2365: Operator '!==' cannot be applied to types 'false' and 'symbol'.
 
 
 ==== tests/cases/conformance/es6/Symbols/symbolType9.ts (4 errors) ====
@@ -9,16 +9,16 @@ tests/cases/conformance/es6/Symbols/symbolType9.ts(9,1): error TS2365: Operator
     s == s;
     s == true;
     ~~~~~~~~~
-!!! error TS2365: Operator '==' cannot be applied to types 'symbol' and 'boolean'.
+!!! error TS2365: Operator '==' cannot be applied to types 'symbol' and 'true'.
     s != s;
     0 != s;
     ~~~~~~
-!!! error TS2365: Operator '!=' cannot be applied to types 'number' and 'symbol'.
+!!! error TS2365: Operator '!=' cannot be applied to types '0' and 'symbol'.
     s === s;
     s === 1;
     ~~~~~~~
-!!! error TS2365: Operator '===' cannot be applied to types 'symbol' and 'number'.
+!!! error TS2365: Operator '===' cannot be applied to types 'symbol' and '1'.
     s !== s;
     false !== s;
     ~~~~~~~~~~~
-!!! error TS2365: Operator '!==' cannot be applied to types 'boolean' and 'symbol'.
\ No newline at end of file
+!!! error TS2365: Operator '!==' cannot be applied to types 'false' and 'symbol'.
\ No newline at end of file

From ebef408dfa18061fb3ae984bbc2f0315177d756b Mon Sep 17 00:00:00 2001
From: Nathan Shively-Sanders <nathansa@microsoft.com>
Date: Mon, 31 Oct 2016 14:44:04 -0700
Subject: [PATCH 5/9] Move eitherIsNotLiteral check into switch and === checks

This improves error messages
---
 src/compiler/checker.ts                       | 22 ++++++++++++-------
 tests/baselines/reference/expr.errors.txt     |  8 +++----
 .../for-inStatementsArrayErrors.errors.txt    |  4 ++--
 ...sertionsInEqualityComparisons02.errors.txt |  4 ++--
 .../switchAssignmentCompat.errors.txt         |  4 ++--
 .../switchCaseCircularRefeference.errors.txt  | 10 ++++-----
 ...itchCasesExpressionTypeMismatch.errors.txt | 17 ++++++--------
 .../reference/symbolType9.errors.txt          | 16 +++++++-------
 8 files changed, 43 insertions(+), 42 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index d76d4e1e77018..2d05e16ef825e 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -13814,12 +13814,6 @@ namespace ts {
         }
 
         function isTypeEqualityComparableTo(source: Type, target: Type) {
-            const sourceIsLiteral = isLiteralType(source);
-            const targetIsLiteral = isLiteralType(target);
-            if (!sourceIsLiteral || !targetIsLiteral) {
-                source = sourceIsLiteral ? getBaseTypeOfLiteralType(source) : source;
-                target = targetIsLiteral ? getBaseTypeOfLiteralType(target) : target;
-            }
             return (target.flags & TypeFlags.Nullable) !== 0 || isTypeComparableTo(source, target);
         }
 
@@ -13960,6 +13954,12 @@ namespace ts {
                 case SyntaxKind.ExclamationEqualsToken:
                 case SyntaxKind.EqualsEqualsEqualsToken:
                 case SyntaxKind.ExclamationEqualsEqualsToken:
+                    const leftIsLiteral = isLiteralType(leftType);
+                    const rightIsLiteral = isLiteralType(rightType);
+                    if (!leftIsLiteral || !rightIsLiteral) {
+                        leftType = leftIsLiteral ? getBaseTypeOfLiteralType(leftType) : leftType;
+                        rightType = rightIsLiteral ? getBaseTypeOfLiteralType(rightType) : rightType;
+                    }
                     if (!isTypeEqualityComparableTo(leftType, rightType) && !isTypeEqualityComparableTo(rightType, leftType)) {
                         reportOperatorError();
                     }
@@ -16882,7 +16882,7 @@ namespace ts {
             let firstDefaultClause: CaseOrDefaultClause;
             let hasDuplicateDefaultClause = false;
 
