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feat: multi-stmt match arms and block-as-expression

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Blocks can yield a value: last expression statement is the result.
Match arms accept block bodies, so multi-statement arms work:

  match n {
    1 => { let a = 10; a + 1 },
    _ => 0
  }

Bootstrap: lowerBlock(asExpr) lifts the trailing skExpr. Selfhost: parse
{...} as ekBlock, emit __blk_N yield temps (retTypeKind -2), and treat
only non-empty strValue as match/block yield. Nested enum/struct pattern
bindings recurse in both compilers.

Example: match_block.bux. Selfhost-loop remains binary-identical.
This commit is contained in:
dimgigov
2026-07-18 01:24:48 +03:00
parent e3ca724bfa
commit f9185c96b2
8 changed files with 337 additions and 98 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/sema.bux
+49 -27
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@@ -446,10 +446,10 @@ func Sema_BindPattern(sema: *Sema, pat: *Pattern, subject: *Expr) {
var arg: *Pattern = pat.patArgs;
var ai: int = 0;
while arg != null as *Pattern {
var ftype: String = "int";
if ai == 0 { ftype = fieldType0; }
else if ai == 1 { ftype = fieldType1; }
if arg.kind == pkIdent {
var ftype: String = "int";
if ai == 0 { ftype = fieldType0; }
else if ai == 1 { ftype = fieldType1; }
var bsym: Symbol;
Sema_ZeroInitSymbol(&bsym);
bsym.kind = skVar;
@@ -467,6 +467,14 @@ func Sema_BindPattern(sema: *Sema, pat: *Pattern, subject: *Expr) {
bsym.isPublic = false;
bsym.decl = null as *Decl;
discard Scope_Define(sema.scope, bsym);
} else {
// Nested pattern: synthesize a fake subject expr with payload type
let fake: *Expr = bux_alloc(sizeof(Expr)) as *Expr;
let fte: *TypeExpr = bux_alloc(sizeof(TypeExpr)) as *TypeExpr;
fte.kind = tekNamed;
fte.typeName = ftype;
fake.refType = fte;
Sema_BindPattern(sema, arg, fake);
}
arg = arg.patNext;
ai = ai + 1;
@@ -478,19 +486,17 @@ func Sema_BindPattern(sema: *Sema, pat: *Pattern, subject: *Expr) {
var ei: int = 0;
var elem: *Pattern = pat.patArgs;
while elem != null as *Pattern {
if elem.kind == pkIdent {
var ety: String = "int";
// Tuple_int_int → fields are ints by default; prefer subject type args if present
if subject != null as *Expr && subject.refType != null as *TypeExpr {
if subject.refType.kind == tekTuple {
// typeArgName0 / typeArgName1 store element type names when available
if ei == 0 && !String_Eq(subject.refType.typeArgName0, "") {
ety = subject.refType.typeArgName0;
} else if ei == 1 && !String_Eq(subject.refType.typeArgName1, "") {
ety = subject.refType.typeArgName1;
}
var ety: String = "int";
if subject != null as *Expr && subject.refType != null as *TypeExpr {
if subject.refType.kind == tekTuple {
if ei == 0 && !String_Eq(subject.refType.typeArgName0, "") {
ety = subject.refType.typeArgName0;
} else if ei == 1 && !String_Eq(subject.refType.typeArgName1, "") {
ety = subject.refType.typeArgName1;
}
}
}
if elem.kind == pkIdent {
var bsym: Symbol;
Sema_ZeroInitSymbol(&bsym);
bsym.kind = skVar;
@@ -505,6 +511,13 @@ func Sema_BindPattern(sema: *Sema, pat: *Pattern, subject: *Expr) {
bsym.refType = te;
bsym.isMutable = false;
discard Scope_Define(sema.scope, bsym);
} else {
let fake: *Expr = bux_alloc(sizeof(Expr)) as *Expr;
let fte: *TypeExpr = bux_alloc(sizeof(TypeExpr)) as *TypeExpr;
fte.kind = tekNamed;
fte.typeName = ety;
fake.refType = fte;
Sema_BindPattern(sema, elem, fake);
}
elem = elem.patNext;
ei = ei + 1;
@@ -519,23 +532,25 @@ func Sema_BindPattern(sema: *Sema, pat: *Pattern, subject: *Expr) {
}
var field: *Pattern = pat.patArgs;
while field != null as *Pattern {
if field.kind == pkIdent {
var ftype: String = "int";
if !String_Eq(structName, "") {
let ssym: Symbol = Scope_Lookup(sema.scope, structName);
if ssym.decl != null as *Decl && ssym.decl.kind == dkStruct && ssym.decl.fields != null as *StructField {
var fi: int = 0;
while fi < ssym.decl.fieldCount {
let sf: StructField = ssym.decl.fields[fi];
if String_Eq(sf.name, field.patFieldName) {
if sf.refFieldType != null as *TypeExpr && !String_Eq(sf.refFieldType.typeName, "") {
ftype = sf.refFieldType.typeName;
}
var ftype: String = "int";
if !String_Eq(structName, "") {
let ssym: Symbol = Scope_Lookup(sema.scope, structName);
if ssym.decl != null as *Decl && ssym.decl.kind == dkStruct && ssym.decl.fields != null as *StructField {
var fi: int = 0;
while fi < ssym.decl.fieldCount {
let sf: StructField = ssym.decl.fields[fi];
var fname: String = field.patFieldName;
if String_Eq(fname, "") { fname = field.patIdent; }
if String_Eq(sf.name, fname) {
if sf.refFieldType != null as *TypeExpr && !String_Eq(sf.refFieldType.typeName, "") {
ftype = sf.refFieldType.typeName;
}
fi = fi + 1;
}
fi = fi + 1;
}
}
}
if field.kind == pkIdent {
var bsym: Symbol;
Sema_ZeroInitSymbol(&bsym);
bsym.kind = skVar;
@@ -550,6 +565,13 @@ func Sema_BindPattern(sema: *Sema, pat: *Pattern, subject: *Expr) {
bsym.refType = te;
bsym.isMutable = false;
discard Scope_Define(sema.scope, bsym);
} else {
let fake: *Expr = bux_alloc(sizeof(Expr)) as *Expr;
let fte: *TypeExpr = bux_alloc(sizeof(TypeExpr)) as *TypeExpr;
fte.kind = tekNamed;
fte.typeName = ftype;
fake.refType = fte;
Sema_BindPattern(sema, field, fake);
}
field = field.patNext;
}