Fix compiler download for old versions in ARM64 by ChristopherDedominici · Pull Request #8062 · NomicFoundation/hardhat

ChristopherDedominici · 2026-03-13T15:25:55Z

Problem

On ARM64 Linux, Hardhat fails when trying to compile with old Solidity versions (< 0.5.0) because no native ARM64 binary exists for those versions, not in the official releases nor in the community mirror.

Solution

Based on the available versions listed in the solc-linux-arm64-mirror (which is frozen), the fix hardcodes that native ARM64 binaries only exist from version 0.5.0 onward. For older versions on ARM64 Linux, it skips the native download entirely and uses the WASM compiler instead. This applies to all build profiles, since those old versions simply have no native ARM64 binary anywhere.

changeset-bot · 2026-03-13T15:26:02Z

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Copilot

Pull request overview

Adds a regression test suite intended to reproduce and guard against failures when requesting an older solc version on linux-arm64 where no native ARM64 binary exists.

Changes:

Introduces a new linux-arm64 “bug repro” describe block covering isCompilerDownloaded, downloadCompiler, and getCompiler for solc 0.4.24.
Asserts the downloader APIs return false/undefined (and do not throw) when the ARM64 build is unavailable.

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…mpiler-download

ChristopherDedominici · 2026-03-19T11:48:00Z

  public async getCompiler(version: string): Promise<Compiler | undefined> {
    const build = await this.#getCompilerBuild(version);

-    assertHardhatInvariant(


The assertHardhatInvariant was redundant because #getCompilerBuild() (in this file) already guarantees build is never undefined, if the version isn't found, it throws a HardhatError

Copilot

Pull request overview

Updates Hardhat’s Solidity compiler resolution and download flow on Linux ARM64 to correctly handle very old solc versions that have no native ARM64 binaries, ensuring a WASM fallback instead of failing native downloads.

Changes:

Add hasArm64MirrorBuild and an ARM64 mirror threshold (0.5.0) to distinguish mirror-native vs. official-native vs. no-native versions.
Default per-compiler preferWasm to true on ARM64 for versions with no native build anywhere (< 0.5.0), and keep production-default WASM behavior for versions lacking official ARM64 builds.
Update compiler download/get logic to skip native operations for versions without an ARM64 native build, and add tests for the new behavior.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 1 comment.

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File	Description
v-next/hardhat/src/internal/builtin-plugins/solidity/build-system/solc-info.ts	Introduces mirror-range detection (`hasArm64MirrorBuild`) and threshold constant.
v-next/hardhat/src/internal/builtin-plugins/solidity/config.ts	Adjusts ARM64 per-compiler `preferWasm` defaults to force WASM when no native ARM64 build exists.
v-next/hardhat/src/internal/builtin-plugins/solidity/build-system/compiler/index.ts	Filters native downloads on ARM64 to versions with native builds; adds native-availability guard before native `getCompiler`.
v-next/hardhat/src/internal/builtin-plugins/solidity/build-system/compiler/downloader.ts	Removes a now-redundant invariant after centralizing missing-version handling in `#getCompilerBuild`.
v-next/hardhat/test/internal/builtin-plugins/solidity/build-system/solc-info.ts	Adds unit tests for `hasArm64MirrorBuild` range behavior.
v-next/hardhat/test/internal/builtin-plugins/solidity/config.ts	Adds/updates ARM64 config-resolution tests for the new WASM defaulting rules.
v-next/hardhat/test/internal/builtin-plugins/solidity/build-system/compiler/index.ts	Adds an ARM64-only integration test for WASM fallback for `0.4.x`.
v-next/hardhat/test/internal/builtin-plugins/solidity/build-system/compiler/downloader.ts	Adds tests asserting native ARM64 downloader throws for versions missing from the native list.

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Copilot

Pull request overview

Fixes Solidity compiler resolution on Linux ARM64 for very old solc versions (<0.5.0) by avoiding native compiler downloads (which don’t exist) and ensuring WASM is used instead, while preserving existing ARM64 behavior for mirror/official ranges.

Changes:

Add ARM64 mirror threshold logic (FIRST_ARM64_MIRROR_SOLC_VERSION, hasArm64MirrorBuild) and use it when resolving preferWasm defaults.
Skip native compiler list/download and native compiler selection on Linux ARM64 when no native build exists for the requested version(s), falling back to WASM.
Extend test coverage for mirror/official build detection and for ARM64 old-version WASM fallback behavior.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
v-next/hardhat/src/internal/builtin-plugins/solidity/build-system/solc-info.ts	Introduces ARM64 mirror threshold constant and `hasArm64MirrorBuild()` helper.
v-next/hardhat/src/internal/builtin-plugins/solidity/config.ts	Updates per-compiler `preferWasm` defaulting on ARM64 to force WASM for <0.5.0 across profiles.
v-next/hardhat/src/internal/builtin-plugins/solidity/build-system/compiler/index.ts	Adds `hasNativeBuildForPlatform()` and filters native downloads / native compiler selection accordingly.
v-next/hardhat/src/internal/builtin-plugins/solidity/build-system/compiler/downloader.ts	Adjusts behavior for versions missing from the native build list (now consistently throws `INVALID_SOLC_VERSION`).
v-next/hardhat/test/internal/builtin-plugins/solidity/build-system/solc-info.ts	Adds tests for `hasArm64MirrorBuild()` boundaries.
v-next/hardhat/test/internal/builtin-plugins/solidity/config.ts	Adds ARM64-only test for forcing WASM below mirror threshold and updates assertions/comments for mirror-range versions.
v-next/hardhat/test/internal/builtin-plugins/solidity/build-system/compiler/index.ts	Adds unit tests for `hasNativeBuildForPlatform()` and an ARM64-only integration-style fallback test using high-level APIs.

