user315: This question is for aspiring rules lawyers.
The FIDE's new laws of chess, effective Jan. 1, 2018, patch ambiguities and other subtle problems. I like the new laws. When it comes to game mechanics, I hope that the new laws remain permanently, so may I now ask a totally pedantic technical question regarding a ridiculous but (as far as I know) legal situation?
Under the new laws, suppose that

you have made 50 moves since the last pawn move or capture,
I have made 49 moves since the last pawn move or capture, and
it is my turn to move.

Suppose that my 50th move checkmates you. Ridiculously however, suppose that—simultaneous with my move—I claim a 50-move draw. Do I read the laws right: this game is a draw?
Before answering, you might compare law 9.3.1 against law 9.6.2. The new laws are more carefully worded than the old laws were, so I am unsure that the effect in question is a mere unintentional artifact of unfortunate wording. I suspect that the effect might be deliberate, rather.
Can you shed any light in the matter?
Of course, I am not asking why a checkmating player would choose to waive the checkmate in favor of a draw, but am only probing an odd corner of the laws' logic.
See also this related question and answer from before the recent changes in the laws.
UPDATE
It turns out that my question is a duplicate of the linked question, if you look at it the right way.  Morever, an answer to the linked question quotes Geurt Gijssen, an authoritative source. Gijssen answers the question indirectly by answering the inverse question. If I read Gijssen correctly, then a player can indeed claim a 50-move draw while checkmating, and in that case the draw claim would take precedence.
Weird, eh?
One could question the relevance of Gijssen's comments, since Gijssen (if I recall) retired before the most recent revision cycle, except that the revision seems to come to address questions Gijssen himself had considered or raised.
This sort of question is interesting if one is, for example, programming a computer interface for online chess play, for the programmer must implement the law in question the one way or the other. Just leaving it ambiguous would probably not be a reasonable option in that context.
I also note that players reading the rule in this very question thread are reaching opposite conclusions regarding the rule's meaning in the present case. Academic questions like this can be significant from a rules-logical perspective (as anyone who has programmed game rules into a computer might verify), even if the situation the question targets might never arise during over-the-board play. No game rule wishes players to reach opposite conclusions regarding its meaning, does it?
Two computer programs with different understandings of the rules might deadlock, if set to play one another, for example.
FURTHER UPDATE
The answers have been really interesting, at least to me.
An actual arbiter in this thread has now persuaded me to the opposite conclusion. He has persuaded me that the checkmate would take precedence, after all.
Unfortunately, one probably cannot but conclude that the rule is ambiguous in the sense that the rule evidently supports reasonable, experienced players to reach opposite conclusions regarding the rule's meaning in this instance.

user9025: It appears that 1.4.2 and 5.1.1 on that page would take precedence.

1.4.2 The opponent whose king has been checkmated has lost the game.   
5.1.1 The game is won by the player who has checkmated his opponent’s king. This immediately ends the game, provided that the move producing
  the checkmate position was in accordance with Article 3 and Articles
  4.2 – 4.7.


user8844: I would let the checkmate stand but the true answer is that it does not matter. The player has the right to offer a draw at any time and the claim according to article 9.3 is also a draw offer. You are concerned with a peculiar situation where player A wants a draw and does not want to win, for whatever reason, while player B does not want to draw (even at the cost of a loss). Therefore, the question you really ask is whether claiming a draw according to article 9.3, if the intended move delivers a checkmate, can secure you the draw. Abstracting away from the possibility that you can choose any other legal move and claim on that basis, the answer to that question is that yes, there is a way. 
You can claim the draw as you proposed and if the arbiter rejects the claim because the checkmate stands then you simply let your time run out and the game is a draw because the opponent cannot checkmate you by any series of legal moves. This is since you have committed to play the checkmating move thus there is no way how the opponent could checkmate you as they are going to be checkmated on next move. A catch is that not all arbiters may be comfortable with this interpretation and they may declare the game lost for you even though they shouldn't. But this situation will never happen anyway, right? It is purely of academic interest. 
I would let the checkmate stand for two reasons.

Consider this variation on your question, you claim the draw as you proposed but the intended move does not deliver a checkmate but rather captures a pawn. Again, as you point out, the move has not yet been made, hence, the pawn is never captured. Still the claim should be rejected. To assess the validity of the claim you need to consider the position as if the move had been played. I would apply this reasoning to the checkmate situation. If there is a checkmate after the intended 50th move, the validity of the claim cannot be assessed since the game will have finished. Of course, you can choose another move and claim the draw. 
Article 9.6.2 explicitly says that the checkmate takes precedence, therefore, I would apply it to article 9.3.1 too (not 9.3.2 since the game would have already finished once the checkmate is on the board). The crux is whether article 9.3.1 omits to mention this precedence intentionally. If this was so then what would the intention be? The intention would have to be to allow the player to secure a draw instead of the win and this is pointless as I explained earlier. Therefore, this difference in the wordings is not intentional, in fact, article 9.3.1 does not require it while article 9.6.2 does. In the situation described in 9.6.2 the player does not have the option not to claim, the amendment protects the stronger player here. 

