From fc08ff5a36cd48a7b619f8c37dd42e3fa89389af Mon Sep 17 00:00:00 2001
From: Jack Williams <jw@jackw.io>
Date: Thu, 1 Mar 2018 03:07:53 +0000
Subject: [PATCH 1/3] Check for symbol types in template expressions

---
 src/compiler/checker.ts                       |  4 ++-
 .../noImplicitSymbolToString.errors.txt       | 21 +++++++++++++++
 .../reference/noImplicitSymbolToString.js     | 18 +++++++++++++
 .../noImplicitSymbolToString.symbols          | 21 +++++++++++++++
 .../reference/noImplicitSymbolToString.types  | 26 +++++++++++++++++++
 .../compiler/noImplicitSymbolToString.ts      |  8 ++++++
 6 files changed, 97 insertions(+), 1 deletion(-)
 create mode 100644 tests/baselines/reference/noImplicitSymbolToString.errors.txt
 create mode 100644 tests/baselines/reference/noImplicitSymbolToString.js
 create mode 100644 tests/baselines/reference/noImplicitSymbolToString.symbols
 create mode 100644 tests/baselines/reference/noImplicitSymbolToString.types
 create mode 100644 tests/cases/compiler/noImplicitSymbolToString.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 9579ba80d0f..19e5e2a880c 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -19361,7 +19361,9 @@ namespace ts {
             // A place where we actually *are* concerned with the expressions' types are
             // in tagged templates.
             forEach(node.templateSpans, templateSpan => {
-                checkExpression(templateSpan.expression);
+                if (maybeTypeOfKind(checkExpression(templateSpan.expression), TypeFlags.ESSymbolLike)) {
+                    error(templateSpan.expression, Diagnostics.Type_0_cannot_be_converted_to_type_1, typeToString(esSymbolType), typeToString(stringType));
+                }
             });
 
             return stringType;
diff --git a/tests/baselines/reference/noImplicitSymbolToString.errors.txt b/tests/baselines/reference/noImplicitSymbolToString.errors.txt
new file mode 100644
index 00000000000..43f5bb88864
--- /dev/null
+++ b/tests/baselines/reference/noImplicitSymbolToString.errors.txt
@@ -0,0 +1,21 @@
+tests/cases/compiler/noImplicitSymbolToString.ts(6,30): error TS2352: Type 'symbol' cannot be converted to type 'string'.
+tests/cases/compiler/noImplicitSymbolToString.ts(7,30): error TS2469: The '+' operator cannot be applied to type 'symbol'.
+tests/cases/compiler/noImplicitSymbolToString.ts(8,8): error TS2469: The '+=' operator cannot be applied to type 'symbol'.
+
+
+==== tests/cases/compiler/noImplicitSymbolToString.ts (3 errors) ====
+    // Fix #19666
+    
+    let symbol!: symbol;
+    let str = "hello ";
+    
+    const templateStr = `hello ${symbol}`;
+                                 ~~~~~~
+!!! error TS2352: Type 'symbol' cannot be converted to type 'string'.
+    const appendStr = "hello " + symbol;
+                                 ~~~~~~
+!!! error TS2469: The '+' operator cannot be applied to type 'symbol'.
