literals.go

     1  // Code generated by "go test -run=Generate -write=all"; DO NOT EDIT.
     2  // Source: ../../cmd/compile/internal/types2/literals.go
     3  
     4  // Copyright 2024 The Go Authors. All rights reserved.
     5  // Use of this source code is governed by a BSD-style
     6  // license that can be found in the LICENSE file.
     7  
     8  // This file implements typechecking of literals.
     9  
    10  package types
    11  
    12  import (
    13  	"go/ast"
    14  	"go/token"
    15  	. "internal/types/errors"
    16  	"strings"
    17  )
    18  
    19  // langCompat reports an error if the representation of a numeric
    20  // literal is not compatible with the current language version.
    21  func (check *Checker) langCompat(lit *ast.BasicLit) {
    22  	s := lit.Value
    23  	if len(s) <= 2 || check.allowVersion(go1_13) {
    24  		return
    25  	}
    26  	// len(s) > 2
    27  	if strings.Contains(s, "_") {
    28  		check.versionErrorf(lit, go1_13, "underscore in numeric literal")
    29  		return
    30  	}
    31  	if s[0] != '0' {
    32  		return
    33  	}
    34  	radix := s[1]
    35  	if radix == 'b' || radix == 'B' {
    36  		check.versionErrorf(lit, go1_13, "binary literal")
    37  		return
    38  	}
    39  	if radix == 'o' || radix == 'O' {
    40  		check.versionErrorf(lit, go1_13, "0o/0O-style octal literal")
    41  		return
    42  	}
    43  	if lit.Kind != token.INT && (radix == 'x' || radix == 'X') {
    44  		check.versionErrorf(lit, go1_13, "hexadecimal floating-point literal")
    45  	}
    46  }
    47  
    48  func (check *Checker) basicLit(x *operand, e *ast.BasicLit) {
    49  	switch e.Kind {
    50  	case token.INT, token.FLOAT, token.IMAG:
    51  		check.langCompat(e)
    52  		// The max. mantissa precision for untyped numeric values
    53  		// is 512 bits, or 4048 bits for each of the two integer
    54  		// parts of a fraction for floating-point numbers that are
    55  		// represented accurately in the go/constant package.
    56  		// Constant literals that are longer than this many bits
    57  		// are not meaningful; and excessively long constants may
    58  		// consume a lot of space and time for a useless conversion.
    59  		// Cap constant length with a generous upper limit that also
    60  		// allows for separators between all digits.
    61  		const limit = 10000
    62  		if len(e.Value) > limit {
    63  			check.errorf(e, InvalidConstVal, "excessively long constant: %s... (%d chars)", e.Value[:10], len(e.Value))
    64  			x.invalidate()
    65  			return
    66  		}
    67  	}
    68  	x.setConst(e.Kind, e.Value)
    69  	if !x.isValid() {
    70  		// The parser already establishes syntactic correctness.
    71  		// If we reach here it's because of number under-/overflow.
    72  		// TODO(gri) setConst (and in turn the go/constant package)
    73  		// should return an error describing the issue.
    74  		check.errorf(e, InvalidConstVal, "malformed constant: %s", e.Value)
    75  		x.invalidate()
    76  		return
    77  	}
    78  	// Ensure that integer values don't overflow (go.dev/issue/54280).
    79  	x.expr = e // make sure that check.overflow below has an error position
    80  	check.overflow(x, opPos(x.expr))
    81  }
    82  
    83  func (check *Checker) funcLit(x *operand, e *ast.FuncLit) {
    84  	if sig, ok := check.typ(e.Type).(*Signature); ok {
    85  		// Set the Scope's extent to the complete "func (...) {...}"
    86  		// so that Scope.Innermost works correctly.
    87  		sig.scope.pos = e.Pos()
    88  		sig.scope.end = endPos(e)
    89  		if !check.conf.IgnoreFuncBodies && e.Body != nil {
    90  			// Anonymous functions are considered part of the
    91  			// init expression/func declaration which contains
    92  			// them: use existing package-level declaration info.
    93  			decl := check.decl // capture for use in closure below
    94  			iota := check.iota // capture for use in closure below (go.dev/issue/22345)
    95  			// Don't type-check right away because the function may
    96  			// be part of a type definition to which the function
    97  			// body refers. Instead, type-check as soon as possible,
    98  			// but before the enclosing scope contents changes (go.dev/issue/22992).
