internal/shader: implement strict type checks when calling a function

Closes #2032

internal/shader/expr.go

@@ -444,6 +444,11 @@ func (cs *compileState) parseExpr(block *block, expr ast.Expr, markLocalVariable
 					return nil, nil, nil, false
 				}
 			}
+
+			if !canAssign(&args[i], &p, &argts[i]) {
+				cs.addError(e.Pos(), fmt.Sprintf("cannot use type %s as type %s in argument", argts[i].String(), p.String()))
+				return nil, nil, nil, false
+			}
 		}
 
 		var outParams []int

internal/shader/syntax_test.go

@@ -1307,3 +1307,47 @@ func Fragment(position vec4, texCoord vec2, color vec4) vec4 {
 		t.Errorf("error must be non-nil but was nil")
 	}
 }
+
+// Issue #2032
+func TestSyntaxTypeFuncCall(t *testing.T) {
+	if _, err := compileToIR([]byte(`package main
+
+func Foo(x vec2) {
+}
+
+func Fragment(position vec4, texCoord vec2, color vec4) vec4 {
+	Foo(0)
+	return color
+}
+`)); err == nil {
+		t.Errorf("error must be non-nil but was nil")
+	}
+	if _, err := compileToIR([]byte(`package main
+
+func Foo(x vec2, y vec3) {
+}
+
+func Fragment(position vec4, texCoord vec2, color vec4) vec4 {
+	Foo(0, 1)
+	return color
+}
+`)); err == nil {
+		t.Errorf("error must be non-nil but was nil")
+	}
+	if _, err := compileToIR([]byte(`package main
+
+func Foo(x vec2, y vec3) {
+}
+
+func Bar() (int, int) {
+	return 0, 1
+}
+
+func Fragment(position vec4, texCoord vec2, color vec4) vec4 {
+	Foo(Bar())
+	return color
+}
+`)); err == nil {
+		t.Errorf("error must be non-nil but was nil")
+	}
+}