Teyru diagnostics at a glance
The stable code format TY-<stage>-<four digits> of every diagnostic, and the representative messages for each stage.
Every diagnostic has a stable code, with the format TY-<stage>-<four digits>. Stage prefixes:
| Prefix | Stage | Representative |
|---|---|---|
TY-SYN | Lexing and parsing | Semicolons, parentheses, line breaks, literals |
TY-TYP | Semantic analysis (names, types, members) | Symbol not found, type mismatch, overloading |
TY-PROP | Native property rules | Accessor conflicts, storage requirements |
TY-INT | Compiler internals / prelude library | Corrupt prelude, unsupported nodes |
TY-IO | File access | Source file cannot be read |
The output format is file:line:column: error[code]: message, for example:
hello.teyru:4:11: error[TY-TYP-0051]: incompatible types: String cannot be converted to intTY-SYN-0001, 0002, 0004–0011 are produced by the lexer (TY-SYN-0003 is the exception: it is
emitted by the parser at the end of a statement and at a throw line break), and everything from
TY-SYN-0100 onwards is produced by the parser too.
TY-SYN: lexing and parsing
| Code | Message | Explanation and fix |
|---|---|---|
| TY-SYN-0001 | ';' is not Teyru syntax; end statements with a newline | Teyru has no semicolons. Delete the semicolon and let the statement end with a newline; in a for header, separate the parts with a colon instead. |
| TY-SYN-0002 | unexpected character %q | A character that belongs to no token appeared (usually a full-width punctuation mark or a pasted control character). |
| TY-SYN-0003 | expected end of line, found %s／throw expression must start on the same line | There are leftover tokens after the statement; or the throw expression is cut off by a line break. Write the expression on the same line, or start it with ( so that it spans lines. A yield that needs a value does not get this message: after a line break it is treated as an identifier, and you get cannot find symbol yield. |
| TY-SYN-0004 | unterminated block comment | A /* with no matching */. |
| TY-SYN-0005 | invalid unicode escape | \uXXXX is not four hexadecimal digits. |
| TY-SYN-0006 | unterminated string literal／unterminated text block | The string is not closed before the line break, or the text block is missing its closing """. |
| TY-SYN-0007 | text block must start with a line break after """ | A line break must follow """ immediately. |
| TY-SYN-0008 | unterminated character literal／character literal does not fit in a char | The character literal is not terminated, or it exceeds U+FFFF. |
| TY-SYN-0009 | malformed integer literal／malformed floating-point literal | Malformed number (for example no digits after 0x, or 1e with no exponent). |
| TY-SYN-0010 | integer literal out of range | The integer literal exceeds the number of bits that can be represented: decimal int is limited to 2^31-1 and long to 2^63-1, non-decimal int to 0xFFFFFFFF and long to 0xFFFFFFFFFFFFFFFF (boundary values wrap round to negative). For a larger value, add the L suffix. |
| TY-SYN-0011 | invalid escape sequence \%c | The string or character literal contains an escape sequence Teyru does not recognise (for example \q). The valid ones are \n \t \r \b \f \s \0 \\ \' \", octal \nnn and \uXXXX. |
| TY-SYN-0100 | expected '%s', found %s | A token that was expected is missing (), ], {, }, : and so on). |
| TY-SYN-0101 | expected identifier, found %s | Something else sits where an identifier is required; common when a keyword is used as a name. |
| TY-SYN-0102 | unexpected %s at top level | The top level of a file allows only package/import/type declarations, or members written directly (the implicit class form). |
| TY-SYN-0103 | unexpected %s in class body | The class member declaration is incomplete. |
| TY-SYN-0104 | expected ',' ':' or '}' after enum constants | The enum constant section and the member section must be separated by a single :. |
| TY-SYN-0105 | expected 'get' or 'set' accessor, found %s | Only get and set may appear in an accessor block. |
| TY-SYN-0106 | unexpected %s | A statement that cannot be parsed appears in the block. |
| TY-SYN-0107 | try resources must be separated by line breaks | Separate each try-with-resources resource with a line break, not a semicolon. |