    99  			check.later(func() {
   100  				check.funcBody(decl, "<function literal>", sig, e.Body, iota)
   101  			}).describef(e, "func literal")
   102  		}
   103  		x.mode_ = value
   104  		x.typ_ = sig
   105  	} else {
   106  		check.errorf(e, InvalidSyntaxTree, "invalid function literal %v", e)
   107  		x.invalidate()
   108  	}
   109  }
   110  
   111  func (check *Checker) compositeLit(U Type, x *operand, e *ast.CompositeLit, hint Type) {
   112  	var typ, base Type
   113  	var isElem bool // true if composite literal is an element of an enclosing composite literal
   114  
   115  	switch {
   116  	case e.Type != nil:
   117  		// composite literal type present - use it
   118  		// [...]T array types may only appear with composite literals.
   119  		// Check for them here so we don't have to handle ... in general.
   120  		if atyp, _ := e.Type.(*ast.ArrayType); atyp != nil && isdddArray(atyp) {
   121  			// We have an "open" [...]T array type.
   122  			// Create a new ArrayType with unknown length (-1)
   123  			// and finish setting it up after analyzing the literal.
   124  			typ = &Array{len: -1, elem: check.varType(atyp.Elt)}
   125  			base = typ
   126  			break
   127  		}
   128  		typ = check.typ(e.Type)
   129  		base = typ
   130  
   131  	// The hint mechanism is kept around to avoid reporting a false "need Go 1.28" error
   132  	// for users of a Go 1.27 compiler.
   133  	case hint != nil:
   134  		// no composite literal type present - use hint (element type of enclosing type)
   135  		typ = hint
   136  		base = typ
   137  		// *T implies &T{}
   138  		u, _ := commonUnder(base, nil)
   139  		if b, ok := deref(u); ok {
   140  			base = b
   141  		}
   142  		isElem = true
   143  
   144  	default:
   145  		// no composite literal type or hint present - use assignment context (if available and past Go 1.28)
   146  		if U != nil {
   147  			// report a version error only if we have an inferred type
   148  			check.verifyVersionf(e, go1_28, "missing type in composite literal")
   149  			// continue with the inferred type regardless of version
   150  			typ = U
   151  			base = typ
   152  			// *T implies &T{}
   153  			u, _ := commonUnder(base, nil)
   154  			if b, ok := deref(u); ok {
   155  				base = b
   156  			}
   157  		} else {
   158  			// TODO(gri) provide better error messages depending on context
   159  			check.error(e, UntypedLit, "missing type in composite literal")
   160  			// continue with invalid type so that elements are "used" (go.dev/issue/69092)
   161  			typ = Typ[Invalid]
   162  			base = typ
   163  		}
   164  	}
   165  
   166  	// We cannot create a literal of an incomplete type; make sure it's complete.
   167  	if !check.isComplete(base) {
   168  		x.invalidate()
   169  		return
   170  	}
   171  
   172  	switch u, _ := commonUnder(base, nil); utyp := u.(type) {
   173  	case *Struct:
   174  		if len(e.Elts) == 0 {
   175  			break
   176  		}
   177  		// Convention for error messages on invalid struct literals:
   178  		// we mention the struct type only if it clarifies the error
   179  		// (e.g., a duplicate field error doesn't need the struct type).
