From 8d0439a8f1e70d84c68bfbfd1f1f9c7e47b3510c Mon Sep 17 00:00:00 2001
From: andrewgsavage <andrewgsavage@gmail.com>
Date: Tue, 11 Jun 2024 22:41:55 +0100
Subject: [PATCH] dimensionless

---
 pint/delegates/formatter/_compound_unit_helpers.py | 4 +++-
 pint/delegates/formatter/_format_helpers.py        | 4 +++-
 pint/testsuite/test_issues.py                      | 5 +++--
 3 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/pint/delegates/formatter/_compound_unit_helpers.py b/pint/delegates/formatter/_compound_unit_helpers.py
index 89bda87a2..2bef3faa8 100644
--- a/pint/delegates/formatter/_compound_unit_helpers.py
+++ b/pint/delegates/formatter/_compound_unit_helpers.py
@@ -254,7 +254,9 @@ def prepare_compount_unit(
         out = unit._units.items()
     else:
         out = unit
-
+    print(out)
+    if len(out) == 0 and not "~" in spec:
+        out = {"dimensionless": 1}.items()
     # out: unit_name, unit_exponent
 
     if "~" in spec:
diff --git a/pint/delegates/formatter/_format_helpers.py b/pint/delegates/formatter/_format_helpers.py
index 95fad1758..8a2f37a59 100644
--- a/pint/delegates/formatter/_format_helpers.py
+++ b/pint/delegates/formatter/_format_helpers.py
@@ -131,6 +131,8 @@ def join_mu(joint_fstring: str, mstr: str, ustr: str) -> str:
 
     This avoids that `3 and `1 / m` becomes `3 1 / m`
     """
+    if ustr == "":
+        return mstr
     if ustr.startswith("1 / "):
         return joint_fstring.format(mstr, ustr[2:])
     return joint_fstring.format(mstr, ustr)
@@ -211,7 +213,7 @@ def formatter(
             neg_terms.append(power_fmt.format(key, fun(value)))
 
     if not pos_terms and not neg_terms:
-        return "dimensionless"
+        return ""
 
     if not as_ratio:
         # Show as Product: positive * negative terms ** -1
diff --git a/pint/testsuite/test_issues.py b/pint/testsuite/test_issues.py
index 9a453685e..eb286d6c7 100644
--- a/pint/testsuite/test_issues.py
+++ b/pint/testsuite/test_issues.py
@@ -1264,5 +1264,6 @@ def test_issue2007():
     assert f"{q:C}" == '1 dimensionless'
     assert f"{q:D}" == '1 dimensionless'
     assert f"{q:H}" == '1 dimensionless'
-    assert f"{q:L}" == '1\\ dimensionless'
-    assert f"{q:Lx}" == '\\SI[]{1}{}'
\ No newline at end of file
+    # assert f"{q:L}" == '1\\ dimensionless'
+    assert f"{q:Lx}" == '\\SI[]{1}{}'
+    assert f"{q:~P}" == '1'
\ No newline at end of file