Merge branch 'fromjson' (fix #464)

CONTRIBUTING.md

@@ -130,7 +130,7 @@ ronn ./man/actionlint.1.ronn
 or
 
 ```sh
-make ./man/actionlint.1
+make man
 ```
 
 ## How to develop playground

Makefile

@@ -23,7 +23,7 @@ all: build test lint
 
 t test: .testtimestamp
 
-.linttimestamp: $(TESTS) $(SRCS) $(TOOL)
+.linttimestamp: $(TESTS) $(SRCS) $(TOOL) docs/checks.md
 	go vet ./...
 	staticcheck ./...
 	GOOS=js GOARCH=wasm staticcheck ./playground

README.md

@@ -17,7 +17,7 @@ Features:
 - **Other several useful checks**; [glob syntax][filter-pattern-doc] validation, dependencies check for `needs:`,
   runner label validation, cron syntax validation, ...
 
-See [the full list][checks] of checks done by actionlint.
+See the [full list][checks] of checks done by actionlint.
 
 <img src="https://github.com/rhysd/ss/blob/master/actionlint/main.gif?raw=true" alt="actionlint reports 7 errors" width="806" height="492"/>
 
@@ -82,18 +82,6 @@ test.yaml:22:17: receiver of object dereference "permissions" must be type of ob
    |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 ```
 
-## Why?
-
-- **Running a workflow is time consuming.** You need to push the changes and wait until the workflow runs on GitHub even if
-  it contains some trivial mistakes. [act][] is useful to debug the workflow locally. But it is not suitable for CI and still
-  time consuming when your workflow gets larger.
-- **Checks of workflow files by GitHub are very loose.** It reports no error even if unexpected keys are in mappings
-  (meant that some typos in keys). And also it reports no error when accessing to property which is actually not existing.
-  For example `matrix.foo` when no `foo` is defined in `matrix:` section, it is evaluated to `null` and causes no error.
-- **Some mistakes silently break a workflow.** Most common case I saw is specifying missing property to cache key. In the
-  case cache silently does not work properly but a workflow itself runs without error. So you might not notice the mistake
-  forever.
-
 ## Quick start
 
 Install `actionlint` command by downloading [the released binary][releases] or by Homebrew or by `go install`. See
@@ -133,6 +121,8 @@ See [the usage document][usage] for more details.
 When you see some bugs or false positives, it is helpful to [file a new issue][issue-form] with a minimal example
 of input. Giving me some feedbacks like feature requests or ideas of additional checks is also welcome.
 
+See the [contribution guide](./CONTRIBUTING.md) for more details.
+
 ## License
 
 actionlint is distributed under [the MIT license](./LICENSE.txt).
@@ -145,7 +135,6 @@ actionlint is distributed under [the MIT license](./LICENSE.txt).
 [playground]: https://rhysd.github.io/actionlint/
 [shellcheck]: https://github.com/koalaman/shellcheck
 [pyflakes]: https://github.com/PyCQA/pyflakes
-[act]: https://github.com/nektos/act
 [syntax-doc]: https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions
 [filter-pattern-doc]: https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#filter-pattern-cheat-sheet
 [script-injection-doc]: https://docs.github.com/en/actions/learn-github-actions/security-hardening-for-github-actions#understanding-the-risk-of-script-injections

