Debug Failure. False expression

[ca0v]

Trying to do a composite build modeled after microsoft/typescript but generating AMD modules fails:

Error: Debug Failure. False expression.
    at mergeSymbol (H:\code\ca0v\speech-lab\node_modules\typescript\lib\tsc.js:26088:26)
    at H:\code\ca0v\speech-lab\node_modules\typescript\lib\tsc.js:26187:47
    at Map.forEach (<anonymous>)
    at mergeSymbolTable (H:\code\ca0v\speech-lab\node_modules\typescript\lib\tsc.js:26185:20)
    at initializeTypeChecker (H:\code\ca0v\speech-lab\node_modules\typescript\lib\tsc.js:49309:21)
    at Object.createTypeChecker (H:\code\ca0v\speech-lab\node_modules\typescript\lib\tsc.js:25950:9)
    at Object.getTypeChecker (H:\code\ca0v\speech-lab\node_modules\typescript\lib\tsc.js:72860:79)
    at getReferencedFiles (H:\code\ca0v\speech-lab\node_modules\typescript\lib\tsc.js:74290:43)
    at Object.create (H:\code\ca0v\speech-lab\node_modules\typescript\lib\tsc.js:74329:41)
    at createBuilderProgramState (H:\code\ca0v\speech-lab\node_modules\typescript\lib\tsc.js:74572:37)

You can find a link to the project on https://stackoverflow.com/questions/55348498/problems-building-with-typescript-transpiler-tsc-using-the-build-flag, but basically if you set the module to "amd" it fails to transpiler (works fine when outFile -> outDir).

[RyanCavanaugh]

@sandersn A symbol table bug appears!

[sandersn]

Repro steps:

> git clone git@github.com:ca0v/speech-lab
> cd speech-lab
> npm install
> cd tsc
> tsc -b

Edit: The following commands have no error:

> cd compiler
> tsc
> cd ../tsc
> tsc
# But this still errors, even with 'compiler' built
> tsc -b

[sandersn]

Looks like the program has duplicates in its list of source files.

[sandersn]

Adding asserts to program.ts:addFileToFilesByName moves this error a lot closer to its origin:

function addFileToFilesByName(file: SourceFile | undefined, path: Path, redirectedPath: Path | undefined) {
    Debug.assert(!filesByName.has(path), "duplicate path");
    if (redirectedPath) {
	Debug.assert(!filesByName.has(redirectedPath), "duplicate redirected path");
	filesByName.set(redirectedPath, file);
	filesByName.set(path, file || false);
    }
    else {
	filesByName.set(path, file);
    }
}

[sheetalkamat]

Had encountered this while working on #29262 but when it got closed in favor of #30288 this issue was missed. f2862b2 handled this then but need to figure out what would be correct approach with new PR.