-            const expressionType = checkExpression(node.expression);
+            let expressionType = checkExpression(node.expression);
             forEach(node.caseBlock.clauses, clause => {
                 // Grammar check for duplicate default clauses, skip if we already report duplicate default clause
                 if (clause.kind === SyntaxKind.DefaultClause && !hasDuplicateDefaultClause) {
@@ -16903,7 +16903,13 @@ namespace ts {
                     // TypeScript 1.0 spec (April 2014): 5.9
                     // In a 'switch' statement, each 'case' expression must be of a type that is comparable
                     // to or from the type of the 'switch' expression.
-                    const caseType = checkExpression(caseClause.expression);
+                    let caseType = checkExpression(caseClause.expression);
+                    const caseIsLiteral = isLiteralType(caseType);
+                    const expressionIsLiteral = isLiteralType(expressionType);
+                    if (!caseIsLiteral || !expressionIsLiteral) {
+                        caseType = caseIsLiteral ? getBaseTypeOfLiteralType(caseType) : caseType;
+                        expressionType = expressionIsLiteral ? getBaseTypeOfLiteralType(expressionType) : expressionType;
+                    }
                     if (!isTypeEqualityComparableTo(expressionType, caseType)) {
                         // expressionType is not comparable to caseType, try the reversed check and report errors if it fails
                         checkTypeComparableTo(caseType, expressionType, caseClause.expression, /*headMessage*/ undefined);
diff --git a/tests/baselines/reference/expr.errors.txt b/tests/baselines/reference/expr.errors.txt
index 52f6f64fef287..23215cac6bae2 100644
--- a/tests/baselines/reference/expr.errors.txt
+++ b/tests/baselines/reference/expr.errors.txt
@@ -1,7 +1,7 @@
 tests/cases/compiler/expr.ts(87,5): error TS2365: Operator '==' cannot be applied to types 'number' and 'string'.
-tests/cases/compiler/expr.ts(88,5): error TS2365: Operator '==' cannot be applied to types 'number' and 'false'.
+tests/cases/compiler/expr.ts(88,5): error TS2365: Operator '==' cannot be applied to types 'number' and 'boolean'.
 tests/cases/compiler/expr.ts(94,5): error TS2365: Operator '==' cannot be applied to types 'string' and 'number'.
-tests/cases/compiler/expr.ts(95,5): error TS2365: Operator '==' cannot be applied to types 'string' and 'false'.
+tests/cases/compiler/expr.ts(95,5): error TS2365: Operator '==' cannot be applied to types 'string' and 'boolean'.
 tests/cases/compiler/expr.ts(98,5): error TS2365: Operator '==' cannot be applied to types 'string' and 'E'.
 tests/cases/compiler/expr.ts(115,5): error TS2365: Operator '==' cannot be applied to types 'E' and 'string'.
 tests/cases/compiler/expr.ts(116,5): error TS2365: Operator '==' cannot be applied to types 'E' and 'false'.
@@ -161,7 +161,7 @@ tests/cases/compiler/expr.ts(242,7): error TS2363: The right-hand side of an ari
 !!! error TS2365: Operator '==' cannot be applied to types 'number' and 'string'.
         n==b;
         ~~~~
-!!! error TS2365: Operator '==' cannot be applied to types 'number' and 'false'.
+!!! error TS2365: Operator '==' cannot be applied to types 'number' and 'boolean'.
         n==i;
         n==n;
         n==e;
@@ -172,7 +172,7 @@ tests/cases/compiler/expr.ts(242,7): error TS2363: The right-hand side of an ari
 !!! error TS2365: Operator '==' cannot be applied to types 'string' and 'number'.
         s==b;
         ~~~~
-!!! error TS2365: Operator '==' cannot be applied to types 'string' and 'false'.
+!!! error TS2365: Operator '==' cannot be applied to types 'string' and 'boolean'.
         s==i;
         s==s;
         s==e;
diff --git a/tests/baselines/reference/for-inStatementsArrayErrors.errors.txt b/tests/baselines/reference/for-inStatementsArrayErrors.errors.txt
index e639d8452de21..6886d992bb2e5 100644
--- a/tests/baselines/reference/for-inStatementsArrayErrors.errors.txt
+++ b/tests/baselines/reference/for-inStatementsArrayErrors.errors.txt
@@ -1,6 +1,6 @@
 tests/cases/conformance/statements/for-inStatements/for-inStatementsArrayErrors.ts(5,14): error TS7015: Element implicitly has an 'any' type because index expression is not of type 'number'.
 tests/cases/conformance/statements/for-inStatements/for-inStatementsArrayErrors.ts(6,16): error TS2362: The left-hand side of an arithmetic operation must be of type 'any', 'number' or an enum type.
-tests/cases/conformance/statements/for-inStatements/for-inStatementsArrayErrors.ts(7,9): error TS2365: Operator '===' cannot be applied to types 'string' and '1'.
+tests/cases/conformance/statements/for-inStatements/for-inStatementsArrayErrors.ts(7,9): error TS2365: Operator '===' cannot be applied to types 'string' and 'number'.
 tests/cases/conformance/statements/for-inStatements/for-inStatementsArrayErrors.ts(9,16): error TS2339: Property 'unknownProperty' does not exist on type 'string'.
 tests/cases/conformance/statements/for-inStatements/for-inStatementsArrayErrors.ts(13,10): error TS2403: Subsequent variable declarations must have the same type.  Variable 'i' must be of type 'number', but here has type 'string'.
 tests/cases/conformance/statements/for-inStatements/for-inStatementsArrayErrors.ts(17,10): error TS2403: Subsequent variable declarations must have the same type.  Variable 'j' must be of type 'any', but here has type 'string'.
@@ -19,7 +19,7 @@ tests/cases/conformance/statements/for-inStatements/for-inStatementsArrayErrors.
 !!! error TS2362: The left-hand side of an arithmetic operation must be of type 'any', 'number' or an enum type.
         if (x === 1) {
             ~~~~~~~
-!!! error TS2365: Operator '===' cannot be applied to types 'string' and '1'.
+!!! error TS2365: Operator '===' cannot be applied to types 'string' and 'number'.
         }
         let a3 = x.unknownProperty;
                    ~~~~~~~~~~~~~~~
diff --git a/tests/baselines/reference/stringLiteralsAssertionsInEqualityComparisons02.errors.txt b/tests/baselines/reference/stringLiteralsAssertionsInEqualityComparisons02.errors.txt
index 81adf58dbde90..fd92af4e84f63 100644
--- a/tests/baselines/reference/stringLiteralsAssertionsInEqualityComparisons02.errors.txt
+++ b/tests/baselines/reference/stringLiteralsAssertionsInEqualityComparisons02.errors.txt
@@ -1,5 +1,5 @@
 tests/cases/conformance/types/literal/stringLiteralsAssertionsInEqualityComparisons02.ts(3,9): error TS2365: Operator '===' cannot be applied to types '"foo"' and '"baz"'.
-tests/cases/conformance/types/literal/stringLiteralsAssertionsInEqualityComparisons02.ts(5,9): error TS2365: Operator '==' cannot be applied to types '"foo"' and 'number'.
+tests/cases/conformance/types/literal/stringLiteralsAssertionsInEqualityComparisons02.ts(5,9): error TS2365: Operator '==' cannot be applied to types 'string' and 'number'.
 tests/cases/conformance/types/literal/stringLiteralsAssertionsInEqualityComparisons02.ts(5,19): error TS2352: Type 'string' cannot be converted to type 'number'.
 
