Avoid invalid syntax for format-spec with quotes for all Python versions

crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/fstring.py

@@ -664,3 +664,45 @@
 
 # Regression test for https://github.com/astral-sh/ruff/issues/14487
 f"aaaaaaaaaaaaaaaaaaaaaaaaaa {10**27} bbbbbbbbbbbbbbbbbbbbbbbbbb ccccccccccccccccccccccccc"
+
+# Quotes reuse
+f"{'a'}"
+
+# 312+, it's okay to change the outer quotes even when there's a debug expression using the same quotes
+f'foo {10 + len("bar")=}'
+f'''foo {10 + len("""bar""")=}'''
+
+# 312+, it's okay to change the quotes here without creating an invalid f-string
+f'{"""other " """}'
+f'{"""other " """ + "more"}'
+f'{b"""other " """}'
+f'{f"""other " """}'
+
+
+# Regression tests for https://github.com/astral-sh/ruff/issues/13935
+f'{1: hy "user"}'
+f'{1:hy "user"}'
+f'{1: abcd "{1}" }'
+f'{1: abcd "{'aa'}" }'
+f'{1=: "abcd {'aa'}}'
+f'{x:a{z:hy "user"}} \'\'\''
+
+# Changing the outer quotes is fine because the format-spec is in a nested expression.
+f'{f'{z=:hy "user"}'} \'\'\''
+
+
+#  We have to be careful about changing the quotes if the f-string has a debug expression because it is inserted verbatim.
+f'{1=: "abcd \'\'}'  # Don't change the outer quotes, or it results in a syntax error
+f'{1=: abcd \'\'}'  # Changing the quotes here is fine because the inner quotes aren't the opposite quotes
+f'{1=: abcd \"\"}'  # Changing the quotes here is fine because the inner quotes are escaped
+# Don't change the quotes in the following cases:
+f'{x=:hy "user"} \'\'\''
+f'{x=:a{y:hy "user"}} \'\'\''
+f'{x=:a{y:{z:hy "user"}}} \'\'\''
+f'{x:a{y=:{z:hy "user"}}} \'\'\''
+
+# This is fine because the debug expression and format spec are in a nested expression
+
+f"""{1=: "this" is fine}"""
+f'''{1=: "this" is fine}'''  # Change quotes to double quotes because they're preferred
+f'{1=: {'ab"cd"'}}'  # It's okay if the quotes are in an expression part.

crates/ruff_python_formatter/src/string/normalize.rs

@@ -60,26 +60,29 @@ impl<'a, 'src> StringNormalizer<'a, 'src> {
                     return QuoteStyle::Preserve;
                 }
 
-                // There are two cases where it's necessary to preserve the quotes
-                // if the target version is pre 3.12 and the part is an f-string.
-                if !self.context.options().target_version().supports_pep_701() {
-                    if let StringLikePart::FString(fstring) = string {
+                if let StringLikePart::FString(fstring) = string {
+                    // There are two cases where it's necessary to preserve the quotes if the
+                    // target version is pre 3.12 and the part is an f-string.
+                    if !self.context.options().target_version().supports_pep_701() {
                         // An f-string expression contains a debug text with a quote character
-                        // because the formatter will emit the debug expression **exactly** the same as in the source text.
+                        // because the formatter will emit the debug expression **exactly** the
+                        // same as in the source text.
                         if is_fstring_with_quoted_debug_expression(fstring, self.context) {
                             return QuoteStyle::Preserve;
                         }
 
-                        // An f-string expression that contains a triple quoted string literal expression
-                        // that contains a quote.
+                        // An f-string expression that contains a triple quoted string literal
+                        // expression that contains a quote.
                         if is_fstring_with_triple_quoted_literal_expression_containing_quotes(
                             fstring,
                             self.context,
                         ) {
                             return QuoteStyle::Preserve;
                         }
                     }
-                } else if let StringLikePart::FString(fstring) = string {
+
+                    // An f-string expression element contains a debug text and the corresponding
+                    // format specifier has a literal element with a quote character.
                     if is_fstring_with_quoted_format_spec_and_debug(fstring, self.context) {
                         return QuoteStyle::Preserve;
                     }

