[nebasuke]

Claude summary

Slang stack traces end to end, and the Solidity version passed the way slang now expects it. EDR builds slang stack traces from two compiler outputs, the DWARF debugInfo the plugin already requests and the per-source debugSymbols table (NomicFoundation/solx#786), which stands in for the solc AST. This adds the second one, and pins the first slang prerelease that emits everything EDR reads.

Commits

1. feat: augmentIfSlang adds debugSymbols to the file-level ["*"][""] selectors, next to ast, so it reaches the solcInput and the build-id hash like the other defaults. addSlangDebugInfoSelectors becomes addSlangStackTraceSelectors, since it now covers both outputs.
2. test: builds the with-debug-info fixture with the slang profile, reverts in Counter._checkPositive over a network connection, and checks the error stack names the Solidity frames. It needs a release that emits debugSymbols and an EDR that reads them, so it is gated on HARDHAT_SLANG_EXPECT_STACK_TRACES, like the debugInfo test.
3. feat: augmentIfSlang sets settings.solidityVersion to the entry's version. slang reads the version from standard JSON since feat(slang): add a Solidity version setting solx#787 and rejects --solidity-version next to --standard-json ("Solidity version must be passed via standard JSON input."). In the solcInput, a build info reproduces its compile on its own and the build id tells two versions apart. targetVersionFlag on the release row and targetSolidityVersion on SlangCompiler go, with their three tests. The prerelease pinned at this point ignores the key; commit 4 pins one that reads it.
4. feat: pins 0.1.0-pre.2026-10-14, solx prerelease 5e6ec5e1 (slang v0.2.0, Solidity 0.8.0 to 0.8.37), which carries Use custom error for http provider errors #767, Update Buidler EVM to support solc >= 0.6.9 #702, add buidler-log-remover to plugin list #786 and Improvements of multi-solc implementation #787. Its binaries are published as slang-*, so the platform asset prefix follows. The debugInfo test loses its opt-in now that the pin emits it, and runs like hardhat-slang-solx's real-binary test. A new test compiles Counter.sol through the plugin at its entry's version, then reruns the same input at 0.8.20, which slang must refuse for ^0.8.34.
5. test: an override entry gets the solidityVersion of its own version, not the profile's.
6. feat: a user settings.solidityVersion that differs from the entry's version is a config error at that setting's path. Hardhat picks the entry by matching pragmas against version, so a different value would compile a language version Hardhat didn't choose; until now the plugin overwrote it silently. An equal value is accepted. Entries with their own binary (path) are checked too.
7. perf: SlangCompiler.compile leaves ast out of the selection it hands the binary. Hardhat requests it from every compiler, but slang's AST isn't the solc AST any consumer reads (EDR uses debugSymbols; the EIP-712 collector skips non-solc ASTs). On OpenZeppelin it is 60 of the 77 MB slang returns, and dropping it takes a local cold compile from 18.0 s to 14.3 s. It is dropped at compile time because Hardhat appends its default selection when building the job's input and the hook that could change that is deprecated, so the build info's input still lists ast while its output has none.
8. docs: the README no longer tells users to leave settings.solidityVersion unset; commit 6's validation error says so where it matters.

What it takes to turn on

Piece	Where	Status
debugSymbols output	NomicFoundation/solx#786	merged
slang release with #767 (DWARF), #702 (ABI), #786 and #787	solx prerelease 5e6ec5e1	pinned by commit 4
EDR reading compilerType: "slang" build infos	NomicFoundation/edr#1811	merged, not yet released (latest EDR is 0.23.0)
Hardhat's @nomicfoundation/edr bump	packages/hardhat	after the EDR release
hardhat-slang's peerDependencies.hardhat floor, ^3.15.0 today	packages/hardhat-slang	raise to the first Hardhat release with that bump

Until the EDR bump, a slang build info breaks every network connection, not just stack traces: EDR 0.23.0 does not know "slang" and falls back to the solc path. This is already the case on main (network.connect() throws Failed to parse build info: missing field 'abi'); with this PR the error names ast instead, so merging it ahead of the bump changes no working setup. On EDR 0.22.0, Solidity tests still ran and printed the error as a stack-trace warning.

Verification

Local run with the pinned release downloaded by the plugin, and EDR#1811 at 0438a27dc (napi build linked into packages/hardhat):

Setup	hardhat test solidity	network revert
EDR 0.22.0	Stack Trace Warning: Failed to process AST	network.connect() throws Failed to process AST
EDR#1811	Counter._checkPositive (contracts/Counter.sol:13) ← Counter.set (contracts/Counter.sol:8) ← CounterTest.testSetZeroReverts (contracts/Counter.t.sol:9)	SolidityError with the same two Counter frames

The Solidity-test row used a throwaway Counter.t.sol in the with-debug-info fixture.

• pnpm test in packages/hardhat-slang: 121 pass. Each new test was seen failing first:
  • the selector tests (5) fail without commit 1's change, and the multi-version config test without commit 3's;
  • commit 4's compile test fails on the previous pin, where every slang compile has failed since commit 1 (unknown variant debugSymbols). Run directly, that binary compiles ^0.8.34 at 0.8.20, which is what the test's last assertion rules out;
  • commit 5's test fails without the solidityVersion line in augmentIfSlang, and commit 6's two rejection tests without its check;
  • commit 7's test fails on the previous compile, which forwarded the input unchanged.
• The gated stack-trace test passes with HARDHAT_SLANG_EXPECT_STACK_TRACES=true against EDR#1811, and fails on EDR 0.22.0.
• HARDHAT_RUN_MIRROR_TESTS=true: every asset and checksum of the new pin is served.
• The gated stack-trace test still passes against EDR#1811 after commit 7, with no AST in the build info.
• After EDR#1811 merged: on this branch merged with main (a90e19617), the gated stack-trace test passes with an napi build of EDR main 1da28b28a and fails on Hardhat's EDR 0.23.0. With the pinned release, every source gets a debugSymbols table, including pragma-only, free-function-only and interface-only files, so EDR's new error for a source without one does not fire on plugin output.
• pnpm lint and pnpm build clean.

Notes for review

• 5e6ec5e1's release name ends in debug-fast; the plugin only uses it as the asset suffix.
• The real-binary tests download the ~100 MB release unless HARDHAT_DISABLE_SLOW_TESTS is set.

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[marianfe]

lgtm with one minor comment , thanks!