+    str += symbol;
+           ~~~~~~
+!!! error TS2469: The '+=' operator cannot be applied to type 'symbol'.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/noImplicitSymbolToString.js b/tests/baselines/reference/noImplicitSymbolToString.js
new file mode 100644
index 00000000000..c7e62c7a86e
--- /dev/null
+++ b/tests/baselines/reference/noImplicitSymbolToString.js
@@ -0,0 +1,18 @@
+//// [noImplicitSymbolToString.ts]
+// Fix #19666
+
+let symbol!: symbol;
+let str = "hello ";
+
+const templateStr = `hello ${symbol}`;
+const appendStr = "hello " + symbol;
+str += symbol;
+
+
+//// [noImplicitSymbolToString.js]
+// Fix #19666
+var symbol;
+var str = "hello ";
+var templateStr = "hello " + symbol;
+var appendStr = "hello " + symbol;
+str += symbol;
diff --git a/tests/baselines/reference/noImplicitSymbolToString.symbols b/tests/baselines/reference/noImplicitSymbolToString.symbols
new file mode 100644
index 00000000000..a043aecefb1
--- /dev/null
+++ b/tests/baselines/reference/noImplicitSymbolToString.symbols
@@ -0,0 +1,21 @@
+=== tests/cases/compiler/noImplicitSymbolToString.ts ===
+// Fix #19666
+
+let symbol!: symbol;
+>symbol : Symbol(symbol, Decl(noImplicitSymbolToString.ts, 2, 3))
+
+let str = "hello ";
+>str : Symbol(str, Decl(noImplicitSymbolToString.ts, 3, 3))
+
+const templateStr = `hello ${symbol}`;
+>templateStr : Symbol(templateStr, Decl(noImplicitSymbolToString.ts, 5, 5))
+>symbol : Symbol(symbol, Decl(noImplicitSymbolToString.ts, 2, 3))
+
+const appendStr = "hello " + symbol;
+>appendStr : Symbol(appendStr, Decl(noImplicitSymbolToString.ts, 6, 5))
+>symbol : Symbol(symbol, Decl(noImplicitSymbolToString.ts, 2, 3))
+
+str += symbol;
+>str : Symbol(str, Decl(noImplicitSymbolToString.ts, 3, 3))
+>symbol : Symbol(symbol, Decl(noImplicitSymbolToString.ts, 2, 3))
+
diff --git a/tests/baselines/reference/noImplicitSymbolToString.types b/tests/baselines/reference/noImplicitSymbolToString.types
new file mode 100644
index 00000000000..45a69c5e950
--- /dev/null
+++ b/tests/baselines/reference/noImplicitSymbolToString.types
@@ -0,0 +1,26 @@
+=== tests/cases/compiler/noImplicitSymbolToString.ts ===
+// Fix #19666
+
+let symbol!: symbol;
+>symbol : symbol
+
+let str = "hello ";
+>str : string
+>"hello " : "hello "
+
+const templateStr = `hello ${symbol}`;
+>templateStr : string
+>`hello ${symbol}` : string
+>symbol : symbol
+
+const appendStr = "hello " + symbol;
+>appendStr : string
+>"hello " + symbol : string
+>"hello " : "hello "
+>symbol : symbol
+
+str += symbol;
+>str += symbol : string
+>str : string
+>symbol : symbol
+
diff --git a/tests/cases/compiler/noImplicitSymbolToString.ts b/tests/cases/compiler/noImplicitSymbolToString.ts
new file mode 100644
index 00000000000..5340e2cd972
--- /dev/null
+++ b/tests/cases/compiler/noImplicitSymbolToString.ts
@@ -0,0 +1,8 @@
+// Fix #19666
+
+let symbol!: symbol;
+let str = "hello ";
+
+const templateStr = `hello ${symbol}`;
+const appendStr = "hello " + symbol;
+str += symbol;

From 4e5c7be228ea95352279d46e5c4566fe460644ff Mon Sep 17 00:00:00 2001
From: Jack Williams <jw@jackw.io>
Date: Tue, 6 Mar 2018 10:46:16 +0000
Subject: [PATCH 2/3] Add test case for taggedTemplate with symbol param and
 number return

---