   180  		fields := utyp.fields
   181  		if _, ok := e.Elts[0].(*ast.KeyValueExpr); ok {
   182  			// all elements must have keys
   183  			visited := make(trie[*Var])
   184  			for _, e := range e.Elts {
   185  				kv, _ := e.(*ast.KeyValueExpr)
   186  				if kv == nil {
   187  					check.error(e, MixedStructLit, "mixture of field:value and value elements in struct literal")
   188  					continue
   189  				}
   190  				key, _ := kv.Key.(*ast.Ident)
   191  				// do all possible checks early (before exiting due to errors)
   192  				// so we don't drop information on the floor
   193  				if key == nil {
   194  					check.genericExpr(nil, x, kv.Value, nil)
   195  					check.errorf(kv, InvalidLitField, "invalid field name %s in struct literal", kv.Key)
   196  					continue
   197  				}
   198  				obj, index, indirect := lookupFieldOrMethod(utyp, false, check.pkg, key.Name, false)
   199  				if obj == nil {
   200  					check.genericExpr(nil, x, kv.Value, nil)
   201  					alt, _, _ := lookupFieldOrMethod(utyp, false, check.pkg, key.Name, true)
   202  					msg := check.lookupError(base, key.Name, alt, true)
   203  					check.error(kv.Key, MissingLitField, msg)
   204  					continue
   205  				}
   206  				fld, _ := obj.(*Var)
   207  				if fld == nil {
   208  					check.genericExpr(nil, x, kv.Value, nil)
   209  					check.errorf(kv.Key, MissingLitField, "%s is not a field", kv.Key)
   210  					continue
   211  				}
   212  				// we can now check the value using the field target type
   213  				etyp := fld.typ
   214  				check.genericExpr(etyp, x, kv.Value, nil)
   215  				if len(index) > 1 && !check.verifyVersionf(kv.Key, go1_27, "use of promoted field %s in struct literal of type %s", fieldPath(utyp, index), base) {
   216  					continue
   217  				}
   218  				if indirect {
   219  					check.errorf(kv.Key, InvalidLitField, "invalid implicit pointer indirection to reach %s", kv.Key)
   220  					continue
   221  				}
   222  				check.recordUse(key, fld)
   223  				check.assignment(x, etyp, "struct literal")
   224  				if alt, n := visited.insert(index, fld); n != 0 {
   225  					if fld == alt {
   226  						check.errorf(kv, DuplicateLitField, "duplicate field name %s in struct literal", fld.name)
   227  					} else if n < len(index) {
   228  						check.errorf(kv, DuplicateLitField, "cannot specify promoted field %s and enclosing embedded field %s", fld.name, alt.name)
   229  					} else { // n > len(index)
   230  						check.errorf(kv, DuplicateLitField, "cannot specify embedded field %s and enclosed promoted field %s", fld.name, alt.name)
   231  					}
   232  				}
   233  			}
   234  		} else {
   235  			// no element must have a key
   236  			for i, e := range e.Elts {
   237  				if kv, _ := e.(*ast.KeyValueExpr); kv != nil {
   238  					check.error(kv, MixedStructLit, "mixture of field:value and value elements in struct literal")
   239  					continue
   240  				}
   241  				if i >= len(fields) {
   242  					check.genericExpr(nil, x, e, nil)
   243  					check.errorf(x, InvalidStructLit, "too many values in struct literal of type %s", base)
   244  					break // cannot continue
   245  				}
   246  				// i < len(fields)
   247  				fld := fields[i]
   248  				etyp := fld.typ
   249  				check.genericExpr(etyp, x, e, nil)
   250  				if !fld.Exported() && fld.pkg != check.pkg {
   251  					check.errorf(x, UnexportedLitField, "implicit assignment to unexported field %s in struct literal of type %s", fld.name, base)
   252  					continue
   253  				}
   254  				check.assignment(x, etyp, "struct literal")
   255  			}
   256  			if len(e.Elts) < len(fields) {
   257  				var hint string
   258  				for _, fld := range fields {
   259  					if !fld.Exported() && fld.pkg != check.pkg {
   260  						hint = " (type has unexported fields - use key:value pairs)"
   261  						break
   262  					}
   263  				}
   264  				check.errorf(inNode(e, e.Rbrace), InvalidStructLit, "too few values in struct literal of type %s%s", base, hint)
   265  				// ok to continue
   266  			}
   267  		}
   268  
   269  	case *Array:
   270  		n := check.indexedElts(e.Elts, utyp.elem, utyp.len)
   271  		// If we have an array of unknown length (usually [...]T arrays, but also
   272  		// arrays [n]T where n is invalid) set the length now that we know it and
   273  		// record the type for the array (usually done by check.typ which is not
   274  		// called for [...]T). We handle [...]T arrays and arrays with invalid
   275  		// length the same here because it makes sense to "guess" the length for
   276  		// the latter if we have a composite literal; e.g. for [n]int{1, 2, 3}
   277  		// where n is invalid for some reason, it seems fair to assume it should
   278  		// be 3 (see also Checked.arrayLength and go.dev/issue/27346).
   279  		if utyp.len < 0 {
   280  			utyp.len = n
   281  			// e.Type is missing if we have a composite literal element
   282  			// that is itself a composite literal with omitted type. In
   283  			// that case there is nothing to record (there is no type in
   284  			// the source at that point).
   285  			if e.Type != nil {
   286  				check.recordTypeAndValue(e.Type, typexpr, utyp, nil)
   287  			}
   288  		}
   289  
   290  	case *Slice:
   291  		check.indexedElts(e.Elts, utyp.elem, -1)
   292  
   293  	case *Map:
   294  		// If the map key type is an interface (but not a type parameter),
   295  		// the type of a constant key must be considered when checking for
   296  		// duplicates.