docs/checks.md

@@ -37,7 +37,7 @@ List of checks:
 - [Permissions](#permissions)
 - [Reusable workflows](#check-reusable-workflows)
 - [ID naming convention](#id-naming-convention)
-- [Contexts and special functions availability](#ctx-spfunc-availability)
+- [Availability of contexts and special functions](#ctx-spfunc-availability)
 - [Deprecated workflow commands](#check-deprecated-workflow-commands)
 - [Conditions always evaluated to true at `if:`](#if-cond-always-true)
 - [Action metadata syntax validation](#action-metadata-syntax)
@@ -395,8 +395,6 @@ jobs:
       # Function overloads can be handled properly. contains() has string version and array version
       - run: echo "${{ contains('hello, world', 'lo,') }}"
       - run: echo "${{ contains(github.event.labels.*.name, 'enhancement') }}"
-      # format() has a special check for formatting string
-      - run: echo "${{ format('{0}{1}', 1, 2, 3) }}"
 ```
 
 Output:
@@ -422,13 +420,9 @@ test.yaml:15:51: 2nd argument of function call is not assignable. "object" canno
    |
 15 |       - run: echo "${{ startsWith('hello, world', github.event) }}"
    |                                                   ^~~~~~~~~~~~~
-test.yaml:20:24: format string "{0}{1}" does not contain placeholder {2}. remove argument which is unused in the format string [expression]
-   |
-20 |       - run: echo "${{ format('{0}{1}', 1, 2, 3) }}"
-   |                        ^~~~~~~~~~~~~~~~
 ```
 
-[Playground](https://rhysd.github.io/actionlint/#eNqckMFOwzAQRO/9ilGF5IKciMItP8IROWHBAWe3yq4pUuR/Ry4SAqnNoScf5r3xaIU7HLLGzbv02m0AI7X6AnNmbWqe+8yWmxRqdorU6KA/FNBUsgMNUeBulgWZP1iO/DwIG30ZSnGX0LfRYu5b+iQ2vQBuK6gWZnsaLe5cpJTE4yhzenEeLol3tyhlu+rqGfk6y/9bvdpRLxBG1itG/6p/P2tT6Clpe9dymMjDEcfAA03Etl73KvMUbOeW+7Lsi/PYezx4PJ6k7wAAAP//nfWd6A==)
+[Playground](https://rhysd.github.io/actionlint/#eNqckEFKxjAQhfc9xVCEqKQ5QC/iUpI6mGo6UzoTK5TcXWJB/OFvF11l8b7v5TFMPcxZYvPBQfoGQFG0vgBLJulqnkMmzV3yNfuNRHGWnQLoKtkDDpHBPGwbZPokXul1YFL8VijFHKHvo8YcHH4hqRyAbQVF/aIvo8ZHEzEltrDykt6MBZPYmicopT115Y58zbI3q0876gX8SHJh9J/6/zOXfMAk7tmRn9CCQYqeBpyQdK/7CQAA//9h6o/Y)
 
 [Contexts][contexts-doc] and [built-in functions][funcs-doc] are strongly typed. Typos in property access of contexts and
 function names can be checked. And invalid function calls like wrong number of arguments or type mismatch at parameter also
@@ -440,11 +434,58 @@ The semantics checker can properly handle that
 - some parameters are optional (e.g. `join(strings, sep)` and `join(strings)`)
 - some parameters are repeatable (e.g. `hashFiles(file1, file2, ...)`)
 
-In addition, `format()` function has a special check for placeholders in the first parameter which represents the formatting
-string.
-
 Note that context names and function names are case-insensitive. For example, `toJSON` and `toJson` are the same function.
 