It does not really matter though. Imagine 50 moves without a capture or moving a pawn have already been played. Then the player can either claim according to 9.3.1 as you proposed or they can claim according to 9.3.2 even though they could deliver a checkmate next move. In the latter case it is an unambiguous draw. It does not make much sense to obtain to different results depending on which way you claim the same thing (yes, I am undermining my earlier arguments) but either way you get something out of it that does not make much sense. But again, no one forces you to claim a draw with a checkmating move. In fact, this may trigger a punishment according to article 12.9 for putting chess in disrepute. 
I am afraid you misunderstand Geurt Gijssen's answer. He did not answer your question at all, he said that the player having the move would not make the claim, because it does not make sense, and the opponent is not allowed to make the claim, because it is not their move. It does not follow from his answer that he would agree with the claim if the player really made it.

user14979: The Laws of Chess say:

9.3 The game is drawn, upon a correct claim by the player having the move, if
a) he  writes his  move on  his  scoresheet  and  declares  to  the 
  arbiter  his  intention to make this move, which shall result in the
  last 50 moves having been made by each player without the movement of
  any pawn and without any capture, or
b) the last 50 consecutive  moves  have  been  made  by  each  player
  without the movement of any pawn and without any capture.

So you don't claim the draw WHILE you checkmate but BEFORE you make the checkmate move. Therefore there is no checkmate, but the game is drawn.
If you don't claim the draw but execute your checkmate move, your opponent cannot claim a draw by 9.3.b) because the game is finished by your checkmate.

315: <p>This question is for aspiring rules lawyers.</p>

<p>The FIDE's <a href="https://www.fide.com/fide/handbook.html?id=208&amp;view=article" rel="noreferrer">new laws of chess,</a> effective Jan. 1, 2018, patch ambiguities and other subtle problems. I like the new laws. When it comes to game mechanics, I hope that the new laws remain permanently, so may I now ask a totally pedantic technical question regarding a ridiculous but (as far as I know) legal situation?</p>

<p>Under the new laws, suppose that</p>

<ul>
<li>you have made 50 moves since the last pawn move or capture,</li>
<li>I have made 49 moves since the last pawn move or capture, and</li>
<li>it is my turn to move.</li>
</ul>

<p>Suppose that my 50th move checkmates you. Ridiculously however, suppose that—simultaneous with my move—I claim a 50-move draw. Do I read the laws right: this game is a draw?</p>

<p>Before answering, you might compare law 9.3.1 against law 9.6.2. The new laws are more carefully worded than the old laws were, so I am unsure that the effect in question is a mere unintentional artifact of unfortunate wording. I <em>suspect</em> that the effect might be deliberate, rather.</p>

<p>Can you shed any light in the matter?</p>

<p>Of course, I am not asking why a checkmating player would choose to waive the checkmate in favor of a draw, but am only probing an odd corner of the laws' logic.</p>

<p>See also <a href="https://chess.stackexchange.com/questions/12613/does-checkmate-over-ride-50-move-violation">this related question and answer</a> from before the recent changes in the laws.</p>

<p><strong>UPDATE</strong></p>

<p>It turns out that my question is a duplicate of the linked question, if you look at it the right way.  Morever, an answer to the linked question quotes Geurt Gijssen, an authoritative source. Gijssen answers the question indirectly by answering the inverse question. If I read Gijssen correctly, then a player can indeed claim a 50-move draw while checkmating, <em>and in that case the draw claim would take precedence.</em></p>

<p>Weird, eh?</p>

<p>One could question the relevance of Gijssen's comments, since Gijssen (if I recall) retired before the most recent revision cycle, except that the revision seems to come to address questions Gijssen himself had considered or raised.</p>

<p>This sort of question is interesting if one is, for example, programming a computer interface for online chess play, for the programmer must implement the law in question the one way or the other. Just leaving it ambiguous would probably not be a reasonable option in that context.</p>

<p>I also note that players reading the rule in this very question thread are reaching opposite conclusions regarding the rule's meaning in the present case. Academic questions like this can be significant from a rules-logical perspective (as anyone who has programmed game rules into a computer might verify), even if the situation the question targets might never arise during over-the-board play. No game rule <em>wishes</em> players to reach opposite conclusions regarding its meaning, does it?</p>

<p>Two computer programs with different understandings of the rules might deadlock, if set to play one another, for example.</p>

