Indent continuations after | and &&

This indents continuations after pipes and conjunctions if they contain
a newline.

Example:

    cmd1 &&
        cmd2

But it avoids the "double indent" if it indented unconditionally:

    cmd1 | begin
        cmd2
    end

More work towards improving #7252

src/parse_util.cpp

@@ -590,7 +590,8 @@ std::vector<int> parse_util_compute_indents(const wcstring &src) {
     // Visit all of our nodes. When we get a job_list or case_item_list, increment indent while
     // visiting its children.
     struct indent_visitor_t {
-        explicit indent_visitor_t(std::vector<int> &indents) : indents(indents) {}
+        indent_visitor_t(const wcstring &src, std::vector<int> &indents)
+            : src(src), indents(indents) {}
 
         void visit(const node_t &node) {
             int inc = 0;
@@ -612,9 +613,25 @@ std::vector<int> parse_util_compute_indents(const wcstring &src) {
                     }
                     break;
 
-                // Increment indents for piped remainders.
-                case type_t::job_continuation_list:
-                    if (node.as<job_continuation_list_t>()->count() > 0) {
+                // Increment indents for job_continuation_t if it contains a newline.
+                // This is a bit of a hack - it indents cases like:
+                //    cmd1 |
+                //    ....cmd2
+                // but avoids "double indenting" if there's no newline:
+                //   cmd1 | while cmd2
+                //   ....cmd3
+                //   end
+                // See #7252.
+                case type_t::job_continuation:
+                    if (has_newline(node.as<job_continuation_t>()->newlines)) {
+                        inc = 1;
+                        dec = 1;
+                    }
+                    break;
+
+                // Likewise for && and ||.
+                case type_t::job_conjunction_continuation:
+                    if (has_newline(node.as<job_conjunction_continuation_t>()->newlines)) {
                         inc = 1;
                         dec = 1;
                     }
@@ -675,6 +692,11 @@ std::vector<int> parse_util_compute_indents(const wcstring &src) {
             indent -= dec;
         }
 
+        /// \return whether a maybe_newlines node contains at least one newline.
+        bool has_newline(const maybe_newlines_t &nls) const {
+            return nls.source(src).find(L'\n') != wcstring::npos;
+        }
+
         // The one-past-the-last index of the most recently encountered leaf node.
         // We use this to populate the indents even if there's no tokens in the range.
         size_t last_leaf_end{0};
@@ -682,6 +704,9 @@ std::vector<int> parse_util_compute_indents(const wcstring &src) {
         // The last indent which we assigned.
         int last_indent{-1};
 
+        // The source we are indenting.
+        const wcstring &src;
+
         // List of indents, which we populate.
         std::vector<int> &indents;
 
@@ -690,7 +715,7 @@ std::vector<int> parse_util_compute_indents(const wcstring &src) {
         int indent{-1};
     };
 
-    indent_visitor_t iv(indents);
+    indent_visitor_t iv(src, indents);
     node_visitor(iv).accept(ast.top());
 
     // All newlines now get the *next* indent.

tests/checks/indent.fish

@@ -233,9 +233,9 @@ begin
 # comment
 end
 ' | $fish_indent
-#CHECK: begin
-#CHECK: {{    }}# comment
-#CHECK: end
+#CHECK: {{^}}begin
+#CHECK: {{^    }}# comment
+#CHECK: {{^}}end
 
 echo -n '
 begin
@@ -243,17 +243,17 @@ cmd
 # comment
 end
 ' | $fish_indent
-#CHECK: begin
-#CHECK: {{    }}cmd
-#CHECK: {{    }}# comment
-#CHECK: end
+#CHECK: {{^}}begin
+#CHECK: {{^    }}cmd
+#CHECK: {{^    }}# comment
+#CHECK: {{^}}end
 
 echo -n '
 cmd \\
 continuation
 ' | $fish_indent
-#CHECK: cmd \
-#CHECK: {{    }}continuation
+#CHECK: {{^}}cmd \
+#CHECK: {{^    }}continuation
 
 echo -n '
 begin
@@ -261,10 +261,10 @@ cmd \
 continuation
 end
 ' | $fish_indent
-#CHECK: begin
-#CHECK: {{    }}cmd \
-#CHECK: {{    }}{{    }}continuation
-#CHECK: end
+#CHECK: {{^}}begin
+#CHECK: {{^    }}cmd \
+#CHECK: {{^    }}{{    }}continuation
+#CHECK: {{^}}end
 
 
 echo -n '
@@ -350,15 +350,15 @@ echo 'foo &&
   #
 bar' | $fish_indent
 #CHECK: {{^}}foo &&
-#CHECK: {{^}}#
-#CHECK: {{^}}bar
+#CHECK: {{^    }}#
+#CHECK: {{    }}bar
 
 echo 'command 1 |
 command 1 cont ||
 command 2' | $fish_indent
 #CHECK: {{^}}command 1 |
 #CHECK: {{^    }}command 1 cont ||
-#CHECK: {{^}}command 2
+#CHECK: {{^    }}command 2
 
 echo " foo" | fish_indent --check
 echo $status