fix: adjust block location to include a following semicolon (#229)

Fixes decaffeinate/decaffeinate#1099

Due to some complicated issues in the CoffeeScript lexer, the outdent token for
blocks can sometimes end up earlier than the semicolon ending the block. This
means that the block position ends before the semicolon, so decaffeinate ends up
making some wrong decisions because it thinks the semicolon is after the block.
I tried updating the CoffeeScript lexer to handle this but that broke other
things, so as sort of a hack, I'm just updating fixLocations to handle this
case.

Also update `yarn.lock` after running `yarn`.

Author: alangpierce

src/util/fixLocations.ts

@@ -133,6 +133,24 @@ export default function fixLocations(context: ParseContext, node: Base) {
         lastChild.locationData
       );
     }
+    // Blocks can sometimes end one index before their terminating semicolon
+    // when really they should end exactly at that semicolon.
+    let blockEnd = linesAndColumns.indexForLocation({
+      line: node.locationData.last_line,
+      column: node.locationData.last_column,
+    });
+    if (blockEnd === null) {
+      throw new Error('Expected to find index for block end.');
+    }
+    if (source[blockEnd + 1] === ';') {
+      blockEnd++;
+      let loc = linesAndColumns.locationForIndex(blockEnd);
+      if (loc === null) {
+        throw new Error('Expected to find location for block end.');
+      }
+      node.locationData.last_line = loc.line;
+      node.locationData.last_column = loc.column;
+    }
   }
 
   if (node instanceof If) {

test/examples/conditional-ending-in-semicolon/input.coffee

@@ -0,0 +1,2 @@
+x = if a
+  ;

test/examples/conditional-ending-in-semicolon/output.json

@@ -0,0 +1,68 @@
+{
+  "body": {
+    "column": 1,
+    "inline": false,
+    "line": 1,
+    "range": [
+      0,
+      12
+    ],
+    "raw": "x = if a\n  ;",
+    "statements": [
+      {
+        "assignee": {
+          "column": 1,
+          "data": "x",
+          "line": 1,
+          "range": [
+            0,
+            1
+          ],
+          "raw": "x",
+          "type": "Identifier"
+        },
+        "column": 1,
+        "expression": {
+          "alternate": null,
+          "column": 5,
+          "condition": {
+            "column": 8,
+            "data": "a",
+            "line": 1,
+            "range": [
+              7,
+              8
+            ],
+            "raw": "a",
+            "type": "Identifier"
+          },
+          "consequent": null,
+          "isUnless": false,
+          "line": 1,
+          "range": [
+            4,
+            12
+          ],
+          "raw": "if a\n  ;",
+          "type": "Conditional"
+        },
+        "line": 1,
+        "range": [
+          0,
+          12
+        ],
+        "raw": "x = if a\n  ;",
+        "type": "AssignOp"
+      }
+    ],
+    "type": "Block"
+  },
+  "column": 1,
+  "line": 1,
+  "range": [
+    0,
+    13
+  ],
+  "raw": "x = if a\n  ;\n",
+  "type": "Program"
+}

test/examples/function-ending-in-semicolon/input.coffee

@@ -0,0 +1,2 @@
+->
+  ;

test/examples/function-ending-in-semicolon/output.json

@@ -0,0 +1,36 @@
+{
+  "body": {
+    "column": 1,
+    "inline": false,
+    "line": 1,
+    "range": [
+      0,
+      6
+    ],
+    "raw": "->\n  ;",
+    "statements": [
+      {
+        "body": null,
+        "column": 1,
+        "line": 1,
+        "parameters": [
+        ],
+        "range": [
+          0,
+          6
+        ],
+        "raw": "->\n  ;",
+        "type": "Function"
+      }
+    ],
+    "type": "Block"
+  },
+  "column": 1,
+  "line": 1,
+  "range": [
+    0,
+    7
+  ],
+  "raw": "->\n  ;\n",
+  "type": "Program"
+}

yarn.lock

@@ -962,7 +962,7 @@ eslint-scope@^3.7.1:
     esrecurse "^4.1.0"
     estraverse "^4.1.1"
 
-eslint@4.1.0:
+eslint@^4.1.0:
   version "4.1.0"
   resolved "https://registry.npmjs.org/eslint/-/eslint-4.1.0.tgz#bbb55a28220ee08b69da9554d45a6b2ebfd7d913"
   dependencies: