Avoid invalid syntax for format-spec with quotes for all Python versi…

…ons (#14625)

## Summary

fixes: #14608

The logic that was only applied for 3.12+ target version needs to be
applied for other versions as well.

## Test Plan

I've moved the existing test cases for 3.12 only to `f_string.py` so
that it's tested against the default target version.

I think we should probably enabled testing for two target version (pre
3.12 and 3.12) but it won't highlight any issue because the parser
doesn't consider this. Maybe we should enable this once we have target
version specific syntax errors in place
(#6591).

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"}} \'\'\''
 ```