`as`/`satisfies` between exponentiation operators cannot be safely erased

[magic-akari]

🔎 Search Terms

• as exponentiation precedence
• satisfies exponentiation
• erasableSyntaxOnly
• blank-space erasure
• right associativity
• erasableSyntaxOnly should error on unerasable as/satisfies #63527
• Design Meeting Notes, 2026-06-04 #63533

🕗 Version & Regression Information

• This occurs in TypeScript 7.0.2 from typescript-go at 2bd066d87f5bafd315be9f40889d0a60b9e58e0b.
• This was tested after Stop parsing constructs that make it impossible to erase as/satisfies typescript-go#4192 with erasableSyntaxOnly enabled.
• I reviewed erasableSyntaxOnly should error on unerasable as/satisfies #63527 and Design Meeting Notes, 2026-06-04 #63533.

⏯ Playground Link

https://www.typescriptlang.org/play/?erasableSyntaxOnly=true#code/PTAEAEFMCcEMGdYCMA2kDKBPAdgF1gB4Dy2KmAXKLtAK6QBQ9AxgPbby6gIBqsKdoALygATKABU40AGYu8UNhoBbJDAlSRAbmZsOoRLgCW8AGaHI8Xv0hDR6mfthHT5+YpVrJozUA

💻 Code

const asValue = 2 ** 3 as number ** 2;
const satisfiesValue = 2 ** 3 satisfies number ** 2;

🙁 Actual behavior

Both expressions are accepted without a diagnostic.

TypeScript emits each expression with the left-hand exponentiation parenthesized:

const asValue = (2 ** 3) ** 2;
const satisfiesValue = (2 ** 3) ** 2;

Replacing only the type syntax with spaces instead produces the equivalent of:

const asValue = 2 ** (3 ** 2);
const satisfiesValue = 2 ** (3 ** 2);

The emitted expression evaluates to 64, while the blanked expression evaluates to 512.

🙂 Expected behavior

TypeScript should report an error for these expressions because erasing the type syntax without moving source positions changes the exponentiation grouping. This should apply to both as and satisfies, consistent with the conclusion of #63527.

Additional information about the issue

Exponentiation is right-associative. The two ** operators have equal precedence, but removing the intervening type syntax changes the expression from left-grouped to right-grouped.

Related:

• erasableSyntaxOnly should error on unerasable as/satisfies #63527
• Design Meeting Notes, 2026-06-04 #63533
• Stop parsing constructs that make it impossible to erase as/satisfies typescript-go#4192