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

@@ -670,6 +670,48 @@ _ = (
 
 # Regression test for https://github.com/astral-sh/ruff/issues/14487
 f"aaaaaaaaaaaaaaaaaaaaaaaaaa {10**27} bbbbbbbbbbbbbbbbbbbbbbbbbb ccccccccccccccccccccccccc"
+
+# Quotes reuse
+f"{'a'}"
+
+# 312+, it's okay to change the outer quotes even when there's a debug expression using the same quotes
+f'foo {10 + len("bar")=}'
+f'''foo {10 + len("""bar""")=}'''
+
+# 312+, it's okay to change the quotes here without creating an invalid f-string
+f'{"""other " """}'
+f'{"""other " """ + "more"}'
+f'{b"""other " """}'
+f'{f"""other " """}'
+
+
+# Regression tests for https://github.com/astral-sh/ruff/issues/13935
+f'{1: hy "user"}'
+f'{1:hy "user"}'
+f'{1: abcd "{1}" }'
+f'{1: abcd "{'aa'}" }'
+f'{1=: "abcd {'aa'}}'
+f'{x:a{z:hy "user"}} \'\'\''
+
+# Changing the outer quotes is fine because the format-spec is in a nested expression.
+f'{f'{z=:hy "user"}'} \'\'\''
+
+
+#  We have to be careful about changing the quotes if the f-string has a debug expression because it is inserted verbatim.
+f'{1=: "abcd \'\'}'  # Don't change the outer quotes, or it results in a syntax error
+f'{1=: abcd \'\'}'  # Changing the quotes here is fine because the inner quotes aren't the opposite quotes
+f'{1=: abcd \"\"}'  # Changing the quotes here is fine because the inner quotes are escaped
+# Don't change the quotes in the following cases:
+f'{x=:hy "user"} \'\'\''
+f'{x=:a{y:hy "user"}} \'\'\''
+f'{x=:a{y:{z:hy "user"}}} \'\'\''
+f'{x:a{y=:{z:hy "user"}}} \'\'\''
+
+# This is fine because the debug expression and format spec are in a nested expression
+
+f"""{1=: "this" is fine}"""
+f'''{1=: "this" is fine}'''  # Change quotes to double quotes because they're preferred
+f'{1=: {'ab"cd"'}}'  # It's okay if the quotes are in an expression part.
 ```
 
 ## Outputs
@@ -1398,6 +1440,48 @@ _ = (
 
 # Regression test for https://github.com/astral-sh/ruff/issues/14487
 f"aaaaaaaaaaaaaaaaaaaaaaaaaa {10**27} bbbbbbbbbbbbbbbbbbbbbbbbbb ccccccccccccccccccccccccc"
+
+# Quotes reuse
+f"{'a'}"
+
+# 312+, it's okay to change the outer quotes even when there's a debug expression using the same quotes
+f'foo {10 + len("bar")=}'
+f'''foo {10 + len("""bar""")=}'''
+
+# 312+, it's okay to change the quotes here without creating an invalid f-string
+f'{"""other " """}'
+f'{"""other " """ + "more"}'
+f'{b"""other " """}'
+f'{f"""other " """}'
+
+
+# Regression tests for https://github.com/astral-sh/ruff/issues/13935
+f'{1: hy "user"}'
+f'{1:hy "user"}'
+f'{1: abcd "{1}" }'
+f'{1: abcd "{"aa"}" }'
+f'{1=: "abcd {'aa'}}'
+f"{x:a{z:hy \"user\"}} '''"
+
+# Changing the outer quotes is fine because the format-spec is in a nested expression.
+f"{f'{z=:hy "user"}'} '''"
+
+
+#  We have to be careful about changing the quotes if the f-string has a debug expression because it is inserted verbatim.
+f'{1=: "abcd \'\'}'  # Don't change the outer quotes, or it results in a syntax error
+f"{1=: abcd \'\'}"  # Changing the quotes here is fine because the inner quotes aren't the opposite quotes
+f"{1=: abcd \"\"}"  # Changing the quotes here is fine because the inner quotes are escaped
+# Don't change the quotes in the following cases:
+f'{x=:hy "user"} \'\'\''
+f'{x=:a{y:hy "user"}} \'\'\''
+f'{x=:a{y:{z:hy "user"}}} \'\'\''
+f'{x:a{y=:{z:hy "user"}}} \'\'\''
+
+# This is fine because the debug expression and format spec are in a nested expression
+
+f"""{1=: "this" is fine}"""
+f"""{1=: "this" is fine}"""  # Change quotes to double quotes because they're preferred
+f'{1=: {'ab"cd"'}}'  # It's okay if the quotes are in an expression part.
 ```
 
