The assignment type-checking code previously bounced around a lot
between the LHS and RHS sides of the assignment. But there's actually
a very simple, consistent pattern to how to type check assignments:
1. Check the RHS expression.
2. If the LHS expression is an identifier that was declared in this
statement and it doesn't have an explicit type, give it the RHS
expression's default type.
3. Check the LHS expression.
4. Try assigning the RHS expression to the LHS expression, adding
implicit conversions as needed.
This CL implements this algorithm, and refactors tcAssign and
tcAssignList to use a common implementation. It also fixes the error
messages to consistently say just "1 variable" or "1 value", rather
than occasionally "1 variables" or "1 values".
Fixes#43348.
Passes toolstash -cmp.
Change-Id: I749cb8d6ccbc7d22cd7cb0a381f58a39fc2696b5
Reviewed-on: https://go-review.googlesource.com/c/go/+/280112
Trust: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Triaged and adjusted more test/fixedbugs/* tests.
Change-Id: I80b9ead2445bb8d126b7d79db4bea9ddcb225a84
Reviewed-on: https://go-review.googlesource.com/c/go/+/276812
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Show a more specifc error message in the form of "%d variables but %v
returns %d values" if an assignment mismatch occurs with a function
or method call on the right.
Fixes#27595
Change-Id: Ibc97d070662b08f150ac22d686059cf224e012ab
Reviewed-on: https://go-review.googlesource.com/135575
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