<p><strong>FURTHER UPDATE</strong></p>

<p>The answers have been really interesting, at least to me.</p>

<p>An actual arbiter in this thread has now persuaded me to the opposite conclusion. He has persuaded me that the checkmate would take precedence, after all.</p>

<p>Unfortunately, one probably cannot but conclude that the rule is ambiguous in the sense that the rule evidently supports reasonable, experienced players to reach opposite conclusions regarding the rule's meaning in this instance.</p>
 9025: <p>It appears that 1.4.2 and 5.1.1 on that page would take precedence.</p>

<blockquote>
  <p>1.4.2 The opponent whose king has been checkmated has lost the game.   </p>
  
  <p>5.1.1 The game is won by the player who has checkmated his opponent’s king. This immediately ends the game, provided that the move producing
  the checkmate position was in accordance with Article 3 and Articles
  4.2 – 4.7.</p>
</blockquote>
 8844: <p>I would let the checkmate stand but the true answer is that it does not matter. The player has the right to offer a draw at any time and the claim according to article 9.3 is also a draw offer. You are concerned with a peculiar situation where player A wants a draw and does not want to win, for whatever reason, while player B does not want to draw (even at the cost of a loss). Therefore, the question you really ask is whether claiming a draw according to article 9.3, if the intended move delivers a checkmate, can secure you the draw. Abstracting away from the possibility that you can choose any other legal move and claim on that basis, the answer to that question is that yes, there is a way. </p>

<p>You can claim the draw as you proposed and if the arbiter rejects the claim because the checkmate stands then you simply let your time run out and the game is a draw because the opponent cannot checkmate you by any series of legal moves. This is since you have committed to play the checkmating move thus there is no way how the opponent could checkmate you as they are going to be checkmated on next move. A catch is that not all arbiters may be comfortable with this interpretation and they may declare the game lost for you even though they shouldn't. But this situation will never happen anyway, right? It is purely of academic interest. </p>

<p>I would let the checkmate stand for two reasons.</p>

<ol>
<li>Consider this variation on your question, you claim the draw as you proposed but the intended move does not deliver a checkmate but rather captures a pawn. Again, as you point out, the move has not yet been made, hence, the pawn is never captured. Still the claim should be rejected. To assess the validity of the claim you need to consider the position as if the move had been played. I would apply this reasoning to the checkmate situation. If there is a checkmate after the intended 50th move, the validity of the claim cannot be assessed since the game will have finished. Of course, you can choose another move and claim the draw. </li>
<li>Article 9.6.2 explicitly says that the checkmate takes precedence, therefore, I would apply it to article 9.3.1 too (not 9.3.2 since the game would have already finished once the checkmate is on the board). The crux is whether article 9.3.1 omits to mention this precedence intentionally. If this was so then what would the intention be? The intention would have to be to allow the player to secure a draw instead of the win and this is pointless as I explained earlier. Therefore, this difference in the wordings is not intentional, in fact, article 9.3.1 does not require it while article 9.6.2 does. In the situation described in 9.6.2 the player does not have the option not to claim, the amendment protects the stronger player here. </li>
</ol>

<p>It does not really matter though. Imagine 50 moves without a capture or moving a pawn have already been played. Then the player can either claim according to 9.3.1 as you proposed or they can claim according to 9.3.2 even though they could deliver a checkmate next move. In the latter case it is an unambiguous draw. It does not make much sense to obtain to different results depending on which way you claim the same thing (yes, I am undermining my earlier arguments) but either way you get something out of it that does not make much sense. But again, no one forces you to claim a draw with a checkmating move. In fact, this may trigger a punishment according to article 12.9 for putting chess in disrepute. </p>

<p>I am afraid you misunderstand Geurt Gijssen's answer. He did not answer your question at all, he said that the player having the move would not make the claim, because it does not make sense, and the opponent is not allowed to make the claim, because it is not their move. It does not follow from his answer that he would agree with the claim if the player really made it.</p>
 14979: <p>The Laws of Chess say:</p>

<blockquote>
  <p>9.3 The game is drawn, upon a correct claim by the player having the move, if</p>
  
  <p>a) he  writes his  move on  his  scoresheet  and  declares  to  the 
  arbiter  his  intention to make this move, which shall result in the
  last 50 moves having been made by each player without the movement of
  any pawn and without any capture, or</p>
  
  <p>b) the last 50 consecutive  moves  have  been  made  by  each  player
  without the movement of any pawn and without any capture.</p>
</blockquote>

<p>So you don't claim the draw WHILE you checkmate but BEFORE you make the checkmate move. Therefore there is no checkmate, but the game is drawn.</p>

<p>If you don't claim the draw but execute your checkmate move, your opponent cannot claim a draw by 9.3.b) because the game is finished by your checkmate.</p>