 
@@ -2078,6 +2162,48 @@ _ = (
 
 # Regression test for https://github.com/astral-sh/ruff/issues/14487
 f"aaaaaaaaaaaaaaaaaaaaaaaaaa {10**27} bbbbbbbbbbbbbbbbbbbbbbbbbb ccccccccccccccccccccccccc"
+
+# Quotes reuse
+f"{'a'}"
+
+# 312+, it's okay to change the outer quotes even when there's a debug expression using the same quotes
+f'foo {10 + len("bar")=}'
+f'''foo {10 + len("""bar""")=}'''
+
+# 312+, it's okay to change the quotes here without creating an invalid f-string
+f'{"""other " """}'
+f'{"""other " """ + "more"}'
+f'{b"""other " """}'
+f'{f"""other " """}'
+
+
+# Regression tests for https://github.com/astral-sh/ruff/issues/13935
+f'{1: hy "user"}'
+f'{1:hy "user"}'
+f'{1: abcd "{1}" }'
+f'{1: abcd "{'aa'}" }'
+f'{1=: "abcd {'aa'}}'
+f'{x:a{z:hy "user"}} \'\'\''
+
+# Changing the outer quotes is fine because the format-spec is in a nested expression.
+f'{f'{z=:hy "user"}'} \'\'\''
+
+
+#  We have to be careful about changing the quotes if the f-string has a debug expression because it is inserted verbatim.
+f'{1=: "abcd \'\'}'  # Don't change the outer quotes, or it results in a syntax error
+f'{1=: abcd \'\'}'  # Changing the quotes here is fine because the inner quotes aren't the opposite quotes
+f'{1=: abcd \"\"}'  # Changing the quotes here is fine because the inner quotes are escaped
+# Don't change the quotes in the following cases:
+f'{x=:hy "user"} \'\'\''
+f'{x=:a{y:hy "user"}} \'\'\''
+f'{x=:a{y:{z:hy "user"}}} \'\'\''
+f'{x:a{y=:{z:hy "user"}}} \'\'\''
+
+# This is fine because the debug expression and format spec are in a nested expression
+
+f"""{1=: "this" is fine}"""
+f"""{1=: "this" is fine}"""  # Change quotes to double quotes because they're preferred
+f'{1=: {'ab"cd"'}}'  # It's okay if the quotes are in an expression part.
 ```
 
 
@@ -2915,4 +3041,28 @@ f"aaaaaaaaaaaaaaaaaaaaaaaaaa {10**27} bbbbbbbbbbbbbbbbbbbbbbbbbb ccccccccccccccc
  )
 
  # Regression test for https://github.com/astral-sh/ruff/issues/14487
+@@ -678,18 +726,18 @@
+ f'{1: hy "user"}'
+ f'{1:hy "user"}'
+ f'{1: abcd "{1}" }'
+-f'{1: abcd "{'aa'}" }'
++f'{1: abcd "{"aa"}" }'
+ f'{1=: "abcd {'aa'}}'
+-f'{x:a{z:hy "user"}} \'\'\''
++f"{x:a{z:hy \"user\"}} '''"
+
+ # Changing the outer quotes is fine because the format-spec is in a nested expression.
+-f'{f'{z=:hy "user"}'} \'\'\''
++f"{f'{z=:hy "user"}'} '''"
+
+
+ #  We have to be careful about changing the quotes if the f-string has a debug expression because it is inserted verbatim.
+ f'{1=: "abcd \'\'}'  # Don't change the outer quotes, or it results in a syntax error
+-f'{1=: abcd \'\'}'  # Changing the quotes here is fine because the inner quotes aren't the opposite quotes
+-f'{1=: abcd \"\"}'  # Changing the quotes here is fine because the inner quotes are escaped
++f"{1=: abcd \'\'}"  # Changing the quotes here is fine because the inner quotes aren't the opposite quotes
++f"{1=: abcd \"\"}"  # Changing the quotes here is fine because the inner quotes are escaped
+ # Don't change the quotes in the following cases:
+ f'{x=:hy "user"} \'\'\''
+ f'{x=:a{y:hy "user"}} \'\'\''
 ```