| TY-SYN-0108 | try requires catch or finally | A try needs at least one catch or finally. |
| TY-SYN-0109 | expected 'case' or 'default', found %s | Only case/default may appear in a switch block. |
| TY-SYN-0110 | cannot mix '->' and ':' case labels | A single switch may use only one form of label. |
| TY-SYN-0111 | expected expression, found %s | Another token sits where an expression is required. |
| TY-SYN-0112 | array dimension expression after empty dimension | [5] cannot be written after new int[3][]. |
| TY-SYN-0113 | array creation with both dimensions and initializer | new int[3]{1,2,3} is not legal; give either a size or initial values. |
TY-TYP: types and symbols
Declarations and members (0001–0025)
| Code | Message | Explanation and fix |
|---|---|---|
| TY-TYP-0001 | duplicate type %s (also declared at %s)／duplicate nested type %s | A type with the same name is declared twice. |
| TY-TYP-0002 | type variable %s cannot have type arguments | A type variable cannot itself carry type arguments. |
| TY-TYP-0003 | cannot find type %s | The type name cannot be found; check the spelling, the import or the prelude. |
| TY-TYP-0004 | type %s expects %d type arguments, found %d | The number of generic arguments does not match. |
| TY-TYP-0005 | primitive type %s cannot be a type argument; use its box type | Generics cannot use a primitive type; use the wrapper class. |
| TY-TYP-0006 | class cannot extend interface %s | A class uses implements for an interface. |
| TY-TYP-0007 | cannot extend final class %s | A class marked final cannot be extended. When final is applied by @Value/@UtilityClass, this is reported only after annotation expansion (the “block inheritance” check used to run before expansion, so those two annotations had no effect). |
| TY-TYP-0008 | cyclic inheritance involving %s | The inheritance relationship forms a cycle. |
| TY-TYP-0009 | %s is not an interface | Only an interface may follow implements. |
| TY-TYP-0010 | duplicate field %s in %s | A field is declared twice in the same class. |
| TY-TYP-0011 | duplicate method %s in %s／duplicate constructor %s | A method or constructor with the same signature after parameter erasure is declared twice. |
| TY-TYP-0012 | varargs parameter must be last | ... may only go on the last parameter. |
| TY-TYP-0013 | interface method with a body must be default, static or private | An interface method with a body must be marked default/static/private. |
| TY-TYP-0014 | method %s needs a body | A non-abstract method needs a body. |
| TY-TYP-0015 | abstract or native method %s cannot have a body | An abstract/native method cannot have a body. |
| TY-TYP-0016 | abstract method %s in non-abstract class %s | A class with abstract methods must be marked abstract. |
| TY-TYP-0017 | (removed) | A native method can now be declared in any class and implemented in C supplied through --native. |
| TY-TYP-0018 | '%s' is only allowed for local variables; fields need an explicit type | var/val cannot be used for a field, a parameter or a return type. |
| TY-TYP-0019 | %s must implement %s from %s | A concrete class does not implement an abstract method of an interface or superclass. |
| TY-TYP-0020 | missing return statement | A method with a return value has paths that lack a return. |
| TY-TYP-0021 | duplicate local variable %s | A local variable is declared twice in the same scope. |
| TY-TYP-0022 | break outside of loop or switch | break may only appear inside a loop or switch (the labelled form is the exception). |
| TY-TYP-0023 | continue outside of loop | continue may only appear inside a loop. |
| TY-TYP-0024 | thrown value must be a Throwable, found %s | The object thrown by throw must extend Throwable. |
| TY-TYP-0025 | cannot synchronize on void | The lock of a synchronized cannot be a void expression. |
Statements (0026–0044)
| Code | Message | Explanation and fix |
|---|---|---|
| TY-TYP-0026 | local variables cannot be declared final; use 'val' | Use val for a local variable that cannot be rebound. |
| TY-TYP-0027 | '%s' requires an initializer | var/val must have an initial value. |
| TY-TYP-0028 | '%s' cannot infer a type from null | A type cannot be inferred from null; write the type out explicitly. |
| TY-TYP-0029 | '%s' cannot infer a functional interface type; declare it explicitly | A lambda needs a target type; declare the interface type explicitly. |
