Move value in protocol errors to its own line (#14003)

lib/elixir/lib/exception.ex

@@ -1997,8 +1997,23 @@ defmodule Protocol.UndefinedError do
 
   @impl true
   def message(%{protocol: protocol, value: value, description: description}) do
-    "protocol #{inspect(protocol)} not implemented for #{inspect(value)} of type " <>
-      value_type(value) <> maybe_description(description) <> maybe_available(protocol)
+    inspected =
+      value
+      |> inspect(pretty: true)
+      # Indent only lines with contents on them
+      |> String.replace(~r/^(?=.+)/m, "    ")
+
+    "protocol #{inspect(protocol)} not implemented for type " <>
+      value_type(value) <>
+      maybe_description(description) <>
+      maybe_available(protocol) <>
+      """
+
+
+      Got value:
+
+      #{inspected}
+      """
   end
 
   defp value_type(%{__struct__: struct}), do: "#{inspect(struct)} (a struct)"

lib/elixir/test/elixir/inspect_test.exs

@@ -526,16 +526,20 @@ defmodule Inspect.MapTest do
     # Inspect.Error is raised here when we tried to print the error message
     # called by another exception (Protocol.UndefinedError in this case)
     exception_message = ~s'''
-    protocol Enumerable not implemented for #Inspect.Error<
-      got ArgumentError with message:
+    protocol Enumerable not implemented for type Inspect.MapTest.Failing (a struct)
 
-          """
-          errors were found at the given arguments:
+    Got value:
 
-            * 1st argument: not an atom
-          """
+        #Inspect.Error<
+          got ArgumentError with message:
 
-      while inspecting:
+              """
+              errors were found at the given arguments:
+
+                * 1st argument: not an atom
+              """
+
+          while inspecting:
 
     '''
 
@@ -926,7 +930,11 @@ defmodule Inspect.CustomProtocolTest do
     got Protocol.UndefinedError with message:
 
         """
-        protocol Inspect.CustomProtocolTest.CustomInspect not implemented for %Inspect.CustomProtocolTest.MissingImplementation{} of type Inspect.CustomProtocolTest.MissingImplementation (a struct)
+        protocol Inspect.CustomProtocolTest.CustomInspect not implemented for type Inspect.CustomProtocolTest.MissingImplementation (a struct)
+
+        Got value:
+
+            %Inspect.CustomProtocolTest.MissingImplementation{}
         """
 
     while inspecting:
@@ -953,7 +961,11 @@ defmodule Inspect.CustomProtocolTest do
       got Protocol.UndefinedError with message:
 
           """
-          protocol Inspect.CustomProtocolTest.CustomInspect not implemented for %Inspect.CustomProtocolTest.MissingImplementation{} of type Inspect.CustomProtocolTest.MissingImplementation (a struct)
+          protocol Inspect.CustomProtocolTest.CustomInspect not implemented for type Inspect.CustomProtocolTest.MissingImplementation (a struct)
+
+          Got value:
+
+              %Inspect.CustomProtocolTest.MissingImplementation{}
           """
 
       while inspecting:

lib/elixir/test/elixir/protocol/consolidation_test.exs

@@ -182,8 +182,9 @@ defmodule Protocol.ConsolidationTest do
 
   test "protocol not implemented" do
     message =
-      "protocol Protocol.ConsolidationTest.Sample not implemented for :foo of type Atom. " <>
-        "This protocol is implemented for the following type(s): Protocol.ConsolidationTest.ImplStruct"
+      "protocol Protocol.ConsolidationTest.Sample not implemented for type Atom. " <>
+        "This protocol is implemented for the following type(s): Protocol.ConsolidationTest.ImplStruct" <>
+        "\n\nGot value:\n\n    :foo\n"
 
     assert_raise Protocol.UndefinedError, message, fn ->
       sample = String.to_atom("Elixir.Protocol.ConsolidationTest.Sample")

lib/elixir/test/elixir/protocol_test.exs

@@ -113,7 +113,14 @@ defmodule ProtocolTest do
   end
 
   test "protocol not implemented" do
-    message = "protocol ProtocolTest.Sample not implemented for :foo of type Atom"
+    message =
+      """
+      protocol ProtocolTest.Sample not implemented for type Atom
+
+      Got value:
+
+          :foo
+      """
 
     assert_raise Protocol.UndefinedError, message, fn ->
       sample = String.to_atom("Elixir.ProtocolTest.Sample")

lib/elixir/test/elixir/string/chars_test.exs

@@ -105,39 +105,54 @@ defmodule String.Chars.ErrorsTest do
 
   test "bitstring" do
     message =
-      "protocol String.Chars not implemented for <<0, 1::size(4)>> of type BitString, cannot convert a bitstring to a string"
+      """
+      protocol String.Chars not implemented for type BitString, cannot convert a bitstring to a string
+
+      Got value:
+
+          <<0, 1::size(4)>>
+      """
 
     assert_raise Protocol.UndefinedError, message, fn ->
       to_string(<<1::size(12)-integer-signed>>)
     end
   end
 
   test "tuple" do
-    message = "protocol String.Chars not implemented for {1, 2, 3} of type Tuple"
+    message = """
+    protocol String.Chars not implemented for type Tuple
+
+    Got value:
+
+        {1, 2, 3}
+    """
 
     assert_raise Protocol.UndefinedError, message, fn ->
       to_string({1, 2, 3})
     end
   end
 
   test "PID" do
-    message = ~r"^protocol String\.Chars not implemented for #PID<.+?> of type PID$"
+    message =
+      ~r"^protocol String\.Chars not implemented for type PID\n\nGot value:\n\n    #PID<.+?>$"
 
     assert_raise Protocol.UndefinedError, message, fn ->
       to_string(self())
     end
   end
 
   test "ref" do
-    message = ~r"^protocol String\.Chars not implemented for #Reference<.+?> of type Reference$"
+    message =
+      ~r"^protocol String\.Chars not implemented for type Reference\n\nGot value:\n\n    #Reference<.+?>$"
 
     assert_raise Protocol.UndefinedError, message, fn ->
       to_string(make_ref()) == ""
     end
   end
 
   test "function" do
-    message = ~r"^protocol String\.Chars not implemented for #Function<.+?> of type Function$"
+    message =
+      ~r"^protocol String\.Chars not implemented for type Function\n\nGot value:\n\n    #Function<.+?>$"
 
     assert_raise Protocol.UndefinedError, message, fn ->
       to_string(fn -> nil end)
@@ -146,7 +161,9 @@ defmodule String.Chars.ErrorsTest do
 
   test "port" do
     [port | _] = Port.list()
-    message = ~r"^protocol String\.Chars not implemented for #Port<.+?> of type Port$"
+
+    message =
+      ~r"^protocol String\.Chars not implemented for type Port\n\nGot value:\n\n    #Port<.+?>$"
 
     assert_raise Protocol.UndefinedError, message, fn ->
       to_string(port)
@@ -155,7 +172,7 @@ defmodule String.Chars.ErrorsTest do
 
   test "user-defined struct" do
     message =
-      "protocol String\.Chars not implemented for %String.Chars.ErrorsTest.Foo{foo: \"bar\"} of type String.Chars.ErrorsTest.Foo (a struct)"
+      "protocol String\.Chars not implemented for type String.Chars.ErrorsTest.Foo (a struct)\n\nGot value:\n\n    %String.Chars.ErrorsTest.Foo{foo: \"bar\"}\n"
 
     assert_raise Protocol.UndefinedError, message, fn ->
       to_string(%Foo{})