+In addition, actionlint performs special checks on some built-in functions.
+
+- `format()`: Checks placeholders in the first parameter which represents the format string.
+- `fromJSON()`: Checks the JSON string is valid and the return value is strongly typed.
+
+Example input:
+
+```yaml
+on: push
+
+jobs:
+  test:
+    # ERROR: Key 'mac' does not exist in the object returned by the fromJSON()
+    runs-on: ${{ fromJSON('{"win":"windows-latest","linux":"ubuntul-latest"}')['mac'] }}
+    steps:
+      # ERROR: {2} is missing in the first argument of format()
+      - run: echo "${{ format('{0}{1}', 1, 2, 3) }}"
+      # ERROR: Argument for {2} is missing in the arguments of format()
+      - run: echo "${{ format('{0}{1}{2}', 1, 2) }}"
+      - run: echo This is a special branch!
+        # ERROR: Broken JSON string. Special check for fromJSON()
+        if: contains(fromJson('["main","release","dev"'), github.ref_name)
+```
+
+Output:
+
+```
+test.yaml:6:18: property "mac" is not defined in object type {linux: string; win: string} [expression]
+  |
+6 |     runs-on: ${{ fromJSON('{"win":"windows-latest","linux":"ubuntul-latest"}')['mac'] }}
+  |                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+test.yaml:9:24: format string "{0}{1}" does not contain placeholder {2}. remove argument which is unused in the format string [expression]
+  |
+9 |       - run: echo "${{ format('{0}{1}', 1, 2, 3) }}"
+  |                        ^~~~~~~~~~~~~~~~
+test.yaml:11:24: format string "{0}{1}{2}" contains placeholder {2} but only 2 arguments are given to format [expression]
+   |
+11 |       - run: echo "${{ format('{0}{1}{2}', 1, 2) }}"
+   |                        ^~~~~~~~~~~~~~~~~~~
+test.yaml:14:31: broken JSON string is passed to fromJSON() at offset 23: unexpected end of JSON input [expression]
+   |
+14 |         if: contains(fromJson('["main","release","dev"'), github.ref_name)
+   |                               ^~~~~~~~~~~~~~~~~~~~~~~~~~~
+```
+
+[Playground](https://rhysd.github.io/actionlint/#eNqMj0FL9DAQhu/7K95v+CAtZMVdb/kJHvSgt0Uk7aY20k5KJnGFkP8ure5R8DJzmPeZhzewwZJl3O3eQydmByQnad1AzCz7NfC/FAwxzPdPjw+NKnTxTGad53CR/WRXhDRNnvMnGcpd5pSn66Gq9qRm26sX1Lo9luQW+XYA+9Vj4PoxgDZTiLNNjSq3tRyq0jhoHDXuWtRKf4PK8cr9Bj2PXuAFFrK43tsJXbTcj/9+soAfDPrAyXqWZmsvgRt1otl6Jk3RTc6KI01n90Gq1XjzaczdTXTDK9vZtV8BAAD//8ITaRA=)
+
+GitHub Actions does not provide the syntax to create an array or object constant. It [is popular](https://github.com/search?q=fromJSON%28%27+lang%3Ayaml&type=code)
+to create such constants via `fromJSON()`.
+
 <a id="check-contextual-step-object"></a>
 ## Contextual typing for `steps.<step_id>` objects
 
@@ -2578,7 +2619,7 @@ IDs must start with a letter or `_` and contain only alphanumeric characters, `-
 convention, and reports invalid IDs as errors.
 
 <a id="ctx-spfunc-availability"></a>
-## Contexts and special functions availability
+## Availability of contexts and special functions
 
 Example input:
 

expr_sema.go

@@ -1,6 +1,7 @@
 package actionlint
 
 import (
+	"encoding/json"
 	"fmt"
 	"strconv"
 	"strings"
@@ -794,15 +795,15 @@ func checkFuncSignature(n *FuncCallNode, sig *FuncSignature, args []ExprType) *E
 	return nil
 }
 
-func (sema *ExprSemanticsChecker) checkBuiltinFunctionCall(n *FuncCallNode, _ *FuncSignature) {
+func (sema *ExprSemanticsChecker) checkBuiltinFuncCall(n *FuncCallNode, sig *FuncSignature) ExprType {
 	sema.checkSpecialFunctionAvailability(n)
 
 	// Special checks for specific built-in functions
 	switch strings.ToLower(n.Callee) {
 	case "format":
 		lit, ok := n.Args[0].(*StringNode)
 		if !ok {
-			return
+			return sig.Ret
 		}
 		l := len(n.Args) - 1 // -1 means removing first format string argument
 