 
@@ -12,7 +12,7 @@ tests/cases/conformance/types/literal/stringLiteralsAssertionsInEqualityComparis
     var b = "foo" !== ("bar" as "foo");
     var c = "foo" == (<number>"bar");
             ~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2365: Operator '==' cannot be applied to types '"foo"' and 'number'.
+!!! error TS2365: Operator '==' cannot be applied to types 'string' and 'number'.
                       ~~~~~~~~~~~~~
 !!! error TS2352: Type 'string' cannot be converted to type 'number'.
     var d = "foo" === ("bar" as EnhancedString);
\ No newline at end of file
diff --git a/tests/baselines/reference/switchAssignmentCompat.errors.txt b/tests/baselines/reference/switchAssignmentCompat.errors.txt
index 46c89fa5b52d2..747a1035b6846 100644
--- a/tests/baselines/reference/switchAssignmentCompat.errors.txt
+++ b/tests/baselines/reference/switchAssignmentCompat.errors.txt
@@ -1,4 +1,4 @@
-tests/cases/compiler/switchAssignmentCompat.ts(4,10): error TS2678: Type 'typeof Foo' is not comparable to type '0'.
+tests/cases/compiler/switchAssignmentCompat.ts(4,10): error TS2678: Type 'typeof Foo' is not comparable to type 'number'.
 