   297  		keyIsInterface := isNonTypeParamInterface(utyp.key)
   298  		visited := make(map[any][]Type, len(e.Elts))
   299  		for _, e := range e.Elts {
   300  			kv, _ := e.(*ast.KeyValueExpr)
   301  			if kv == nil {
   302  				check.error(e, MissingLitKey, "missing key in map literal")
   303  				continue
   304  			}
   305  			check.genericExpr(utyp.key, x, kv.Key, utyp.key)
   306  			check.assignment(x, utyp.key, "map literal")
   307  			if !x.isValid() {
   308  				continue
   309  			}
   310  			if x.mode() == constant_ {
   311  				duplicate := false
   312  				xkey := keyVal(x.val)
   313  				if keyIsInterface {
   314  					for _, vtyp := range visited[xkey] {
   315  						if Identical(vtyp, x.typ()) {
   316  							duplicate = true
   317  							break
   318  						}
   319  					}
   320  					visited[xkey] = append(visited[xkey], x.typ())
   321  				} else {
   322  					_, duplicate = visited[xkey]
   323  					visited[xkey] = nil
   324  				}
   325  				if duplicate {
   326  					check.errorf(x, DuplicateLitKey, "duplicate key %s in map literal", x.val)
   327  					continue
   328  				}
   329  			}
   330  			check.genericExpr(utyp.elem, x, kv.Value, utyp.elem)
   331  			check.assignment(x, utyp.elem, "map literal")
   332  		}
   333  
   334  	default:
   335  		// when "using" all elements unpack KeyValueExpr
   336  		// explicitly because check.use doesn't accept them
   337  		for _, e := range e.Elts {
   338  			if kv, _ := e.(*ast.KeyValueExpr); kv != nil {
   339  				// Ideally, we should also "use" kv.Key but we can't know
   340  				// if it's an externally defined struct key or not. Going
   341  				// forward anyway can lead to other errors. Give up instead.
   342  				e = kv.Value
   343  			}
   344  			check.use(e)
   345  		}
   346  		// if utyp is invalid, an error was reported before
   347  		if isValid(utyp) {
   348  			var qualifier string
   349  			if isElem {
   350  				qualifier = " element"
   351  			}
   352  			var cause string
   353  			if utyp == nil {
   354  				cause = " (no common underlying type)"
   355  			}
   356  			check.errorf(e, InvalidLit, "invalid composite literal%s type %s%s", qualifier, typ, cause)
   357  			x.invalidate()
   358  			return
   359  		}
   360  	}
   361  
   362  	x.mode_ = value
   363  	x.typ_ = typ
   364  }
   365  
   366  // indexedElts checks the elements (elts) of an array or slice composite literal
   367  // against the literal's element type (typ), and the element indices against
   368  // the literal length if known (length >= 0). It returns the length of the
   369  // literal (maximum index value + 1).
   370  func (check *Checker) indexedElts(elts []ast.Expr, typ Type, length int64) int64 {
   371  	visited := make(map[int64]bool, len(elts))
   372  	var index, max int64
   373  	for _, e := range elts {
   374  		// determine and check index
   375  		validIndex := false
   376  		eval := e
   377  		if kv, _ := e.(*ast.KeyValueExpr); kv != nil {
   378  			if typ, i := check.index(kv.Key, length); isValid(typ) {
   379  				if i >= 0 {
   380  					index = i
   381  					validIndex = true
   382  				} else {
   383  					check.errorf(e, InvalidLitIndex, "index %s must be integer constant", kv.Key)
   384  				}
   385  			}
   386  			eval = kv.Value
   387  		} else if length >= 0 && index >= length {
   388  			check.errorf(e, OversizeArrayLit, "index %d is out of bounds (>= %d)", index, length)
   389  		} else {
   390  			validIndex = true
   391  		}
   392  
   393  		// if we have a valid index, check for duplicate entries
   394  		if validIndex {
   395  			if visited[index] {
   396  				check.errorf(e, DuplicateLitKey, "duplicate index %d in array or slice literal", index)
   397  			}
   398  			visited[index] = true
   399  		}
   400  		index++
   401  		if index > max {
   402  			max = index
   403  		}
   404  
   405  		// check element against composite literal element type
   406  		var x operand
   407  		check.genericExpr(typ, &x, eval, typ)
   408  		check.assignment(&x, typ, "array or slice literal")
   409  	}
   410  	return max
   411  }
   412
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