Fix trailing comma in YAS (#1226)

Closes #1225

Author: penelopeysm

HISTORY_v2.md

@@ -1,3 +1,7 @@
+# v2.11.2
+
+Fixed a bug where YASStyle would insert a trailing comma for a function call with zero arguments, which is invalid Julia syntax. (#1225, #1226)
+
 # v2.11.1
 
 Fixed a bug where formatting a do-block with no argument after the `do` would cause YASStyle to crash. (#1219, #1221)

Project.toml

@@ -1,6 +1,6 @@
 name = "JuliaFormatter"
 uuid = "98e50ef6-434e-11e9-1051-2b60c6c9e899"
-version = "2.11.1"
+version = "2.11.2"
 authors = ["Dominique Luna <dluna132@gmail.com> and contributors"]
 
 [workspace]

src/styles/yas/pretty.jl

@@ -362,7 +362,12 @@ function p_call(
             # case where the last argument is followed by a comment, the closing paren will
             # be placed on the next line, and in that case we want to allow a trailing
             # comma.
-            k === K")" && add_node!(t, TrailingComma(), s)
+            # If `i == first_arg_idx`, then the function call is empty. In such cases adding
+            # a trailing comma causes a syntax error, so don't do it
+            if k === K")" && i != first_arg_idx
+                add_node!(t, TrailingComma(), s)
+            end
+
             add_node!(
                 t,
                 n,

test/issues.jl

@@ -3581,6 +3581,27 @@ end
         end"""
         test_format(s, s, YASStyle(); margin=30)
     end
+
+    @testset "1225 YAS trailing comma with zero args" begin
+        s_ = """
+        f(
+             # Hi
+        )"""
+        s = """
+        f(
+          # Hi
+          )"""
+        test_format(s_, s, YASStyle())
+
+        s_ = """
+        f(
+             #= Hi =#
+        )"""
+        s = """
+        f(
+          #= Hi =#)"""
+        test_format(s_, s, YASStyle())
+    end
 end
 
 end