diff options
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/go_spec.html | 87 | ||||
| -rw-r--r-- | doc/godebug.md | 4 |
2 files changed, 53 insertions, 38 deletions
diff --git a/doc/go_spec.html b/doc/go_spec.html index f47f5a6e3e..478aefd4a6 100644 --- a/doc/go_spec.html +++ b/doc/go_spec.html @@ -1,6 +1,6 @@ <!--{ "Title": "The Go Programming Language Specification", - "Subtitle": "Language version go1.26 (Dec 2, 2025)", + "Subtitle": "Language version go1.26 (Jan 12, 2026)", "Path": "/ref/spec" }--> @@ -3143,7 +3143,8 @@ math.Sin // denotes the Sin function in package math <p> Composite literals construct new values for structs, arrays, slices, and maps each time they are evaluated. -They consist of the type of the literal followed by a brace-bound list of elements. +They consist of the type of the literal followed by a (possibly empty) +brace-bound list of elements. Each element may optionally be preceded by a corresponding key. </p> @@ -3168,35 +3169,53 @@ as a TypeName). If the LiteralType is a type parameter, all types in its type set must have the same underlying type which must be a valid composite literal type. +</p> + +<p> The types of the elements and keys must be <a href="#Assignability">assignable</a> -to the respective field, element, and key types of type <code>T</code>; +to the respective field, element, and key types of the LiteralType; there is no additional conversion. The key is interpreted as a field name for struct literals, an index for array and slice literals, and a key for map literals. -For map literals, all elements must have a key. It is an error -to specify multiple elements with the same field name or -constant key value. For non-constant map keys, see the section on -<a href="#Order_of_evaluation">evaluation order</a>. +It is an error to specify multiple elements with the same field name +or constant key value. +A literal may omit the element list; such a literal evaluates +to the zero value for its type. </p> <p> -For struct literals the following rules apply: +A parsing ambiguity arises when a composite literal using the +TypeName form of the LiteralType appears as an operand between the +<a href="#Keywords">keyword</a> and the opening brace of the block +of an "if", "for", or "switch" statement, and the composite literal +is not enclosed in parentheses, square brackets, or curly braces. +In this rare case, the opening brace of the literal is erroneously parsed +as the one introducing the block of statements. To resolve the ambiguity, +the composite literal must appear within parentheses. +</p> + +<pre> +if x == (T{a,b,c}[i]) { … } +if (x == T{a,b,c}[i]) { … } +</pre> + +<h4>Struct literals</h4> + +<p> +For struct literals without keys, the element list must contain an element +for each struct field in the order in which the fields are declared. +</p> + +<p> +For struct literals with keys the following rules apply: </p> <ul> - <li>A key must be a field name declared in the struct type. - </li> - <li>An element list that does not contain any keys must - list an element for each struct field in the - order in which the fields are declared. + <li>Every element must have a key. </li> - <li>If any element has a key, every element must have a key. + <li>Each key must be a field name declared in the struct type. </li> - <li>An element list that contains keys does not need to - have an element for each struct field. Omitted fields - get the zero value for that field. - </li> - <li>A literal may omit the element list; such a literal evaluates - to the zero value for its type. + <li>The element list does not need to have an element for each struct field. + Omitted fields get the zero value for that field. </li> <li>It is an error to specify an element for a non-exported field of a struct belonging to a different package. @@ -3220,6 +3239,8 @@ origin := Point3D{} // zero value for Point3D line := Line{origin, Point3D{y: -4, z: 12.3}} // zero value for line.q.x </pre> +<h4>Array and slice literals</h4> + <p> For array and slice literals the following rules apply: </p> @@ -3295,6 +3316,16 @@ tmp := [n]T{x1, x2, … xn} tmp[0 : n] </pre> +<h4>Map literals</h4> + +<p> +For map literals, each element must have a key. +For non-constant map keys, see the section on +<a href="#Order_of_evaluation">evaluation order</a>. +</p> + +<h4>Elision of element types</h4> + <p> Within a composite literal of array, slice, or map type <code>T</code>, elements or map keys that are themselves composite literals may elide the respective @@ -3316,22 +3347,6 @@ type PPoint *Point </pre> <p> -A parsing ambiguity arises when a composite literal using the -TypeName form of the LiteralType appears as an operand between the -<a href="#Keywords">keyword</a> and the opening brace of the block -of an "if", "for", or "switch" statement, and the composite literal -is not enclosed in parentheses, square brackets, or curly braces. -In this rare case, the opening brace of the literal is erroneously parsed -as the one introducing the block of statements. To resolve the ambiguity, -the composite literal must appear within parentheses. -</p> - -<pre> -if x == (T{a,b,c}[i]) { … } -if (x == T{a,b,c}[i]) { … } -</pre> - -<p> Examples of valid array, slice, and map literals: </p> diff --git a/doc/godebug.md b/doc/godebug.md index 184e161c40..90ed63a01a 100644 --- a/doc/godebug.md +++ b/doc/godebug.md @@ -167,8 +167,8 @@ Go 1.26 added a new `urlmaxqueryparams` setting that controls the maximum number of query parameters that net/url will accept when parsing a URL-encoded query string. If the number of parameters exceeds the number set in `urlmaxqueryparams`, parsing will fail early. The default value is `urlmaxqueryparams=10000`. -Setting `urlmaxqueryparams=0`bles the limit. To avoid denial of service attacks, -this setting and default was backported to Go 1.25.4 and Go 1.24.10. +Setting `urlmaxqueryparams=0` disables the limit. To avoid denial of service +attacks, this setting and default was backported to Go 1.25.6 and Go 1.24.12. Go 1.26 added a new `urlstrictcolons` setting that controls whether `net/url.Parse` allows malformed hostnames containing colons outside of a bracketed IPv6 address. |