Subject: 25.1.50; backquotes cause testcover to report 1value errors
From: Gemini Lasswell <[email-masked]>
To: [email-masked]
Date: Thu, 22 Sep 2016 08:52:28 -0700
List-Id: <debbugs-submit.debbugs.gnu.org>

Backquote syntax can cause testcover to report "Value of form marked with ‘1value’ does vary” errors. Here is some code with two different variations of the problem:

(defmacro my-lambda (&rest body)
  `(lambda () ,@body))

(defun my-example ()
  (let ((lambda-1 (my-lambda (message "lambda-1")))
	(lambda-2 (my-lambda (message "lambda-2"))))
    (funcall lambda-1)
    (funcall lambda-2)))

(defmacro my-print-symbol (name)
  `(message "the symbol is %s" ',name))

(defun my-example-2 ()
  (my-print-symbol foo)
  (my-print-symbol bar))

To reproduce the bug:
1. save the above code into a file
2. emacs -Q
3. M-x eval-expression RET (require ‘testcover) RET
4. M-x testcover-start RET filename RET

To make the attached stack trace:
5. M-x toggle-debug-on-error RET
6. M-x eval-expression RET (my-example-2) RET

In my opinion testcover should not be claiming that it is an error if its 1value determination is incorrect. There is no error in the code being tested, there is just a shortcoming in the heuristics that testcover is using to figure out what color splotch to put on the line. But if a form has returned a second value, that code has had adequate coverage and no splotch is necessary.

In GNU Emacs 25.1.50.4 (x86_64-apple-darwin15.6.0, NS appkit-1404.47 Version 10.11.6 (Build 15G1004))
of 2016-09-19 built on malolo.local
Windowing system distributor 'Apple', version 10.3.1404
Recent messages:
You can run the command ‘eval-expression’ with M-:
testcover
Edebug: my-lambda
Edebug: my-example
Eager macro-expansion failure: (error "Value of form marked with ‘1value’ does vary: (lambda nil (message lambda-2))")
Edebug: my-print-symbol
Edebug: my-example-2
Eager macro-expansion failure: (error "Value of form marked with ‘1value’ does vary: (message the symbol is %s (quote bar))")
You can run the command ‘testcover-start’ with M-x tes-s RET
Eager macro-expansion failure: (error "Value of form marked with ‘1value’ does vary: (message the symbol is %s (quote bar))")

Configured using:
'configure --with-ns'

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Memory information:
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