 ...ggedTemplateStringWithSymbolExpression01.js | 17 +++++++++++++++++
 ...emplateStringWithSymbolExpression01.symbols | 16 ++++++++++++++++
 ...dTemplateStringWithSymbolExpression01.types | 18 ++++++++++++++++++
 ...ggedTemplateStringWithSymbolExpression01.ts |  6 ++++++
 4 files changed, 57 insertions(+)
 create mode 100644 tests/baselines/reference/taggedTemplateStringWithSymbolExpression01.js
 create mode 100644 tests/baselines/reference/taggedTemplateStringWithSymbolExpression01.symbols
 create mode 100644 tests/baselines/reference/taggedTemplateStringWithSymbolExpression01.types
 create mode 100644 tests/cases/compiler/taggedTemplateStringWithSymbolExpression01.ts

diff --git a/tests/baselines/reference/taggedTemplateStringWithSymbolExpression01.js b/tests/baselines/reference/taggedTemplateStringWithSymbolExpression01.js
new file mode 100644
index 00000000000..4f02e7644f7
--- /dev/null
+++ b/tests/baselines/reference/taggedTemplateStringWithSymbolExpression01.js
@@ -0,0 +1,17 @@
+//// [taggedTemplateStringWithSymbolExpression01.ts]
+// taggedTemplateStringWithSymbolExpression01.ts
+
+declare function foo(template: any, val: symbol): number;
+let x!: symbol;
+
+let result: number = foo`${x}`;
+
+
+//// [taggedTemplateStringWithSymbolExpression01.js]
+// taggedTemplateStringWithSymbolExpression01.ts
+var __makeTemplateObject = (this && this.__makeTemplateObject) || function (cooked, raw) {
+    if (Object.defineProperty) { Object.defineProperty(cooked, "raw", { value: raw }); } else { cooked.raw = raw; }
+    return cooked;
+};
+var x;
+var result = foo(__makeTemplateObject(["", ""], ["", ""]), x);
diff --git a/tests/baselines/reference/taggedTemplateStringWithSymbolExpression01.symbols b/tests/baselines/reference/taggedTemplateStringWithSymbolExpression01.symbols
new file mode 100644
index 00000000000..743d31193d4
--- /dev/null
+++ b/tests/baselines/reference/taggedTemplateStringWithSymbolExpression01.symbols
@@ -0,0 +1,16 @@
+=== tests/cases/compiler/taggedTemplateStringWithSymbolExpression01.ts ===
+// taggedTemplateStringWithSymbolExpression01.ts
+
+declare function foo(template: any, val: symbol): number;
+>foo : Symbol(foo, Decl(taggedTemplateStringWithSymbolExpression01.ts, 0, 0))
+>template : Symbol(template, Decl(taggedTemplateStringWithSymbolExpression01.ts, 2, 21))
+>val : Symbol(val, Decl(taggedTemplateStringWithSymbolExpression01.ts, 2, 35))
+
+let x!: symbol;
+>x : Symbol(x, Decl(taggedTemplateStringWithSymbolExpression01.ts, 3, 3))
+
+let result: number = foo`${x}`;
+>result : Symbol(result, Decl(taggedTemplateStringWithSymbolExpression01.ts, 5, 3))
+>foo : Symbol(foo, Decl(taggedTemplateStringWithSymbolExpression01.ts, 0, 0))
+>x : Symbol(x, Decl(taggedTemplateStringWithSymbolExpression01.ts, 3, 3))
+
diff --git a/tests/baselines/reference/taggedTemplateStringWithSymbolExpression01.types b/tests/baselines/reference/taggedTemplateStringWithSymbolExpression01.types
new file mode 100644
index 00000000000..f1a16a7f8ef
--- /dev/null
+++ b/tests/baselines/reference/taggedTemplateStringWithSymbolExpression01.types
@@ -0,0 +1,18 @@
+=== tests/cases/compiler/taggedTemplateStringWithSymbolExpression01.ts ===
+// taggedTemplateStringWithSymbolExpression01.ts
+
+declare function foo(template: any, val: symbol): number;
