assert(): Make message argument optional

2 files changed, 20 insertions, 7 deletions

diff --git a/mesonbuild/ast/printer.py b/mesonbuild/ast/printer.py
index c6fb91a..f245a36 100644
--- a/mesonbuild/ast/printer.py
+++ b/mesonbuild/ast/printer.py
@@ -100,7 +100,7 @@ class AstPrinter(AstVisitor):
 
     def visit_ComparisonNode(self, node: mparser.ComparisonNode):
         node.left.accept(self)
-        self.append_padded(mparser.comparison_map[node.ctype], node)
+        self.append_padded(node.ctype, node)
         node.right.accept(self)
 
     def visit_ArithmeticNode(self, node: mparser.ArithmeticNode):
@@ -192,7 +192,10 @@ class AstPrinter(AstVisitor):
             if break_args:
                 self.newline()
         for key, val in node.kwargs.items():
-            self.append(key, node)
+            if isinstance(key, str):
+                self.append(key, node)
+            else:
+                key.accept(self)
             self.append_padded(':', node)
             val.accept(self)
             self.append(', ', node)
diff --git a/mesonbuild/interpreter.py b/mesonbuild/interpreter.py
index 024266e..d7f826c 100644
--- a/mesonbuild/interpreter.py
+++ b/mesonbuild/interpreter.py
@@ -2366,14 +2366,24 @@ external dependencies (including libraries) must go to "dependencies".''')
 
     @noKwargs
     def func_assert(self, node, args, kwargs):
-        if len(args) != 2:
-            raise InterpreterException('Assert takes exactly two arguments')
-        value, message = args
+        if len(args) == 1:
+            FeatureNew('assert function without message argument', '0.53.0').use(self.subproject)
+            value = args[0]
+            message = None
+        elif len(args) == 2:
+            value, message = args
+            if not isinstance(message, str):
+                raise InterpreterException('Assert message not a string.')
+        else:
+            raise InterpreterException('Assert takes between one and two arguments')
         if not isinstance(value, bool):
             raise InterpreterException('Assert value not bool.')
-        if not isinstance(message, str):
-            raise InterpreterException('Assert message not a string.')
         if not value:
+            if message is None:
+                from .ast import AstPrinter
+                printer = AstPrinter()
+                node.args.arguments[0].accept(printer)
+                message = printer.result
             raise InterpreterException('Assert failed: ' + message)
 
     def validate_arguments(self, args, argcount, arg_types):