nate-chandler 5cddc40335 Diagnose missing expr in non-void single-expr func. [52025782] (#25802) ...

* Diagnose missing expr in non-void single-expr func. [52025782]

After SE-0255, compiling

```
func foo() -> Int {
    return
}
```

would result in a diagnostic without source location:

```
<unknown>:0: error: cannot convert return expression of type '()' to
```

Now, it results in

```
filename.swift:8:5: error: non-void function should return a value
    return
    ^
```

as it did prior to SE-0255.

To achieve that, during type checking for statements, when the
StmtChecker visits return statements, check whether we are within a
non-void-returning, single-expression function and that that single
expression is an implicit empty tuple.  (An empty implicit tuple is
added as the result of a resultless return statement that appears as the
only element in a single-expression function.)

To facilitate that, `hasSingleExpressionBody` and
`getSingleExpressionBody` was added to `AnyFunctionRef` and added
`getSingleExpressionBody` to `AbstractClosureExpr` (which already had
`hasSingleExpressionBody`).

rdar://problem/52025782

2019-07-02 09:17:37 -07:00

8.7 KiB

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