lib: add Math.sumPrecise type definition (ES2025)

[kamalkarki111]

Summary

Adds type definition for Math.sumPrecise which is part of the TC39 proposal-math-sum that reached Stage 4 on 2025-07-28, making it part of ES2026.

Changes

• New file: src/lib/esnext.math.d.ts — extends interface Math with sumPrecise
• Updated src/lib/esnext.d.ts — added /// <reference lib="esnext.math" />
• Updated src/lib/libs.json — registered esnext.math in the libs array
• Updated src/compiler/commandLineParser.ts — mapped esnext.math lib name to file
• Updated src/compiler/utilities.ts — added sumPrecise to ScriptTargetFeatures for helpful diagnostics

Why esnext, not es2025?

The proposal reached Stage 4 on 2025-07-28, one month after ES2025 was finalized (June 2025), so it will be included in ES2026. TypeScript does not have es2026 lib files yet, so esnext is the correct placement for now.

References

• TC39 Proposal: https://github.com/tc39/proposal-math-sum
• Stage 4 meeting notes: https://github.com/tc39/notes/blob/main/meetings/2025-07/july-28.md#mathsumprecise-for-stage-4
• MDN: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/sumPrecise

Same changes as #63429 (recreated via GitHub MCP).

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[Copilot]

Pull request overview

Adds an esnext lib definition for the Stage 4 Math.sumPrecise API and wires it into TypeScript’s lib selection pipeline (--lib//// <reference lib=... />), along with conformance coverage and updated baselines.

Changes:

• Added new lib file esnext.math defining Math.sumPrecise(numbers: Iterable<number>): number.
• Registered esnext.math as a selectable lib and included it from esnext.
• Added a conformance test plus updated reference/config baselines (notably TS6046’s allowed --lib list).

Reviewed changes

Copilot reviewed 14 out of 19 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/lib/esnext.math.d.ts	Introduces the Math.sumPrecise type definition under an esnext by-feature lib.
src/lib/esnext.d.ts	Ensures --lib esnext also brings in esnext.math.
src/lib/libs.json	Registers esnext.math in the library registry used by the build/tooling.
src/compiler/commandLineParser.ts	Maps esnext.math to lib.esnext.math.d.ts for --lib parsing/resolution.
src/compiler/utilities.ts	Adds sumPrecise to ScriptTargetFeatures for improved “missing lib” diagnostics.
tests/cases/conformance/esnext/mathSumPrecise.ts	Adds a conformance test validating the new lib surface area and type errors.
tests/baselines/reference/mathSumPrecise.types	New types baseline for the conformance test.
tests/baselines/reference/mathSumPrecise.symbols	New symbols baseline for the conformance test.
tests/baselines/reference/config/convertCompilerOptionsFromJson/Convert trailing-whitespace string option of libs to compiler-options with jsonSourceFile api.js	Updates TS6046 allowed-lib list to include esnext.math.
tests/baselines/reference/config/convertCompilerOptionsFromJson/Convert trailing-whitespace string option of libs to compiler-options with json api.js	Same TS6046 allowed-lib list update.
tests/baselines/reference/config/convertCompilerOptionsFromJson/Convert incorrect option of libs to compiler-options with jsonSourceFile api.js	Same TS6046 allowed-lib list update.
tests/baselines/reference/config/convertCompilerOptionsFromJson/Convert incorrect option of libs to compiler-options with json api.js	Same TS6046 allowed-lib list update.
tests/baselines/reference/config/convertCompilerOptionsFromJson/Convert empty string option of libs to compiler-options with jsonSourceFile api.js	Same TS6046 allowed-lib list update.
tests/baselines/reference/config/convertCompilerOptionsFromJson/Convert empty string option of libs to compiler-options with json api.js	Same TS6046 allowed-lib list update.
tests/baselines/reference/config/convertCompilerOptionsFromJson/Convert empty string option of libs array to compiler-options with jsonSourceFile api.js	Same TS6046 allowed-lib list update.
tests/baselines/reference/config/convertCompilerOptionsFromJson/Convert empty string option of libs array to compiler-options with json api.js	Same TS6046 allowed-lib list update.
tests/baselines/reference/config/commandLineParsing/parseCommandLine/Parse invalid option of library flags.js	Updates TS6046 allowed-lib list to include esnext.math.
tests/baselines/reference/config/commandLineParsing/parseCommandLine/Parse --lib option with trailing white-space.js	Same TS6046 allowed-lib list update.
tests/baselines/reference/config/commandLineParsing/parseCommandLine/Parse --lib option with extra comma.js	Same TS6046 allowed-lib list update.

Files not reviewed (3)

• tests/baselines/reference/config/commandLineParsing/parseCommandLine/Parse --lib option with extra comma.js: Generated file
• tests/baselines/reference/config/commandLineParsing/parseCommandLine/Parse --lib option with trailing white-space.js: Generated file
• tests/baselines/reference/config/commandLineParsing/parseCommandLine/Parse invalid option of library flags.js: Generated file