| TY-TYP-0030 | for-each requires an array or Iterable, found %s | The enhanced for only works on an array or an Iterable. |
| TY-TYP-0031 | incompatible types: %s is not assignable to %s | The loop variable type does not match the element type. |
| TY-TYP-0032 | return value required for %s | A method with a return value cannot return empty-handed. |
| TY-TYP-0033 | cannot return a value from a void method | A void method cannot return a value. |
| TY-TYP-0034 | catch type must be a Throwable, found %s | The catch type must be from the Throwable family. |
| TY-TYP-0035 | switch selector must be a char, byte, short, int, Character, Byte, Short, Integer, String or enum type, found %s | The selector type of the switch is not legal. |
| TY-TYP-0036 | duplicate default label | A single switch may have only one default. |
| TY-TYP-0037 | incompatible pattern type %s for switch on %s | case <type> <name> is unrelated to the selector type. |
| TY-TYP-0038 | case label must be a constant expression | A case label must be a compile-time constant. |
| TY-TYP-0039 | duplicate case label | A label is duplicated within the same switch. |
| TY-TYP-0040 | array required, found %s | [] is used on something that is not an array. |
| TY-TYP-0041 | inconvertible types: %s cannot be cast to %s | This cast can never succeed. |
| TY-TYP-0042 | incompatible pattern type %s for %s | The type of the instanceof pattern is unrelated to the left-hand side. |
| TY-TYP-0043 | not an enclosing class: %s | The enclosing class of Outer.this does not exist. |
| TY-TYP-0044 | no superclass | super is used although there is no superclass. |
Names and access (0045–0048)
| Code | Message | Explanation and fix |
|---|---|---|
| TY-TYP-0045 | cannot access instance field %s from a static context | An instance field cannot be read directly inside a static method. |
| TY-TYP-0046 | %s has private access in %s | A private member can only be accessed inside its own class. For a property, what counts is the modifier of the accessor (the underlying storage is always private, so the modifiers of the storage field cannot be used to decide); x.p = v looks at the setter, while p.x and p.x += 1 look at the getter. Access is mutual within the same nest (the same top-level class). |
| TY-TYP-0048 | cannot find symbol %s | The name cannot be found: check the spelling, the scope, the import, or whether you forgot to declare it. |
Conversions and operators (0049–0067)
| Code | Message | Explanation and fix |
|---|---|---|
| TY-TYP-0049 | null is not assignable to %s | null cannot be given to a primitive type. |
| TY-TYP-0050 | possible lossy conversion from %s to %s | A narrowing conversion is needed; add a cast. |
| TY-TYP-0051 | incompatible types: %s cannot be converted to %s | The most common type error: the types of an assignment, an argument or a return are incompatible. |
| TY-TYP-0052 | operator '!' cannot be applied to %s | ! only works on boolean. |
| TY-TYP-0053 | operator '~' requires an integral operand | ~ only works on integers. |
| TY-TYP-0054 | operator '%s' requires a numeric operand | Unary +/- only works on numeric values. |
| TY-TYP-0055 | operator '%s' requires a numeric operand | ++/-- only works on numeric values. |
| TY-TYP-0056 | cannot apply '%s' to a non-assignable expression | The target of ++/-- must be assignable. |
| TY-TYP-0057 | cannot assign a value to final variable %s | A val or final variable cannot be assigned again. |
| TY-TYP-0058 | cannot assign a value to final field %s | A final field of another class cannot be assigned. |
| TY-TYP-0059 | incompatible operand types %s and %s | The two sides of ==/!= cannot be compared. |
| TY-TYP-0060 | incomparable types: %s and %s | Two reference types can never be equal. |
| TY-TYP-0061 | operator '%s' cannot be applied to %s and %s | Ordering comparisons only work on numeric values. |
| TY-TYP-0062 | operator '%s' requires integral or boolean operands | The operand type of &/|/^ is not legal. |
| TY-TYP-0063 | operator '%s' requires integral operands | The shift operators only work on integers. |
| TY-TYP-0064 | operator '%s' cannot be applied to %s and %s | The operand of an arithmetic operator is not numeric (a common case: an object that was not unboxed). |