@@ -819,7 +820,22 @@ func (sema *ExprSemanticsChecker) checkBuiltinFunctionCall(n *FuncCallNode, _ *F
 		for i := range holders {
 			sema.errorf(n, "format string %q contains placeholder {%d} but only %d arguments are given to format", lit.Value, i, l)
 		}
+	case "fromjson":
+		lit, ok := n.Args[0].(*StringNode)
+		if !ok {
+			return sig.Ret
+		}
+		var v any
+		err := json.Unmarshal([]byte(lit.Value), &v)
+		if err == nil {
+			return typeOfJSONValue(v)
+		}
+		if s, ok := err.(*json.SyntaxError); ok {
+			sema.errorf(lit, "broken JSON string is passed to fromJSON() at offset %d: %s", s.Offset, s)
+		}
 	}
+
+	return sig.Ret
 }
 
 func (sema *ExprSemanticsChecker) checkFuncCall(n *FuncCallNode) ExprType {
@@ -846,8 +862,7 @@ func (sema *ExprSemanticsChecker) checkFuncCall(n *FuncCallNode) ExprType {
 		err := checkFuncSignature(n, sig, tys)
 		if err == nil {
 			// When one of overload pass type check, overload was resolved correctly
-			sema.checkBuiltinFunctionCall(n, sig)
-			return sig.Ret
+			return sema.checkBuiltinFuncCall(n, sig)
 		}
 		errs = append(errs, err)
 	}

expr_sema_test.go

@@ -637,8 +637,8 @@ func TestExprSemanticsCheckOK(t *testing.T) {
 		},
 		{
 			what:         "non-special function",
-			input:        "fromJSON('{}')",
-			expected:     AnyType{},
+			input:        "contains('hello, world', 'o, w')",
+			expected:     BoolType{},
 			availSPFuncs: []string{"always"},
 		},
 		{
@@ -729,6 +729,15 @@ func TestExprSemanticsCheckOK(t *testing.T) {
 			input:    "format('hello {{{0}', 'world')", // First {{ is escaped. {0} is not escaped
 			expected: StringType{},
 		},
+		{
+			what:  "fromJSON with JSON constant value",
+			input: `fromJSON('{"foo":true,"bar":["foo", 12.3],"piyo":null}')`,
+			expected: NewStrictObjectType(map[string]ExprType{
+				"foo":  BoolType{},
+				"bar":  &ArrayType{Elem: StringType{}}, // Element type was merged
+				"piyo": NullType{},
+			}),
+		},
 	}
 
 	allSPFuncs := []string{}
@@ -1255,6 +1264,13 @@ func TestExprSemanticsCheckError(t *testing.T) {
 				"must not start with the GITHUB_ prefix",
 			},
 		},
+		{
+			what:  "broken JSON value at fromJSON argument",
+			input: `fromJSON('{"foo": true')`,
+			expected: []string{
+				"broken JSON string is passed to fromJSON() at offset 12",
+			},
+		},
 	}
 
 	allSP := []string{}

expr_type.go

@@ -427,3 +427,48 @@ func (ty *ArrayType) DeepCopy() ExprType {
 func EqualTypes(l, r ExprType) bool {
 	return l.Assignable(r) && r.Assignable(l)
 }
+
+// typeOfJSONValue returns the type of the given JSON value. The JSON value is an any value decoded by json.Unmarshal.
+// https://pkg.go.dev/encoding/json#Unmarshal
+//
+// To unmarshal JSON into an interface value, Unmarshal stores one of these in the interface value:
+//   - bool, for JSON booleans
+//   - float64, for JSON numbers
+//   - string, for JSON strings
+//   - []interface{}, for JSON arrays
+//   - map[string]interface{}, for JSON objects
+//   - nil for JSON null
+func typeOfJSONValue(v any) ExprType {
+	switch v := v.(type) {
+	case bool:
+		return BoolType{}
+	case float64:
+		return NumberType{}
+	case string:
+		return StringType{}
+	case []any:
+		var elem ExprType
+		for _, e := range v {
+			t := typeOfJSONValue(e)
+			if elem == nil {
+				elem = t
+			} else {
+				elem = elem.Merge(t)
+			}
+		}
+		if elem == nil {
+			elem = AnyType{}
+		}
+		return &ArrayType{Elem: elem}
+	case map[string]any:
+		props := make(map[string]ExprType, len(v))
+		for k, v := range v {
+			props[k] = typeOfJSONValue(v)
+		}
+		return NewStrictObjectType(props)
+	case nil:
+		return NullType{}
+	default:
+		panic(v) // Unreachable
+	}
+}