 
 ==== tests/cases/compiler/switchAssignmentCompat.ts (1 errors) ====
@@ -7,6 +7,6 @@ tests/cases/compiler/switchAssignmentCompat.ts(4,10): error TS2678: Type 'typeof
     switch (0) {
         case Foo: break; // Error expected
              ~~~
-!!! error TS2678: Type 'typeof Foo' is not comparable to type '0'.
+!!! error TS2678: Type 'typeof Foo' is not comparable to type 'number'.
     }
     
\ No newline at end of file
diff --git a/tests/baselines/reference/switchCaseCircularRefeference.errors.txt b/tests/baselines/reference/switchCaseCircularRefeference.errors.txt
index 9ee571de468ce..bc576f8e723b8 100644
--- a/tests/baselines/reference/switchCaseCircularRefeference.errors.txt
+++ b/tests/baselines/reference/switchCaseCircularRefeference.errors.txt
@@ -1,6 +1,5 @@
-tests/cases/compiler/switchCaseCircularRefeference.ts(5,10): error TS2678: Type '{ a: "A"; b: any; } | { a: "C"; e: any; }' is not comparable to type '"A" | "C"'.
-  Type '{ a: "C"; e: any; }' is not comparable to type '"A" | "C"'.
-    Type '{ a: "C"; e: any; }' is not comparable to type '"C"'.
+tests/cases/compiler/switchCaseCircularRefeference.ts(5,10): error TS2678: Type '{ a: "A"; b: any; } | { a: "C"; e: any; }' is not comparable to type 'string'.
+  Type '{ a: "C"; e: any; }' is not comparable to type 'string'.
 
 
 ==== tests/cases/compiler/switchCaseCircularRefeference.ts (1 errors) ====
@@ -10,9 +9,8 @@ tests/cases/compiler/switchCaseCircularRefeference.ts(5,10): error TS2678: Type
         switch (x.a) {
         case x:
              ~
-!!! error TS2678: Type '{ a: "A"; b: any; } | { a: "C"; e: any; }' is not comparable to type '"A" | "C"'.
-!!! error TS2678:   Type '{ a: "C"; e: any; }' is not comparable to type '"A" | "C"'.
-!!! error TS2678:     Type '{ a: "C"; e: any; }' is not comparable to type '"C"'.
+!!! error TS2678: Type '{ a: "A"; b: any; } | { a: "C"; e: any; }' is not comparable to type 'string'.
+!!! error TS2678:   Type '{ a: "C"; e: any; }' is not comparable to type 'string'.
             break;
         }
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/switchCasesExpressionTypeMismatch.errors.txt b/tests/baselines/reference/switchCasesExpressionTypeMismatch.errors.txt
index 3ea12e2460f65..26d39efef48ec 100644
--- a/tests/baselines/reference/switchCasesExpressionTypeMismatch.errors.txt
+++ b/tests/baselines/reference/switchCasesExpressionTypeMismatch.errors.txt
@@ -1,25 +1,22 @@
-tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(4,10): error TS2678: Type 'typeof Foo' is not comparable to type '0'.
-tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(5,10): error TS2678: Type '"sss"' is not comparable to type '0'.
-tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(6,10): error TS2678: Type '123' is not comparable to type '0'.
-tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(7,10): error TS2678: Type 'true' is not comparable to type '0'.
+tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(4,10): error TS2678: Type 'typeof Foo' is not comparable to type 'number'.
+tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(5,10): error TS2678: Type 'string' is not comparable to type 'number'.
+tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(7,10): error TS2678: Type 'boolean' is not comparable to type 'number'.
 
