deprecate lda a

docs/changelog/index.html

@@ -98,6 +98,7 @@ <h3>Deprecated features:</h3>
 			<li><code>incbin file.bin -&gt; target</code>: put an <code>org</code> or <code>freespace</code> command before the incbin.</li>
 			<li><code class="65c816_asar">if a = b</code>: use <code class="65c816_asar">if a == b</code> instead.</li>
 			<li>Comments starting with <code>;[[</code> : These mark the start of block comments in Asar 2.0, so either remove the <code>[[</code> for the time being, or make the commented line end with a <code>]]</code>.</li>
+			<li>Using <code>A</code> as a label name ambiguously, e.g. <code>lda a</code>: in Asar 2 this will be interpreted as trying to use the "A" addressing mode, and will give an error. You can use <code>A+0</code> if you really must refer to the label as is.</li>
 		</ul></div>
 
 		<hr />

src/asar/arch-65816.cpp

@@ -178,6 +178,7 @@ bool asblock_65816(char** word, int numwords)
 opAFallback:
 			snes_label tmp;
 			if (pass && !labelval(par, &tmp)) return false;
+			asar_throw_warning(1, warning_id_feature_deprecated, "using A as a label name", "rename your label to _a or something, or use a+0 to disambiguate the addressing mode");
 			len=getlen(par);
 			num=tmp.pos;
 		}