fish_indent: Allow semicolons for and and or

As mentioned in #2900, something like

```fish
test -n "$var"; and set -l foo $var
```

is sufficiently idiomatic that it should be allowable.

Also fixes some additional weirdness with semicolons.

src/fish_indent.cpp

@@ -224,17 +224,27 @@ void prettifier_t::prettify_node(const parse_node_tree_t &tree, node_offset_t no
             // instead of the semicolons. Semicolons are just ignored, unless they are followed by a
             // command. So `echo;` removes the semicolon, but `echo; echo` removes it and adds a
             // newline.
+            last_was_semicolon = false;
             if (node.get_source(source) == L"\n") {
                 append_newline();
-            } else {
+            } else if (!has_new_line) {
+                // The semicolon is only useful if we haven't just had a newline.
                 last_was_semicolon = true;
             }
         } else if ((node_type >= FIRST_PARSE_TOKEN_TYPE && node_type <= LAST_PARSE_TOKEN_TYPE) ||
                    node_type == parse_special_type_parse_error) {
             if (last_was_semicolon) {
-                append_newline();
+                // We keep the semicolon for `; and` and `; or`,
+                // others we turn into newlines.
+                if (node.keyword != parse_keyword_and
+                    && node.keyword != parse_keyword_or) {
+                    append_newline();
+                } else {
+                    output.push_back(L';');
+                }
                 last_was_semicolon = false;
             }
+
             if (node.keyword != parse_keyword_none) {
                 append_whitespace(node_indent);
                 output.append(keyword_description(node.keyword));

tests/indent.in

@@ -1,3 +1,5 @@
+set -l indent ../test/root/bin/fish_indent
+
 echo Test1
 echo -n '
 begin
@@ -5,7 +7,7 @@ echo hi
 
 
 end | cat | cat | begin ; echo hi ; end | begin ; begin ; echo hi ; end ; end arg
-' | ../test/root/bin/fish_indent
+' | $indent
 
 echo \nTest2
 echo -n '
@@ -18,7 +20,7 @@ switch aloha
       echo hi
 
 end
-' | ../test/root/bin/fish_indent
+' | $indent
 
 echo \nTest3
 echo -n '
@@ -33,7 +35,7 @@ function hello_world
 
    echo hello
                   end
-' | ../test/root/bin/fish_indent
+' | $indent
 
 echo \nTest4
 echo -n '
@@ -53,7 +55,7 @@ switch foo #abc
 qqq
    case "*"
        echo sup
-end' | ../test/root/bin/fish_indent
+end' | $indent
 
 echo \nTest5
 echo -n '
@@ -65,7 +67,7 @@ switch beta
        echo delta
 end
 end
-' | ../test/root/bin/fish_indent -i
+' | $indent -i
 
 echo \nTest6
 # Test errors
@@ -75,20 +77,20 @@ echo hi
 else
 echo bye
 end; echo alpha "
-' | ../test/root/bin/fish_indent
+' | $indent
 
 echo \nTest7
 # issue 1665
 echo -n '
 if begin ; false; end; echo hi ; end
 while begin ; false; end; echo hi ; end
-' | ../test/root/bin/fish_indent
+' | $indent
 
 echo \nTest redir formatting
 # issue 2899
 echo -n '
 echo < stdin >>appended yes 2>&1 no > stdout maybe 2>&    4 | cat 2>| cat
-' | ../test/root/bin/fish_indent
+' | $indent
 
 echo \nTest normalization of keywords
 # issue 2921
@@ -122,7 +124,13 @@ echo abc;end
 echo hi |
 
 echo bye
-' | ../test/root/bin/fish_indent
+' | $indent
 
-echo 'a;;;;;;' | ../test/root/bin/fish_indent
+echo 'a;;;;;;' | $indent
-echo 'echo; echo' | ../test/root/bin/fish_indent
+echo 'echo; echo' | $indent
+
+# Check that we keep semicolons for and and or, but only on the same line.
+printf '%s\n' "a; and b" | $indent
+printf '%s\n' "a;" "and b" | $indent
+printf '%s\n' "a" "; and b" | $indent
+printf '%s\n' "a; b" | $indent

tests/indent.out

@@ -36,7 +36,6 @@ function hello_world
     echo sup
     echo hello
 
-
     echo hello
 end
 
@@ -128,3 +127,10 @@ echo bye
 a
 echo
 echo
+a; and b
+a
+and b
+a
+and b
+a
+b