Files
sx/examples/0038-basic-dead-code-after-terminator.sx
agra 83ec2536af lang: catch/onfail error bindings take parens
try foo() catch (e) { }   // legal
try foo() catch e { }     // parse error with a migration hint

Same capture style as the for-loop. All four catch shapes keep working
with the parenthesized binding — block, bare-expression body, and the
== match sugar — and the no-binding forms are unchanged. onfail follows
the same rule (onfail (e) { }); its expression-cleanup form is
disambiguated by the paren-group-before-brace lookahead, so
onfail (f()); stays an expression cleanup.

AST unchanged; the printer renders the parens; the #run escape help
text updated. Corpus migrated (57 catch + 3 onfail bindings, in-source
parser test strings, specs incl. grammar rules, readme untouched —
no catch examples there).

Regression: examples/1157-diagnostics-catch-binding-needs-parens.sx;
re-captured stderr for 1010/1013/1037/1123 (migrated source echoed in
carets + help text).
2026-06-10 23:05:02 +03:00

35 lines
1.5 KiB
Plaintext

// Dead statements after a block-terminating statement (`return` / `raise`) are
// dropped instead of being emitted into the already-closed basic block.
// Regression (issue 0061): a bare `return X;` / `raise` mid-block closed the
// LLVM basic block but lowering kept emitting the trailing statements into it
// → "Terminator found in the middle of a basic block". The canonical failable
// closure form `{ raise error.X; return x; }` tripped this, blocking ERR E5.1.
//
// The fix must NOT over-reach: a CONDITIONAL `if cond { return }` (and the
// `inline if` pack form) leaves a fresh merge block, so its trailing statements
// must still run — exercised by `clamp` / `pick` below.
#import "modules/std.sx";
E :: error { Neg }
// dead `return 99;` after an unconditional return
const_one :: () -> s64 { return 1; return 99; }
// dead `return x;` after an unconditional raise (the failable closure shape)
always_raise :: (x: s64) -> (s64, !E) { raise error.Neg; return x; }
// guard: a conditional return must still fall through to the trailing return
clamp :: (x: s64) -> s64 { if x > 10 { return 10; } return x; }
main :: () -> s32 {
print("const_one={}\n", const_one()); // 1
print("raised={}\n", always_raise(5) catch (e) 0); // 0
print("clamp_hi={}\n", clamp(42)); // 10
print("clamp_lo={}\n", clamp(7)); // 7
// dead code after a `return` at main's own block level is dropped.
return 0;
print("unreachable\n")
}