 
-==== tests/cases/compiler/switchCasesExpressionTypeMismatch.ts (4 errors) ====
+==== tests/cases/compiler/switchCasesExpressionTypeMismatch.ts (3 errors) ====
     class Foo { }
     
     switch (0) {
         case Foo: break;    // Error
              ~~~
-!!! error TS2678: Type 'typeof Foo' is not comparable to type '0'.
+!!! error TS2678: Type 'typeof Foo' is not comparable to type 'number'.
         case "sss": break;  // Error
              ~~~~~
-!!! error TS2678: Type '"sss"' is not comparable to type '0'.
+!!! error TS2678: Type 'string' is not comparable to type 'number'.
         case 123: break;    // No Error
-             ~~~
-!!! error TS2678: Type '123' is not comparable to type '0'.
         case true: break;   // Error
              ~~~~
-!!! error TS2678: Type 'true' is not comparable to type '0'.
+!!! error TS2678: Type 'boolean' is not comparable to type 'number'.
     }
     
     var s: any = 0;
diff --git a/tests/baselines/reference/symbolType9.errors.txt b/tests/baselines/reference/symbolType9.errors.txt
index 55a766a379e80..5506fdc6f9dac 100644
--- a/tests/baselines/reference/symbolType9.errors.txt
+++ b/tests/baselines/reference/symbolType9.errors.txt
@@ -1,7 +1,7 @@
-tests/cases/conformance/es6/Symbols/symbolType9.ts(3,1): error TS2365: Operator '==' cannot be applied to types 'symbol' and 'true'.
-tests/cases/conformance/es6/Symbols/symbolType9.ts(5,1): error TS2365: Operator '!=' cannot be applied to types '0' and 'symbol'.
-tests/cases/conformance/es6/Symbols/symbolType9.ts(7,1): error TS2365: Operator '===' cannot be applied to types 'symbol' and '1'.
-tests/cases/conformance/es6/Symbols/symbolType9.ts(9,1): error TS2365: Operator '!==' cannot be applied to types 'false' and 'symbol'.
+tests/cases/conformance/es6/Symbols/symbolType9.ts(3,1): error TS2365: Operator '==' cannot be applied to types 'symbol' and 'boolean'.
+tests/cases/conformance/es6/Symbols/symbolType9.ts(5,1): error TS2365: Operator '!=' cannot be applied to types 'number' and 'symbol'.
+tests/cases/conformance/es6/Symbols/symbolType9.ts(7,1): error TS2365: Operator '===' cannot be applied to types 'symbol' and 'number'.
+tests/cases/conformance/es6/Symbols/symbolType9.ts(9,1): error TS2365: Operator '!==' cannot be applied to types 'boolean' and 'symbol'.
 
 
 ==== tests/cases/conformance/es6/Symbols/symbolType9.ts (4 errors) ====
@@ -9,16 +9,16 @@ tests/cases/conformance/es6/Symbols/symbolType9.ts(9,1): error TS2365: Operator
     s == s;
     s == true;
     ~~~~~~~~~
-!!! error TS2365: Operator '==' cannot be applied to types 'symbol' and 'true'.
+!!! error TS2365: Operator '==' cannot be applied to types 'symbol' and 'boolean'.
     s != s;
     0 != s;
     ~~~~~~
-!!! error TS2365: Operator '!=' cannot be applied to types '0' and 'symbol'.
+!!! error TS2365: Operator '!=' cannot be applied to types 'number' and 'symbol'.
     s === s;
     s === 1;
     ~~~~~~~
-!!! error TS2365: Operator '===' cannot be applied to types 'symbol' and '1'.
+!!! error TS2365: Operator '===' cannot be applied to types 'symbol' and 'number'.
     s !== s;
     false !== s;
     ~~~~~~~~~~~
-!!! error TS2365: Operator '!==' cannot be applied to types 'false' and 'symbol'.
\ No newline at end of file
+!!! error TS2365: Operator '!==' cannot be applied to types 'boolean' and 'symbol'.
\ No newline at end of file

From d7f5fc8fcf1c083029588217303324a145c20650 Mon Sep 17 00:00:00 2001
From: Nathan Shively-Sanders <nathansa@microsoft.com>
Date: Tue, 1 Nov 2016 09:09:40 -0700
Subject: [PATCH 6/9] Get literal type only once

---
 src/compiler/checker.ts | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 2d05e16ef825e..326d84278be24 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -16882,7 +16882,8 @@ namespace ts {
             let firstDefaultClause: CaseOrDefaultClause;
             let hasDuplicateDefaultClause = false;
 
-            let expressionType = checkExpression(node.expression);
+            const expressionType = checkExpression(node.expression);
+            const expressionIsLiteral = isLiteralType(expressionType);
             forEach(node.caseBlock.clauses, clause => {
