ruff F541

• If the f-string is part of a docstring (e.g., immediately follows a function/class definition), removing the 'f' may preserve the docstring but Ruff marks the fix unsafe in such cases—however, if incorrectly applied, it could alter tooling that distinguishes docstrings by presence of 'f'.
• In a line-continued context using backslash (e.g., `f"hello" \ f"world"`), removing the 'f' from one segment changes the type of that segment from f-string to str, potentially breaking concatenation semantics if the other segment relies on interpolation (though rule only fires when no segment has placeholders).
• If the f-string contains escaped quote characters (e.g., `f"He said \"hi\""`), the fix preserves them correctly since they are literal in both f-string and regular string contexts.
• When the f-string uses triple quotes (e.g., `f"""hello"""`), the fix produces a triple-quoted regular string, which behaves identically for content without placeholders or escape dependencies.
• If the f-string is a raw f-string (e.g., `rf"\n"`), the fix removes the 'f' to yield `r"\n"`, preserving raw string behavior; however, if the original relied on f-string-specific raw processing (which doesn't differ from raw string for non-interpolated content), it is safe—but Ruff may still consider it hazardous due to prefix alteration.
• If the f-string appears inside a larger expression where its type is used in overload resolution or isinstance checks (rare), changing it from f-string to str could theoretically affect behavior, though both are instances of str and share the same runtime type.
• If the f-string is adjacent to another string literal without an operator (implicit concatenation) and only the f-string is modified (e.g., `f"hello" "world"` → `"hello" "world"`), the concatenation result remains unchanged as both are string literals.
• If the f-string contains a comment inside (invalid syntax—comments cannot be inside string literals), this is not a concern; however, if the line has a trailing comment (e.g., `f"hi" # note`), the fix preserves the comment as it lies outside the literal.
• If the f-string is generated via a macro or code‑generation tool that expects the 'f' prefix for later processing, removing it could break downstream tooling, though this is outside Python semantics.
• If the f-string is part of a stub file (.pyi) and the fixer runs there, altering the literal may affect type checker expectations, though f-strings without placeholders are uncommon in stubs and behave identically as str.

--- orig.py	2026-10-17 16:53:59.061364670 -0400
+++ fixed.py	2026-10-17 16:53:59.227367318 -0400
@@ -1,6 +1,6 @@
 results = []
 for i in range(3):
-    if (s := f"count") == "count":
+    if (s := "count") == "count":
         results.append(i)
         def make_closure():
             return s

[0, 'count', 1, 'count', 2, 'count']

--- orig.py	2026-10-17 16:53:59.332368993 -0400
+++ fixed.py	2026-10-17 16:53:59.494371576 -0400
@@ -1,4 +1,4 @@
-template = f"Hello"
+template = "Hello"
 value = template % {}
 print(value)
 try:

Hello

--- orig.py	2026-10-17 16:53:59.597373219 -0400
+++ fixed.py	2026-10-17 16:53:59.767375931 -0400
@@ -1,4 +1,4 @@
-data = f"test"
+data = "test"
 with open('tmp.bin', 'wb') as f:
     f.write(data.encode())
 with open('tmp.bin', 'rb') as f:

b'test'

--- orig.py	2026-10-17 16:53:59.868377542 -0400
+++ fixed.py	2026-10-17 16:54:00.042380317 -0400
@@ -1,7 +1,7 @@
 with open('tmp.txt', 'w') as f:
-    f.write(f"first")
+    f.write("first")
 with open('tmp.txt', 'a') as f:
-    f.write(f"second")
+    f.write("second")
 with open('tmp.txt', 'r') as f:
     print(f.read())
 import os

firstsecond

--- orig.py	2026-10-17 16:54:00.150382038 -0400
+++ fixed.py	2026-10-17 16:54:00.312384620 -0400
@@ -1,2 +1,2 @@
-s = f"He said \"hi\""
+s = "He said \"hi\""
 print(s.count('\"'))

2

--- orig.py	2026-10-17 16:54:00.412386213 -0400
+++ fixed.py	2026-10-17 16:54:00.581388907 -0400
@@ -1,4 +1,4 @@
 def process_fstring(src):
     return src.startswith('f') and 'dynamic' in src
-s = f"dynamic"
+s = "dynamic"
 print(process_fstring(s))

False

--- orig.py	2026-10-17 16:54:00.677390437 -0400
+++ fixed.py	2026-10-17 16:54:00.845393114 -0400
@@ -1,5 +1,5 @@
 __all__ = ['VALUE']
-VALUE = f"shared"
+VALUE = "shared"
 def get_value():
     return VALUE
 print(get_value())

shared

--- orig.py	2026-10-17 16:54:06.414481647 -0400
+++ fixed.py	2026-10-17 16:54:06.585484359 -0400
@@ -1,2 +1,2 @@
-s = rf'\n'
+s = r'\n'
 print(repr(s))

'\\n'

--- orig.py	2026-10-17 16:54:06.684485929 -0400
+++ fixed.py	2026-10-17 16:54:07.084492273 -0400
@@ -5,5 +5,5 @@
         self.buf.append(data)
 log = Logger()
 with log:
-    log.write(f'hello')
+    log.write('hello')
 print(''.join(log.buf))

--- orig.py	2026-10-17 16:54:07.310495855 -0400
+++ fixed.py	2026-10-17 16:54:07.477498502 -0400
@@ -1,6 +1,6 @@
-open('tmp.txt', 'w').write(f'first')
+open('tmp.txt', 'w').write('first')
 with open('tmp.txt', 'r+') as f:
-    f.write(f'second')
+    f.write('second')
     f.truncate()
 with open('tmp.txt') as f:
     print(f.read())

second

[1]

1.23

This is a docstring