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Copilot

Pull request overview

This PR fixes Hardhat’s Solidity compiler resolution/download behavior on Linux ARM64 for old Solidity versions (<0.5.0) by recognizing that no native ARM64 binaries exist for those versions and automatically falling back to the WASM compiler.

Changes:

Introduce ARM64 mirror range detection (0.5.0–0.8.30) alongside existing “official ARM64 starts at 0.8.31” logic.
Skip native compiler list updates/downloads (and native getCompiler) on Linux ARM64 when a native build cannot exist, ensuring WASM fallback for <0.5.0.
Add/adjust tests to cover mirror detection, config defaulting, downloader behavior for missing versions, and the end-to-end ARM64 WASM fallback.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
v-next/hardhat/src/internal/builtin-plugins/solidity/build-system/solc-info.ts	Adds mirror threshold constant and `hasArm64MirrorBuild()` helper.
v-next/hardhat/src/internal/builtin-plugins/solidity/config.ts	Updates ARM64 per-compiler `preferWasm` defaults to force WASM for `<0.5.0` and keep production behavior for non-official builds.
v-next/hardhat/src/internal/builtin-plugins/solidity/build-system/compiler/index.ts	Adds `hasNativeBuildForPlatform()` and uses it to avoid native download/get attempts for ARM64 `<0.5.0`, enabling WASM fallback.
v-next/hardhat/src/internal/builtin-plugins/solidity/build-system/compiler/downloader.ts	Removes redundant invariant in `getCompiler` now that missing builds throw `INVALID_SOLC_VERSION`.
v-next/hardhat/test/internal/builtin-plugins/solidity/build-system/solc-info.ts	Adds unit tests for `hasArm64MirrorBuild()`.
v-next/hardhat/test/internal/builtin-plugins/solidity/config.ts	Adds ARM64 config-resolution test ensuring `<0.5.0` defaults to `preferWasm: true` across profiles; clarifies default-profile expectations.
v-next/hardhat/test/internal/builtin-plugins/solidity/build-system/compiler/index.ts	Adds tests for `hasNativeBuildForPlatform()` and an ARM64-only integration test verifying WASM fallback; uses mocked global cache dir with cleanup.
v-next/hardhat/test/internal/builtin-plugins/solidity/build-system/compiler/downloader.ts	Adds tests asserting native ARM64 downloader throws `INVALID_SOLC_VERSION` for versions absent from the native build list.

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alcuadrado · 2026-03-19T16:24:53Z

-    );

-    const compiler = await compilerDownloader.getCompiler(version);
+    if (hasNativeBuildForPlatform(version, platform)) {


I like this double-protection here, in case preferWasm: false is wrong used. It also aligns well with "prefer", it's not a strict mandate.

try CI test

9b7c1ae

Copilot AI review requested due to automatic review settings March 13, 2026 15:25

ChristopherDedominici self-assigned this Mar 13, 2026

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ChristopherDedominici added this to Hardhat Mar 13, 2026

github-project-automation Bot moved this to Backlog in Hardhat Mar 13, 2026

ChristopherDedominici moved this from Backlog to In Progress in Hardhat Mar 13, 2026

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ChristopherDedominici added no docs needed This PR doesn't require links to documentation no peer bump needed labels Mar 13, 2026

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ChristopherDedominici added 2 commits March 19, 2026 11:42

fallback to WASM for old ARM64 compilers

01945b0

Merge branch 'main' of github.com:NomicFoundation/hardhat into fix-co…

c1364fb

…mpiler-download

Copilot AI review requested due to automatic review settings March 19, 2026 11:43

ChristopherDedominici commented Mar 19, 2026

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Comment thread v-next/hardhat/test/internal/builtin-plugins/solidity/build-system/compiler/index.ts Outdated

ChristopherDedominici added 2 commits March 19, 2026 12:11

use tmp dir in test

eb529d0

Add tests for hasNativeBuildForPlatform

ef7e280

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Comment thread v-next/hardhat/test/internal/builtin-plugins/solidity/build-system/compiler/index.ts

Comment thread v-next/hardhat/src/internal/builtin-plugins/solidity/build-system/compiler/index.ts Outdated

ChristopherDedominici and others added 2 commits March 19, 2026 13:44

remove mocked dir in test

e6360cb

Potential fix for pull request finding

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Copilot AI review requested due to automatic review settings March 19, 2026 13:45

Create thick-schools-play.md

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ChristopherDedominici marked this pull request as ready for review March 19, 2026 13:48

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ChristopherDedominici added this pull request to the merge queue Mar 19, 2026

Merged via the queue into main with commit a45e689 Mar 19, 2026
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ChristopherDedominici deleted the fix-compiler-download branch March 19, 2026 16:38

github-project-automation Bot moved this from In Review to Done in Hardhat Mar 19, 2026

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Version Packages (v3) #8057

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Fix compiler download for old versions in ARM64#8062

Fix compiler download for old versions in ARM64#8062
ChristopherDedominici merged 8 commits intomainfrom
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