summary: Add list_sep keyword argument

This allows having lists on a single line instead of having each value
aligned on a new line.

docs/markdown/Reference-manual.md

@@ -1239,9 +1239,10 @@ pair doesn't appear twice. All sections will be collected and printed at
 the end of the configuration in the same order as they have been called.
 
 Keyword arguments:
+- `section` title to group a set of key/value pairs.
 - `bool_yn` if set to true, all boolean values will be replaced by green YES
   or red NO.
-- `section` title to group a set of key/value pairs.
+- `list_sep` *Since 0.54.0* string used to separate list values (e.g. `', '`).
 
 Example:
 ```meson

docs/markdown/snippets/summary.md

@@ -0,0 +1,5 @@
+## Summary improvements
+
+A new `list_sep` keyword argument has been added to `summary()` function.
+If defined and the value is a list, elements will be separated by the provided
+string instead of being aligned on a new line.

mesonbuild/interpreter.py

@@ -1791,6 +1791,9 @@ class Summary:
         bool_yn = kwargs.get('bool_yn', False)
         if not isinstance(bool_yn, bool):
             raise InterpreterException('bool_yn keyword argument must be boolean')
+        list_sep = kwargs.get('list_sep')
+        if list_sep is not None and not isinstance(list_sep, str):
+            raise InterpreterException('list_sep keyword argument must be string')
         for k, v in values.items():
             if k in self.sections[section]:
                 raise InterpreterException('Summary section {!r} already have key {!r}'.format(section, k))
@@ -1803,9 +1806,7 @@ class Summary:
                     formatted_values.append(mlog.green('YES') if i else mlog.red('NO'))
                 else:
                     formatted_values.append(i)
-            if not formatted_values:
-                formatted_values = ['']
-            self.sections[section][k] = formatted_values
+            self.sections[section][k] = (formatted_values, list_sep)
             self.max_key_len = max(self.max_key_len, len(k))
 
     def dump(self):
@@ -1815,11 +1816,14 @@ class Summary:
             if section:
                 mlog.log(' ', mlog.bold(section))
             for k, v in values.items():
+                v, list_sep = v
                 indent = self.max_key_len - len(k) + 3
-                mlog.log(' ' * indent, k + ':', v[0])
-                indent = self.max_key_len + 5
-                for i in v[1:]:
-                    mlog.log(' ' * indent, i)
+                end = ' ' if v else ''
+                mlog.log(' ' * indent, k + ':', end=end)
+                if list_sep is None:
+                    indent = self.max_key_len + 6
+                    list_sep = '\n' + ' ' * indent
+                mlog.log(*v, sep=list_sep)
         mlog.log('')  # newline
 
 
@@ -2949,7 +2953,8 @@ external dependencies (including libraries) must go to "dependencies".''')
         mlog.log(mlog.bold('Message:'), *args)
 
     @noArgsFlattening
-    @permittedKwargs({'section', 'bool_yn'})
+    @FeatureNewKwargs('summary', '0.54.0', ['list_sep'])
+    @permittedKwargs({'section', 'bool_yn', 'list_sep'})
     @FeatureNew('summary', '0.53.0')
     def func_summary(self, node, args, kwargs):
         if len(args) == 1:

run_unittests.py

@@ -4347,10 +4347,11 @@ recommended as it is not supported on some platforms''')
                          A list: string
                                  1
                                  True
-                     empty list: 
+                     empty list:
                        A number: 1
                             yes: YES
                              no: NO
+                      coma list: a, b, c
 
               Subprojects
                             sub: YES

test cases/unit/72 summary/meson.build

@@ -12,3 +12,4 @@ summary({'Some boolean': false,
 summary('A number', 1, section: 'Configuration')
 summary('yes', true, bool_yn : true, section: 'Configuration')
 summary('no', false, bool_yn : true, section: 'Configuration')
+summary('coma list', ['a', 'b', 'c'], list_sep: ', ', section: 'Configuration')