Write a positional construction as a Go composite literal (closes #68) [patch]

[matt-edmondson]

Fixes #68.

What was wrong

GoGenerator.GenerateConstructionExpression parted its three shapes on whether any argument was a MemberInitialiser. That conflates the two things a type followed by values can be in Go:

• a conversion, int64(n) — which takes exactly one operand, and
• a positional composite literal, Point{1, 2} — which lists a struct's fields in declaration order.

So a ConstructionExpression with a type and two plain arguments came out as Wrapper(1, 2), which Go rejects with too many arguments in conversion to Wrapper. It is not a longer conversion; there is no such thing.

The change

Coder/Languages/GoGenerator.cs — route to the brace list whenever the argument count is not exactly one, and reserve the parenthesised form for the single operand that genuinely is a conversion. The single-argument loop collapses to one write now that it can only ever run once. The <remarks> says why the count is what parts the two, since the old text explained the shapes but not the boundary.

Nothing else moves: an empty construction is still Point{}, one naming its members is still Point{X: 1}, one with no type at all is still the bare list the declaration around it types, and int64(n) is untouched.

Tests

Both are new, and both fail on main:

• GoGeneratorTests.Construction_IsAConversionOnlyWhereItTakesOneValue pins all four shapes in one place. Without the fix: Assert.AreEqual("Wrapper{1, 2}", …) — got Wrapper(1, 2).
• GoGeneratedSourceCompilesTests grows a Corner field built positionally, used by the driver. This is the shape the exemplar had no case for — the table lists its members by name and the static_assert equivalent constructs nothing — so a real toolchain now checks it. Without the fix: ./exemplar.go:89:29: too many arguments in conversion to Point.

Verified by reverting the generator change, rebuilding, and watching both tests fail with exactly those messages, then restoring it.

Full suite: 858 passed, 0 failed (net10.0, with a Go toolchain on the path so the compile and gofmt checks ran rather than reporting inconclusive).

🤖 Generated with Claude Code

https://claude.ai/code/session_013HjQ6mUh5eNFYPYWU3GpD2

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Generated by Claude Code

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

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