internal/shader: Bug fix: Treat multiple constant definitions in one statement correctly

Updates #1192

internal/shader/expr.go

@@ -393,8 +393,9 @@ func (cs *compileState) parseExpr(block *block, expr ast.Expr, markLocalVariable
 		if c, ok := block.findConstant(e.Name); ok {
 			return []shaderir.Expr{
 				{
-					Type:  shaderir.NumberExpr,
-					Const: c.value,
+					Type:      shaderir.NumberExpr,
+					Const:     c.value,
+					ConstType: c.ctyp,
 				},
 			}, []shaderir.Type{c.typ}, nil, true
 		}

internal/shader/shader.go

@@ -33,6 +33,7 @@ type variable struct {
 type constant struct {
 	name  string
 	typ   shaderir.Type
+	ctyp  shaderir.ConstType
 	value gconstant.Value
 }
 
@@ -581,7 +582,7 @@ func (s *compileState) parseConstant(block *block, vs *ast.ValueSpec) ([]constan
 			}
 		}
 
-		es, _, ss, ok := s.parseExpr(block, vs.Values[i], false)
+		es, ts, ss, ok := s.parseExpr(block, vs.Values[i], false)
 		if !ok {
 			return nil, false
 		}
@@ -589,7 +590,7 @@ func (s *compileState) parseConstant(block *block, vs *ast.ValueSpec) ([]constan
 			s.addError(vs.Pos(), fmt.Sprintf("invalid constant expression: %s", name))
 			return nil, false
 		}
-		if len(es) != 1 {
+		if len(ts) != 1 || len(es) != 1 {
 			s.addError(vs.Pos(), fmt.Sprintf("invalid constant expression: %s", n))
 			return nil, false
 		}
@@ -600,6 +601,7 @@ func (s *compileState) parseConstant(block *block, vs *ast.ValueSpec) ([]constan
 		cs = append(cs, constant{
 			name:  name,
 			typ:   t,
+			ctyp:  es[0].ConstType,
 			value: es[0].Const,
 		})
 	}

internal/shader/stmt.go

@@ -520,7 +520,11 @@ func (cs *compileState) assign(block *block, fname string, pos token.Pos, lhs, r
 					return nil, false
 				}
 
-				block.addNamedLocalVariable(name, ts[0], e.Pos())
+				t := ts[0]
+				if t.Main == shaderir.None {
+					t = toDefaultType(r[0].Const)
+				}
+				block.addNamedLocalVariable(name, t, e.Pos())
 			}
 
 			if len(r) > 1 {
@@ -582,8 +586,12 @@ func (cs *compileState) assign(block *block, fname string, pos token.Pos, lhs, r
 				})
 			} else {
 				// For variable swapping, use temporary variables.
+				t := origts[0]
+				if t.Main == shaderir.None {
+					t = toDefaultType(r[0].Const)
+				}
 				block.vars = append(block.vars, variable{
-					typ: origts[0],
+					typ: t,
 				})
 				idx := len(block.vars) - 1
 				stmts = append(stmts,
@@ -632,7 +640,13 @@ func (cs *compileState) assign(block *block, fname string, pos token.Pos, lhs, r
 						}
 					}
 				}
-				block.addNamedLocalVariable(name, rhsTypes[i], e.Pos())
+				t := rhsTypes[i]
+				if t.Main == shaderir.None {
+					// TODO: This is to determine a type when the rhs is a constant,
+					// but there are no actual cases when len(lhs) != len(rhs). Is this correct?
+					t = toDefaultType(rhsExprs[i].Const)
+				}
+				block.addNamedLocalVariable(name, t, e.Pos())
 			}
 
 			l, _, ss, ok := cs.parseExpr(block, lhs[i], false)
@@ -660,3 +674,16 @@ func (cs *compileState) assign(block *block, fname string, pos token.Pos, lhs, r
 
 	return stmts, true
 }
+
+func toDefaultType(v gconstant.Value) shaderir.Type {
+	switch v.Kind() {
+	case gconstant.Bool:
+		return shaderir.Type{Main: shaderir.Bool}
+	case gconstant.Int:
+		return shaderir.Type{Main: shaderir.Int}
+	case gconstant.Float:
+		return shaderir.Type{Main: shaderir.Float}
+	}
+	// TODO: Should this be an error?
+	return shaderir.Type{}
+}

internal/shader/testdata/const3.expected.vs

@@ -0,0 +1,22 @@
+void F0(void);
+
+void F0(void) {
+	int l0 = 0;
+	int l1 = 0;
+	float l2 = float(0);
+	int l3 = 0;
+	int l4 = 0;
+	int l5 = 0;
+	float l6 = float(0);
+	float l7 = float(0);
+	bool l8 = false;
+	l0 = 1;
+	l1 = 1;
+	l2 = 1.0;
+	l3 = 1;
+	l5 = 1;
+	l4 = l5;
+	l7 = 1.0;
+	l6 = l7;
+	l8 = false;
+}

internal/shader/testdata/const3.go

@@ -0,0 +1,23 @@
+package main
+
+const a = 1
+const b float = 1
+const c int = 1
+const d, e = 1, 1.0
+const f = false
+
+func Foo() {
+	l0 := 1
+	la := a
+	lb := b
+	lc := c
+	ld, le := d, e
+	lf := f
+	_ = l0
+	_ = la
+	_ = lb
+	_ = lc
+	_ = ld
+	_ = le
+	_ = lf
+}