+>foo : (template: any, val: symbol) => number
+>template : any
+>val : symbol
+
+let x!: symbol;
+>x : symbol
+
+let result: number = foo`${x}`;
+>result : number
+>foo`${x}` : number
+>foo : (template: any, val: symbol) => number
+>`${x}` : string
+>x : symbol
+
diff --git a/tests/cases/compiler/taggedTemplateStringWithSymbolExpression01.ts b/tests/cases/compiler/taggedTemplateStringWithSymbolExpression01.ts
new file mode 100644
index 00000000000..0cbf3c00e38
--- /dev/null
+++ b/tests/cases/compiler/taggedTemplateStringWithSymbolExpression01.ts
@@ -0,0 +1,6 @@
+// taggedTemplateStringWithSymbolExpression01.ts
+
+declare function foo(template: any, val: symbol): number;
+let x!: symbol;
+
+let result: number = foo`${x}`;

From 5338500c05605f19c6295c8451f1918a638a6282 Mon Sep 17 00:00:00 2001
From: Jack Williams <jw@jackw.io>
Date: Tue, 6 Mar 2018 10:46:43 +0000
Subject: [PATCH 3/3] Update symbol template test case with errors to include
 union types

---
 .../reference/noImplicitSymbolToString.errors.txt   | 13 ++++++++++++-
 .../baselines/reference/noImplicitSymbolToString.js |  8 ++++++++
 .../reference/noImplicitSymbolToString.symbols      | 11 +++++++++++
 .../reference/noImplicitSymbolToString.types        | 12 ++++++++++++
 tests/cases/compiler/noImplicitSymbolToString.ts    |  5 +++++
 5 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/tests/baselines/reference/noImplicitSymbolToString.errors.txt b/tests/baselines/reference/noImplicitSymbolToString.errors.txt
index 43f5bb88864..6dae5c5d76f 100644
--- a/tests/baselines/reference/noImplicitSymbolToString.errors.txt
+++ b/tests/baselines/reference/noImplicitSymbolToString.errors.txt
@@ -1,9 +1,11 @@
 tests/cases/compiler/noImplicitSymbolToString.ts(6,30): error TS2352: Type 'symbol' cannot be converted to type 'string'.
 tests/cases/compiler/noImplicitSymbolToString.ts(7,30): error TS2469: The '+' operator cannot be applied to type 'symbol'.
 tests/cases/compiler/noImplicitSymbolToString.ts(8,8): error TS2469: The '+=' operator cannot be applied to type 'symbol'.
+tests/cases/compiler/noImplicitSymbolToString.ts(13,47): error TS2352: Type 'symbol' cannot be converted to type 'string'.
+tests/cases/compiler/noImplicitSymbolToString.ts(13,90): error TS2352: Type 'symbol' cannot be converted to type 'string'.
 
 
-==== tests/cases/compiler/noImplicitSymbolToString.ts (3 errors) ====
+==== tests/cases/compiler/noImplicitSymbolToString.ts (5 errors) ====
     // Fix #19666
     
     let symbol!: symbol;
@@ -18,4 +20,13 @@ tests/cases/compiler/noImplicitSymbolToString.ts(8,8): error TS2469: The '+=' op
     str += symbol;
            ~~~~~~
 !!! error TS2469: The '+=' operator cannot be applied to type 'symbol'.
+    
+    let symbolUnionNumber!: symbol | number;
+    let symbolUnionString!: symbol | string;
+    
+    const templateStrUnion = `union with number ${symbolUnionNumber} and union with string ${symbolUnionString}`;
+                                                  ~~~~~~~~~~~~~~~~~
+!!! error TS2352: Type 'symbol' cannot be converted to type 'string'.
+                                                                                             ~~~~~~~~~~~~~~~~~
+!!! error TS2352: Type 'symbol' cannot be converted to type 'string'.
