Disallow newlines in format specifiers of single quoted f- or t-strings (#18708)

crates/ruff_python_formatter/tests/fixtures.rs

@@ -324,7 +324,12 @@ fn format_file(source: &str, options: &PyFormatOptions, input_path: &Path) -> St
 
         (Cow::Owned(without_markers), content)
     } else {
-        let printed = format_module_source(source, options.clone()).expect("Formatting to succeed");
+        let printed = format_module_source(source, options.clone()).unwrap_or_else(|err| {
+            panic!(
+                "Formatting `{input_path} was expected to succeed but it failed: {err}",
+                input_path = input_path.display()
+            )
+        });
         let formatted_code = printed.into_code();
 
         ensure_stability_when_formatting_twice(&formatted_code, options, input_path);

crates/ruff_python_formatter/tests/snapshots/black_compatibility@cases__pep_701.py.snap

@@ -81,8 +81,7 @@ x = f"a{2+2:=^{foo(x+y**2):something else}one more}b"
 f'{(abc:=10)}'
 
 f"This is a really long string, but just make sure that you reflow fstrings {
-    2+2:d
-}"
+    2+2:d}"
 f"This is a really long string, but just make sure that you reflow fstrings correctly {2+2:d}"
 
 f"{2+2=}"

crates/ruff_python_formatter/tests/snapshots/format@expression__fstring.py.snap

@@ -284,16 +284,7 @@ x = f"aaaaaaaaa { x   = !r  }"
 
 # Combine conversion flags with format specifiers
 x = f"{x   =   !s
-         :>0
-
-         }"
-# This is interesting. There can be a comment after the format specifier but only if it's
-# on it's own line. Refer to https://github.com/astral-sh/ruff/pull/7787 for more details.
-# We'll format is as trailing comments.
-x = f"{x  !s
-         :>0
-         # comment 21
-         }"
+         :>0}"
 
 x = f"{
     x!s:>{
@@ -301,6 +292,13 @@ x = f"{
         # comment 21-2
     }}"
 
+f"{1
+    # comment 21-3
+:}"
+
+f"{1 # comment 21-4
+:} a"
+
 
 x = f"""
 {              # comment 22
@@ -317,14 +315,14 @@ x = f"""{"foo " +    # comment 24
         """
 
 # Mix of various features.
-f"{  # comment 26
+f"""{  # comment 26
     foo # after foo
    :>{
           x # after x
           }
     # comment 27
     # comment 28
-} woah {x}"
+} woah {x}"""
 
 
 f"""{foo
@@ -338,8 +336,7 @@ f"""{foo
 f"{
     # comment 31
     foo
-   :>
-}"
+   :>}"
 
 # Assignment statement
 
@@ -493,13 +490,11 @@ aaaaa[aaaaaaaaaaa] = (
 
 # This is not a multiline f-string even though it has a newline after the format specifier.
 aaaaaaaaaaaaaaaaaa = f"testeeeeeeeeeeeeeeeeeeeeeeeee{
-    a:.3f
-    }moreeeeeeeeeeeeeeeeeetest"  # comment
+    a:.3f}moreeeeeeeeeeeeeeeeeetest"  # comment
 
 aaaaaaaaaaaaaaaaaa = (
     f"testeeeeeeeeeeeeeeeeeeeeeeeee{
-    a:.3f
-    }moreeeeeeeeeeeeeeeeeetest"  # comment
+    a:.3f}moreeeeeeeeeeeeeeeeeetest"  # comment
 )
 
 # The newline is only considered when it's a tripled-quoted f-string.
@@ -1071,13 +1066,6 @@ x = f"aaaaaaaaa { x   = !r}"
 
 # Combine conversion flags with format specifiers
 x = f"{x   =   !s:>0}"
-# This is interesting. There can be a comment after the format specifier but only if it's
-# on it's own line. Refer to https://github.com/astral-sh/ruff/pull/7787 for more details.
-# We'll format is as trailing comments.
-x = f"{
-    x!s:>0
-    # comment 21
-}"
 
 x = f"{
     x!s:>{
@@ -1085,6 +1073,15 @@ x = f"{
         # comment 21-2
     }}"
 
+f"{
+    1
+    # comment 21-3
+    :}"
+
+f"{
+    1  # comment 21-4
+    :} a"
+
 
 x = f"""
 {              # comment 22
@@ -1102,13 +1099,14 @@ x = f"""{
         """
 
