Source Map includes mapping for line ending characters

TypeScript Version: Version 3.8.0-dev.20191023

Search Terms:

source map, source map new line

Code

tsc --inlineSourceMap test.ts

test.ts

console.log('hello');
console.log('world');

test.js

console.log('hello');
console.log('world');
//# sourceMappingURL=data:application/json;base64,eyJ2ZXJzaW9uIjozLCJmaWxlIjoidGVzdC5qcyIsInNvdXJjZVJvb3QiOiIiLCJzb3VyY2VzIjpbInRlc3QudHMiXSwibmFtZXMiOltdLCJtYXBwaW5ncyI6IkFBQUEsT0FBTyxDQUFDLEdBQUcsQ0FBQyxPQUFPLENBQUMsQ0FBQztBQUNyQixPQUFPLENBQUMsR0FBRyxDQUFDLE9BQU8sQ0FBQyxDQUFDIn0=

Source map breaks down into:

"console": test.ts:1:0
".": test.ts:1:7
"log": test.ts:1:8
"(": test.ts:1:11
"'hello'": test.ts:1:12
")": test.ts:1:19
";": test.ts:1:20
"\n": test.ts:1:21  <-- line end
"console": test.ts:2:0
".": test.ts:2:7
"log": test.ts:2:8
"(": test.ts:2:11
"'world'": test.ts:2:12
")": test.ts:2:19
";": test.ts:2:20
"": test.ts:2:21  <-- line end

Expected behavior:

Line end characters left unmapped.

Actual behavior:

Line end characters are included in the mapping, with the column number that equals to the length of the line -- which exceeds the boundary, given that column number is 0-based in a source map.

The spec doesn't cover if mappings for line ending characters should be included. But this behavior breaks some tools (eg. source-map-explorer) with strict boundary checks.

Playground Link:

Related Issues:

Reproduce the issue with tsc --inlineSourceMap test.ts using the provided test.ts and inspect the inline source map in test.js. Trace how the compiler records mappings at line endings, then verify that the generated mappings no longer include those characters while the other mappings remain unchanged.