     
\ No newline at end of file
diff --git a/tests/baselines/reference/noImplicitSymbolToString.js b/tests/baselines/reference/noImplicitSymbolToString.js
index c7e62c7a86e..836d5abe8a9 100644
--- a/tests/baselines/reference/noImplicitSymbolToString.js
+++ b/tests/baselines/reference/noImplicitSymbolToString.js
@@ -7,6 +7,11 @@ let str = "hello ";
 const templateStr = `hello ${symbol}`;
 const appendStr = "hello " + symbol;
 str += symbol;
+
+let symbolUnionNumber!: symbol | number;
+let symbolUnionString!: symbol | string;
+
+const templateStrUnion = `union with number ${symbolUnionNumber} and union with string ${symbolUnionString}`;
 
 
 //// [noImplicitSymbolToString.js]
@@ -16,3 +21,6 @@ var str = "hello ";
 var templateStr = "hello " + symbol;
 var appendStr = "hello " + symbol;
 str += symbol;
+var symbolUnionNumber;
+var symbolUnionString;
+var templateStrUnion = "union with number " + symbolUnionNumber + " and union with string " + symbolUnionString;
diff --git a/tests/baselines/reference/noImplicitSymbolToString.symbols b/tests/baselines/reference/noImplicitSymbolToString.symbols
index a043aecefb1..b2a08e151ab 100644
--- a/tests/baselines/reference/noImplicitSymbolToString.symbols
+++ b/tests/baselines/reference/noImplicitSymbolToString.symbols
@@ -19,3 +19,14 @@ str += symbol;
 >str : Symbol(str, Decl(noImplicitSymbolToString.ts, 3, 3))
 >symbol : Symbol(symbol, Decl(noImplicitSymbolToString.ts, 2, 3))
 
+let symbolUnionNumber!: symbol | number;
+>symbolUnionNumber : Symbol(symbolUnionNumber, Decl(noImplicitSymbolToString.ts, 9, 3))
+
+let symbolUnionString!: symbol | string;
+>symbolUnionString : Symbol(symbolUnionString, Decl(noImplicitSymbolToString.ts, 10, 3))
+
+const templateStrUnion = `union with number ${symbolUnionNumber} and union with string ${symbolUnionString}`;
+>templateStrUnion : Symbol(templateStrUnion, Decl(noImplicitSymbolToString.ts, 12, 5))
+>symbolUnionNumber : Symbol(symbolUnionNumber, Decl(noImplicitSymbolToString.ts, 9, 3))
+>symbolUnionString : Symbol(symbolUnionString, Decl(noImplicitSymbolToString.ts, 10, 3))
+
diff --git a/tests/baselines/reference/noImplicitSymbolToString.types b/tests/baselines/reference/noImplicitSymbolToString.types
index 45a69c5e950..c21c0e07bfd 100644
--- a/tests/baselines/reference/noImplicitSymbolToString.types
+++ b/tests/baselines/reference/noImplicitSymbolToString.types
@@ -24,3 +24,15 @@ str += symbol;
 >str : string
 >symbol : symbol
 
+let symbolUnionNumber!: symbol | number;
+>symbolUnionNumber : number | symbol
+
+let symbolUnionString!: symbol | string;
+>symbolUnionString : string | symbol
+
+const templateStrUnion = `union with number ${symbolUnionNumber} and union with string ${symbolUnionString}`;
+>templateStrUnion : string
+>`union with number ${symbolUnionNumber} and union with string ${symbolUnionString}` : string
+>symbolUnionNumber : number | symbol
+>symbolUnionString : string | symbol
+
diff --git a/tests/cases/compiler/noImplicitSymbolToString.ts b/tests/cases/compiler/noImplicitSymbolToString.ts
index 5340e2cd972..16690d6d845 100644
--- a/tests/cases/compiler/noImplicitSymbolToString.ts
+++ b/tests/cases/compiler/noImplicitSymbolToString.ts
@@ -6,3 +6,8 @@ let str = "hello ";
 const templateStr = `hello ${symbol}`;
 const appendStr = "hello " + symbol;
 str += symbol;
+
+let symbolUnionNumber!: symbol | number;
+let symbolUnionString!: symbol | string;
+
+const templateStrUnion = `union with number ${symbolUnionNumber} and union with string ${symbolUnionString}`;