| TY-TYP-0065 | left-hand side of an assignment must be a variable | The left-hand side of an assignment cannot be an arbitrary expression. |
| TY-TYP-0066 | operator '%s' cannot be applied to boolean | boolean cannot be added, subtracted, multiplied or divided. |
| TY-TYP-0067 | array dimension must be non-negative | The array size is a negative constant. |
Construction and instantiation (0068–0075)
| Code | Message | Explanation and fix |
|---|---|---|
| TY-TYP-0068 | cannot instantiate %s | This type cannot be used with new. |
| TY-TYP-0069 | %s is abstract; cannot be instantiated | An abstract class cannot be newed directly. |
| TY-TYP-0070 | cannot extend final class %s／cannot subclass enum %s | An anonymous class cannot extend a final class or an enum. |
| TY-TYP-0071 | an enclosing instance of %s is required | An inner class has to be created where an enclosing instance exists. |
| TY-TYP-0072 | no suitable constructor found for %s(%s) | No matching constructor; check the number and the types of the arguments. |
| TY-TYP-0073 | array clone takes no arguments | clone() takes no arguments. |
| TY-TYP-0074 | this(...) and super(...) may only be called from a constructor | this(...)/super(...) may only be written inside a constructor (it can be one of the “statements before super()” that JEP 513 allows, see docs/language.md §4.2). |
| TY-TYP-0075 | recursive constructor invocation | The constructor calls itself recursively. |
Method resolution, lambda and pattern (0076–0094)
| Code | Message | Explanation and fix |
|---|---|---|
| TY-TYP-0076 | cannot find method %s(%s)／cannot find method %s for this functional interface | The method cannot be found: check the name, the parameter types, the visibility or the receiver type. |
| TY-TYP-0077 | non-static method %s cannot be referenced from a type name | Only static methods can be called through a class name. |
| TY-TYP-0078 | cannot invoke %s on %s | Calling a method on this type is not legal. |
| TY-TYP-0079 | %s has %s access in %s | The method is not visible enough. |
| TY-TYP-0080 | cannot find symbol %s in %s／on array | The member does not exist on that type. |
| TY-TYP-0081 | cannot infer the functional interface for this lambda; declare the target type／cannot infer the functional interface for this method reference | The lambda/method reference has no target type; specify one explicitly. |
| TY-TYP-0082 | lambda target type must be a functional interface, found %s／method reference target type must be a functional interface | The target type is not an interface. |
| TY-TYP-0083 | %s is not a functional interface | The interface has several abstract methods and cannot be a lambda target. |
| TY-TYP-0084 | lambda has %d parameters but %s requires %d | The number of lambda parameters does not match. |
| TY-TYP-0085 | cannot construct %s | The target of the constructor reference cannot be constructed. |
| TY-TYP-0086 | cannot resolve static import %s | No matching member can be found for the static import. |
| TY-TYP-0087 | record pattern requires a record type, found %s | The left-hand side of the destructuring pattern is not a record type (the Point in case Point(int x, int y) must be a record). |
| TY-TYP-0088 | record pattern for %s needs %d components, found %d | The number of bindings in the destructuring does not match the number of record components; a nested destructuring has to match up item by item as well. |
| TY-TYP-0089 | 'case null' requires a reference selector | case null only works on a switch selector of reference type; for a primitive type use default instead. |
| TY-TYP-0090 | %s does not name a super interface | The Interface in Interface.super.method() does not exist or is not an interface. |
| TY-TYP-0091 | %s is not a super interface of %s | A qualified super can only point at an interface the class itself implements (directly or indirectly). |
| TY-TYP-0092 | a primitive pattern needs a name to bind the value to | A primitive pattern must bind a variable: o instanceof int i, not just o instanceof int. |
| TY-TYP-0093 | boolean cannot be converted to %s | boolean can only be matched by a boolean pattern. |
| TY-TYP-0094 | primitive pattern %s needs a boxed value, found %s | The selector is neither a reference type nor a primitive numeric value. |