                 // Grammar check for duplicate default clauses, skip if we already report duplicate default clause
                 if (clause.kind === SyntaxKind.DefaultClause && !hasDuplicateDefaultClause) {
@@ -16905,14 +16906,14 @@ namespace ts {
                     // to or from the type of the 'switch' expression.
                     let caseType = checkExpression(caseClause.expression);
                     const caseIsLiteral = isLiteralType(caseType);
-                    const expressionIsLiteral = isLiteralType(expressionType);
+                    let literalExpressionType = expressionType;
                     if (!caseIsLiteral || !expressionIsLiteral) {
                         caseType = caseIsLiteral ? getBaseTypeOfLiteralType(caseType) : caseType;
-                        expressionType = expressionIsLiteral ? getBaseTypeOfLiteralType(expressionType) : expressionType;
+                        literalExpressionType = getBaseTypeOfLiteralType(expressionType);
                     }
-                    if (!isTypeEqualityComparableTo(expressionType, caseType)) {
+                    if (!isTypeEqualityComparableTo(literalExpressionType, caseType)) {
                         // expressionType is not comparable to caseType, try the reversed check and report errors if it fails
-                        checkTypeComparableTo(caseType, expressionType, caseClause.expression, /*headMessage*/ undefined);
+                        checkTypeComparableTo(caseType, literalExpressionType, caseClause.expression, /*headMessage*/ undefined);
                     }
                 }
                 forEach(clause.statements, checkSourceElement);

From 357d58b4f1ea650e8b261a45aef66febaaadc55e Mon Sep 17 00:00:00 2001
From: Nathan Shively-Sanders <nathansa@microsoft.com>
Date: Tue, 1 Nov 2016 09:10:39 -0700
Subject: [PATCH 7/9] Update baselines

---
 ...witchCasesExpressionTypeMismatch.errors.txt | 18 +++++++++++-------
 .../switchCasesExpressionTypeMismatch.js       |  7 ++++---
 2 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/tests/baselines/reference/switchCasesExpressionTypeMismatch.errors.txt b/tests/baselines/reference/switchCasesExpressionTypeMismatch.errors.txt
index 26d39efef48ec..7a5fd12182e4e 100644
--- a/tests/baselines/reference/switchCasesExpressionTypeMismatch.errors.txt
+++ b/tests/baselines/reference/switchCasesExpressionTypeMismatch.errors.txt
@@ -1,9 +1,10 @@
 tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(4,10): error TS2678: Type 'typeof Foo' is not comparable to type 'number'.
-tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(5,10): error TS2678: Type 'string' is not comparable to type 'number'.
-tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(7,10): error TS2678: Type 'boolean' is not comparable to type 'number'.
+tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(5,10): error TS2678: Type '"sss"' is not comparable to type '0'.
+tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(6,10): error TS2678: Type '123' is not comparable to type '0'.
+tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(7,10): error TS2678: Type 'true' is not comparable to type '0'.
 
 
-==== tests/cases/compiler/switchCasesExpressionTypeMismatch.ts (3 errors) ====
+==== tests/cases/compiler/switchCasesExpressionTypeMismatch.ts (4 errors) ====
     class Foo { }
     
     switch (0) {
@@ -12,11 +13,13 @@ tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(7,10): error TS2678: T
 !!! error TS2678: Type 'typeof Foo' is not comparable to type 'number'.
         case "sss": break;  // Error
              ~~~~~
-!!! error TS2678: Type 'string' is not comparable to type 'number'.
-        case 123: break;    // No Error
+!!! error TS2678: Type '"sss"' is not comparable to type '0'.
+        case 123: break;    // Error
+             ~~~
+!!! error TS2678: Type '123' is not comparable to type '0'.
         case true: break;   // Error
              ~~~~
-!!! error TS2678: Type 'boolean' is not comparable to type 'number'.
+!!! error TS2678: Type 'true' is not comparable to type '0'.
     }
     
