Hacktoberfest 2026: los issues que los mantenedores marcaron para octubre, abiertos y aptos para principiantes. Explorar issues de Hacktoberfest

Nested f-strings fail when an inner interpolation contains a brace-bearing string literal

Cerrado
  • ¿Algo no está bien?
#1,253 0 comentarios 0 reacciones 0 asignados Ver en GitHub

Los mantenedores suelen responder en 1 día

Nadie ha tomado este issue todavía.

Evaluación

Dificultad
3/5
Tiempo estimado
1-2 días
Aptitud para principiantes
76/100
Tipo de issue
Error
Claridad
Bien especificado
Estado de actividad
Activo
Stack tecnológico
c
Área
compilers

Línea de trabajo

Start in src/lexer.c around the outer interpolation boundary scanner at lines 407–422, then inspect tests/test_fstrings.eigs lines 46–51 for existing coverage. Run the reproducer and controls first. Done means nested f-strings containing brace-bearing ordinary strings parse and print the expected output, while escaped quotes, dictionaries, direct-string cases, and malformed inputs retain their stated behavior.

Escrito por el modelo de indexación a partir del texto del issue.

Descripción

area:runtime-vm bug found-by:code-review

A nested f-string fails to parse when one of its interpolation expressions contains a string literal with a closing brace. The same brace-bearing string works in a single f-string, and nesting works when that brace is removed.

Reproduce

print of f"outer:{f"inner:{"a}b"}"}"

Actual: exit 1, empty stdout. Stderr reports unterminated f-string expression, unterminated string, unterminated f-string, then unexpected '}' after statement (four parse errors).

Expected: exit 0 and outer:inner:a}b\n.

Paired control: change only a}b to abc:

print of f"outer:{f"inner:{"abc"}"}"

This exits 0 and prints outer:inner:abc\n.

The direct brace-bearing-string control also succeeds:

print of f"inner:{"a}b"}"

It exits 0 and prints inner:a}b\n. The defect therefore concerns composition of supported forms, not a proposed new interpolation syntax.

Cause

The outer interpolation boundary scanner skips from a quote to the next unescaped quote, treating the nested f-string as an ordinary string. The quote beginning the nested interpolation's "a}b" literal ends that skip. Its literal } is then exposed to the outer brace-depth counter, which closes the outer expression prematurely.

Boundary scanning must understand nested f-string lexical structure instead of treating every quoted span as an ordinary string.

Relationship to #334/#344

This is a remaining composition case in the class addressed by closed #334 and fixed in #344, rather than a duplicate of their original direct reproducer. The original direct f"{"a}b"}" case passes on current main. tests/test_fstrings.eigs:46–51 tests brace-bearing ordinary strings and simple nested f-strings separately; it does not combine them.

Regression acceptance

  • The reproducer prints exactly outer:inner:a}b\n and both controls keep passing.
  • Cover opening and closing braces in ordinary strings inside nested f-strings.
  • Retain escaped quotes/backslashes, nested dictionary expressions, and the existing direct-string and simple-nesting cases.
  • Verify actual output for valid cases and keep malformed nested strings failing with diagnostics.

This does not duplicate #1244's LSP source-coordinate issue; here a valid program cannot execute at all.

Verification

Confirmed on a fresh default release build of b91768e23c5a874a64e76e4af9ab291e6aa49983, with inherited EIGS_* variables cleared. Each reproducer and paired control was executed; no runtime or test source was changed. This is a current correctness defect, not a proposed v1 language restriction.

Lenguaje dominante
C
Estrellas
3
Forks
7
Merge medio
4 h 15 min
PR fusionados (30 d)
106

Preparar el entorno

Abrir en Codespaces

Inicia el contenedor de desarrollo del proyecto en tu navegador, con tu propia cuenta de GitHub.

Primeros pasos

  1. Lee el issue completo y luego la guía de contribución del proyecto.
  2. Comenta en el issue que vas a ocuparte — evita que dos personas hagan lo mismo.
  3. Haz un fork del repositorio y trabaja en una rama.
  4. Abre un pull request que haga referencia al número del issue.

Más de InauguralSystems/EigenScript

Todos los issues de InauguralSystems/EigenScript

Issues similares

Más issues de C

Recibe los nuevos issues en tu correo

Un resumen breve de issues de GitHub para principiantes.