| TY-IO-0101 | An error in the module file itself (teyru.mod cannot be parsed, wrong version syntax…) | The message comes from internal/mod and names the file and the reason. |
| TY-IO-0102 | cannot read package %s: %v | The imported package is not found in the module cache, or its source files cannot be read. Run teyru mod tidy or teyru get first. |
| TY-IO-0103 | Hash mismatch for teyru.sum | The module contents in the cache differ from what teyru.sum records. Either the dependency was changed or the cache was touched; the build stops instead of using it. |
| TY-IO-0104 | %s declares package %s, but %s in the same directory declares %s | Two files in the same directory declare different packages. |
| TY-TYP-0095 | cannot infer the type arguments of %s(%s) | The type arguments of the generic method cannot be inferred: there is no argument that carries a type and no target type to use (lambda parameters are the most common case). Write the type arguments, or pass an argument that has a type. |
| TY-TYP-0096 | switch expression does not cover all possible input values | A switch expression must be exhaustive: an int/String selector must have a default, and an enum selector must cover every constant. A switch statement is not subject to this. |
| TY-TYP-0097 | native methods %s and %s both need the C symbol %s | Two overloaded native methods encode to the same C symbol (for example the class name AI and int[]). Rename one or change a parameter type. |
| TY-TYP-0098 | non-static %s cannot be referenced from a static context | The lambda body uses the this of the place where it is written (including unqualified instance method calls, bare field names and super), but the lambda is written in a static method or a static initialiser block, so there is no instance to capture. Java rejects it as well. |
| TY-TYP-0108 | (removed) | The JSON binding reads the class at run time; there is no step that generates one. |
| TY-TYP-0109 | (removed) | As above: two fields of one @SerializedName name are only visible when they are read. |
| TY-TYP-0112 | (removed) | A class read from JSON is built at run time, so a constructor that cannot be called shows up at newInstance. |
| TY-TYP-0111 | (removed) | A controller's answer is written as JSON by the binding whatever type it is. |
| TY-TYP-0110 | (removed) | Whether a field's type binds is something the reading finds out. |
| TY-TYP-0114 | not a statement: %s has no effect | An expression statement without a side effect (JLS 14.8). This language ends an expression at the line break, so long x = a followed by a newline and + b are two statements, the second a silent unary plus — x comes up one term short with no message at all. It is reported now. |
| TY-TYP-0113 | resource type %s is not a subtype of AutoCloseable | The resource type of try-with-resources must be a subtype of AutoCloseable. The implicit close() is one interface call, so a class that merely “happens to have a close() method” compiles into an itable call on an object that has no such entry, and blows up at run time. |
| TY-TYP-0115 | cannot resolve import %s | The import path points at nothing. In Teyru a name is looked up by its simple name, and whatever package is written in front makes no difference, so a misspelt package such as import java.utli.List used to be ignored silently and you still got List. Now an import has to point at: a package the standard library answers for (the teyru package itself, plus java.util, com.google.gson, lombok… for compatibility, see docs/language.md §11), a package declared by some file in this build, or a type whose fully qualified name is exactly this path. |
| TY-TYP-0100 | (removed) | Two beans of one name are refused by the container at refresh(). |
| TY-TYP-0101 | %s is declared by the framework and cannot be redefined | __TeyruFramework is the generated class the container's registry lives in; its name is reserved. |
| TY-TYP-0102 | @Bean method %s must not be static / @Bean method %s must return the bean's type / @Bean method %s does not return a class type | A @Bean method must not be static and must return a class type (a primitive is boxed). |
| TY-TYP-0103 | (removed) | A missing bean is an exception at refresh() now, which is when Spring finds out too. |