     var s: any = 0;
@@ -27,4 +30,5 @@ tests/cases/compiler/switchCasesExpressionTypeMismatch.ts(7,10): error TS2678: T
         case "sss": break;
         case 123: break;
         case true: break;
-    }
\ No newline at end of file
+    }
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/switchCasesExpressionTypeMismatch.js b/tests/baselines/reference/switchCasesExpressionTypeMismatch.js
index ba929691d2536..43a4322457938 100644
--- a/tests/baselines/reference/switchCasesExpressionTypeMismatch.js
+++ b/tests/baselines/reference/switchCasesExpressionTypeMismatch.js
@@ -4,7 +4,7 @@ class Foo { }
 switch (0) {
     case Foo: break;    // Error
     case "sss": break;  // Error
-    case 123: break;    // No Error
+    case 123: break;    // Error
     case true: break;   // Error
 }
 
@@ -16,7 +16,8 @@ switch (s) {
     case "sss": break;
     case 123: break;
     case true: break;
-}
+}
+
 
 //// [switchCasesExpressionTypeMismatch.js]
 var Foo = (function () {
@@ -27,7 +28,7 @@ var Foo = (function () {
 switch (0) {
     case Foo: break; // Error
     case "sss": break; // Error
-    case 123: break; // No Error
+    case 123: break; // Error
     case true: break; // Error
 }
 var s = 0;

From d58a13f6a1c8020e9ab8d88355300e1eb81b5134 Mon Sep 17 00:00:00 2001
From: Nathan Shively-Sanders <nathansa@microsoft.com>
Date: Tue, 1 Nov 2016 10:07:30 -0700
Subject: [PATCH 8/9] Add missed test update

---
 tests/cases/compiler/switchCasesExpressionTypeMismatch.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tests/cases/compiler/switchCasesExpressionTypeMismatch.ts b/tests/cases/compiler/switchCasesExpressionTypeMismatch.ts
index 4de01ebba175c..ee547705b84d2 100644
--- a/tests/cases/compiler/switchCasesExpressionTypeMismatch.ts
+++ b/tests/cases/compiler/switchCasesExpressionTypeMismatch.ts
@@ -3,7 +3,7 @@ class Foo { }
 switch (0) {
     case Foo: break;    // Error
     case "sss": break;  // Error
-    case 123: break;    // No Error
+    case 123: break;    // Error
     case true: break;   // Error
 }
 
@@ -15,4 +15,4 @@ switch (s) {
     case "sss": break;
     case 123: break;
     case true: break;
-}
\ No newline at end of file
+}

From 1866d0580c4801e3d4284e5952026de680643945 Mon Sep 17 00:00:00 2001
From: Nathan Shively-Sanders <nathansa@microsoft.com>
Date: Mon, 7 Nov 2016 11:16:54 -0800
Subject: [PATCH 9/9] Rename variable in checkSwitchStatement per PR

---
 src/compiler/checker.ts | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 326d84278be24..38d3a97a2874d 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -16906,14 +16906,14 @@ namespace ts {
                     // to or from the type of the 'switch' expression.
                     let caseType = checkExpression(caseClause.expression);
                     const caseIsLiteral = isLiteralType(caseType);
-                    let literalExpressionType = expressionType;
+                    let comparedExpressionType = expressionType;
                     if (!caseIsLiteral || !expressionIsLiteral) {
                         caseType = caseIsLiteral ? getBaseTypeOfLiteralType(caseType) : caseType;
-                        literalExpressionType = getBaseTypeOfLiteralType(expressionType);
+                        comparedExpressionType = getBaseTypeOfLiteralType(expressionType);
                     }
-                    if (!isTypeEqualityComparableTo(literalExpressionType, caseType)) {
+                    if (!isTypeEqualityComparableTo(comparedExpressionType, caseType)) {
                         // expressionType is not comparable to caseType, try the reversed check and report errors if it fails
-                        checkTypeComparableTo(caseType, literalExpressionType, caseClause.expression, /*headMessage*/ undefined);
+                        checkTypeComparableTo(caseType, comparedExpressionType, caseClause.expression, /*headMessage*/ undefined);
                     }
                 }
                 forEach(clause.statements, checkSourceElement);