 # Mix of various features.
-f"{  # comment 26
-    foo:>{  # after foo
+f"""{  # comment 26
+    foo  # after foo
+    :>{
         x  # after x
     }
     # comment 27
     # comment 28
-} woah {x}"
+} woah {x}"""
 
 
 f"""{
@@ -1895,13 +1893,6 @@ x = f"aaaaaaaaa { x   = !r}"
 
 # Combine conversion flags with format specifiers
 x = f"{x   =   !s:>0}"
-# This is interesting. There can be a comment after the format specifier but only if it's
-# on it's own line. Refer to https://github.com/astral-sh/ruff/pull/7787 for more details.
-# We'll format is as trailing comments.
-x = f"{
-    x!s:>0
-    # comment 21
-}"
 
 x = f"{
     x!s:>{
@@ -1909,6 +1900,15 @@ x = f"{
         # comment 21-2
     }}"
 
+f"{
+    1
+    # comment 21-3
+    :}"
+
+f"{
+    1  # comment 21-4
+    :} a"
+
 
 x = f"""
 {              # comment 22
@@ -1926,13 +1926,14 @@ x = f"""{
         """
 
 # Mix of various features.
-f"{  # comment 26
-    foo:>{  # after foo
+f"""{  # comment 26
+    foo  # after foo
+    :>{
         x  # after x
     }
     # comment 27
     # comment 28
-} woah {x}"
+} woah {x}"""
 
 
 f"""{

crates/ruff_python_formatter/tests/snapshots/format@expression__tstring.py.snap

@@ -280,16 +280,7 @@ x = t"aaaaaaaaa { x   = !r  }"
 
 # Combine conversion flags with format specifiers
 x = t"{x   =   !s
-         :>0
-
-         }"
-# This is interesting. There can be a comment after the format specifier but only if it's
-# on it's own line. Refer to https://github.com/astral-sh/ruff/pull/7787 for more details.
-# We'll format is as trailing comments.
-x = t"{x  !s
-         :>0
-         # comment 21
-         }"
+         :>0}"
 
 x = f"{
     x!s:>{
@@ -297,6 +288,13 @@ x = f"{
         # comment 21-2
     }}"
 
+f"{1
+    # comment 21-3
+:}"
+
+f"{1 # comment 21-4
+:} a"
+
 x = t"""
 {              # comment 22
  x =   :.0{y # comment 23
@@ -312,14 +310,14 @@ x = t"""{"foo " +    # comment 24
         """
 
 # Mix of various features.
-t"{  # comment 26
+t"""{  # comment 26
     foo # after foo
    :>{
           x # after x
           }
     # comment 27
     # comment 28
-} woah {x}"
+} woah {x}"""
 
 # Assignment statement
 
@@ -473,13 +471,11 @@ aaaaa[aaaaaaaaaaa] = (
 
 # This is not a multiline t-string even though it has a newline after the format specifier.
 aaaaaaaaaaaaaaaaaa = t"testeeeeeeeeeeeeeeeeeeeeeeeee{
-    a:.3f
-    }moreeeeeeeeeeeeeeeeeetest"  # comment
+    a:.3f}moreeeeeeeeeeeeeeeeeetest"  # comment
 
 aaaaaaaaaaaaaaaaaa = (
     t"testeeeeeeeeeeeeeeeeeeeeeeeee{
-    a:.3f
-    }moreeeeeeeeeeeeeeeeeetest"  # comment
+    a:.3f}moreeeeeeeeeeeeeeeeeetest"  # comment
 )
 
 # The newline is only considered when it's a tripled-quoted t-string.
@@ -1045,13 +1041,6 @@ x = t"aaaaaaaaa { x   = !r}"
 
 # Combine conversion flags with format specifiers
 x = t"{x   =   !s:>0}"
-# This is interesting. There can be a comment after the format specifier but only if it's
-# on it's own line. Refer to https://github.com/astral-sh/ruff/pull/7787 for more details.
-# We'll format is as trailing comments.
-x = t"{
-    x!s:>0
-    # comment 21
-}"
 
 x = f"{
     x!s:>{
@@ -1059,6 +1048,15 @@ x = f"{
         # comment 21-2
     }}"
 
+f"{
+    1
+    # comment 21-3
+    :}"
+
+f"{
+    1  # comment 21-4
+    :} a"
+
 x = t"""
 {              # comment 22
  x =   :.0{y # comment 23
@@ -1075,13 +1073,14 @@ x = t"""{
         """
 
 # Mix of various features.
-t"{  # comment 26
-    foo:>{  # after foo
+t"""{  # comment 26
+    foo  # after foo
+    :>{
         x  # after x
     }
     # comment 27
     # comment 28
-} woah {x}"
+} woah {x}"""
 
 # Assignment statement