| TY-TYP-0104 | (removed) | Two candidates are an exception at refresh(), with both names in the message. |
| TY-TYP-0105 | (removed) | Which constructor to call is decided at run time: the @Autowired one, the only one, or the one that takes nothing. |
| TY-TYP-0106 | (removed) | A @PostConstruct signature is checked when it is called. |
| TY-TYP-0107 | (removed) | A dependency loop is an exception at refresh(), with the cycle in the message. |
| TY-TYP-0099 | reference to %s is ambiguous: it is declared in both %s and %s | Two import p.* both provide the same simple name (JLS 6.5.5.1). Write the fully qualified name or disambiguate with a single-type import (import a.Widget). |
TY-PROP: native property
| Code | Message | Explanation and fix |
|---|---|---|
| TY-PROP-0001 | a property declaration must declare exactly one name | A property can declare only one name. |
| TY-PROP-0002 | duplicate get accessor／duplicate set accessor | get/set may each appear only once. |
| TY-PROP-0003 | computed property %s cannot use storage modifiers | A property without storage cannot use final/volatile/transient. |
| TY-PROP-0004 | final property %s cannot declare a setter | A final property cannot have a setter. |
| TY-PROP-0005 | property %s has no getter | A property with only a setter cannot be read; inside the accessor, use field. |
| TY-PROP-0007 | property %s has no setter | A property with only a getter cannot be assigned. |
| TY-PROP-0008 | property %s needs a getter for compound assignment | p.x += 1 needs a getter and a setter. |
TY-INT and TY-IO
| Code | Message | Explanation |
|---|---|---|
| TY-INT-0001 | prelude is missing class %s | The prelude is corrupt or the class was overridden; this is an internal compiler error. |
| TY-INT-0002 | unsupported expression %T | Semantic analysis met a node it does not handle; this is an internal compiler error (please report it). |
| TY-INT-0004 | @Singular goes on a builder field, not on the class | On a class it means nothing. |
| TY-INT-0005 | @Singular needs a List or Map field, found %s | @Singular only works on a collection field. |
| TY-INT-0006 | @CustomLog needs %s in a %s file in the source file's directory or above it／@CustomLog cannot pass TYPE: …／@CustomLog: cannot resolve the factory class %q named by %s | @CustomLog relies on lombok.log.custom.declaration in lombok.config to know how to build the logger (see docs/lombok.md for how it is read): a missing key, a pattern that uses TYPE, or a pattern naming a class that cannot be found are all reported here. You can also switch to @Log or declare the field yourself. |
| TY-IO-0001 | cannot read %s: %v | The source file cannot be read; check the path and the permissions. |
Runtime errors
A run-time failure is not a diagnostic code but a member of the Throwable family:
| Exception | When it is thrown |
|---|---|
NullPointerException | Unboxing null, or reading/writing a field, calling a method (String methods, clone(), interface methods and virtual calls all count), reading/writing an array element or taking length |
ArrayIndexOutOfBoundsException | An array index outside [0, length) (both reads and writes; a null array throws NullPointerException first) |
IndexOutOfBoundsException | The index of ArrayList.get/set/remove outside [0, size) |
NoSuchElementException | Iterator.next() called again although there are no elements left |
ArithmeticException | Integer division by zero or remainder by zero |
ClassCastException | A cast that fails, through cast or instanceof |
NegativeArraySizeException | A negative array length |
AssertionError | A failed assert |
IllegalArgumentException | enum.valueOf cannot find the constant, and so on |
An exception that is not caught prints Exception in thread "main" … and exits with status 1.
Reaching an abstract method that has no implementation prints teyru: no implementation for … and exits with status 70.
Teyru Language Reference
The syntax and semantics of Teyru 0.2: source files and lexing, types, declarations, native properties, statements, generics, lambdas, exceptions and the standard library.
Lombok compatibility layer
The compiler's built-in Lombok compatibility layer: annotations are expanded into ordinary Teyru members during semantic analysis, with no annotation processor required.