Distinguish between ternary's : and arrow fn's return type (#596)

test/fixtures/flow/regression/issue-58-ambiguous/actual.js

@@ -0,0 +1,4 @@
+// This can be parsed in two ways:
+// a ? b : (c => ((d): e => f))
+// a ? ((b): c => d) : (e => f)
+a ? (b) : c => (d) : e => f;

test/fixtures/flow/regression/issue-58-ambiguous/options.json

@@ -0,0 +1,3 @@
+{
+    "throws": "Ambiguous expression: wrap the arrow functions in parentheses to disambiguate. (4:4)"
+}

test/fixtures/flow/regression/issue-58-failing-1/actual.js

@@ -0,0 +1,2 @@
+// Function which looks like a return type
+a ? (b) : (c => d) => e;

test/fixtures/flow/regression/issue-58-failing-1/options.json

@@ -0,0 +1,3 @@
+{
+    "throws": "Invalid left-hand side in arrow function parameters (2:11)"
+}

test/fixtures/flow/regression/issue-58-failing-2/actual.js

@@ -0,0 +1,2 @@
+// Invalid LHS parameter after type parameters
+a ? <T>(b => c) : d => (e) : f => g;

test/fixtures/flow/regression/issue-58-failing-2/options.json

@@ -0,0 +1,3 @@
+{
+    "throws": "Invalid left-hand side in arrow function parameters (2:8)"
+}

test/fixtures/flow/regression/issue-58-failing-3/actual.js

@@ -0,0 +1,2 @@
+// Invalid LHS parameter after type parameters
+a ? (b => c) => (e) : f => g;

test/fixtures/flow/regression/issue-58-failing-3/options.json

@@ -0,0 +1,3 @@
+{
+    "throws": "Invalid left-hand side in arrow function parameters (2:5)"
+}

test/fixtures/flow/regression/issue-58-failing-4/actual.js

@@ -0,0 +1,2 @@
+// Invalid LHS parameter
+a ? async (b => c) => (d) : f => g;

test/fixtures/flow/regression/issue-58-failing-4/options.json

@@ -0,0 +1,3 @@
+{
+    "throws": "Invalid left-hand side in arrow function parameters (2:11)"
+}

test/fixtures/flow/regression/issue-58/actual.js

@@ -0,0 +1,44 @@
+// Valid lhs value inside parentheses
+a ? (b) : c => d; // a ? b : (c => d)
+a ? (b) : c => d : e; // a ? ((b): c => d) : e
+a ? (b) : (c) : d => e; // a ? b : ((c): d => e)
+
+// Nested arrow function inside parentheses
+a ? (b = (c) => d) : e => f; // a ? (b = (c) => d) : (e => f)
+a ? (b = (c) => d) : e => f : g; // a ? ((b = (c) => d): e => f) : g
+
+// Nested conditional expressions
+    b ? c ? (d) : e => (f) : g : h; // b ? (c ? ((d): e => f) : g) : h
+a ? b ? c ? (d) : e => (f) : g : h; // a ? (b ? (c ? d : (e => f)) : g) : h
+
+a ? b ? (c) : (d) : (e) => f : g; // a ? (b ? c : ((d): e => f)) : g
+
+// Multiple arrow functions
+a ? (b) : c => d : (e) : f => g; // a ? ((b): c => d) : ((e): f => g)
+
+// Multiple nested arrow functions (<T> is needed to avoid ambiguities)
+a ? (b) : c => (d) : e => f : g; // a ? ((b): c => ((d): e => f)) : g
+a ? (b) : c => <T>(d) : e => f; // a ? b : (c => (<T>(d): e => f))
+a ? <T>(b) : c => (d) : e => f; // a ? (<T>(b): c => d) : (e => f)
+
+// Invalid lhs value inside parentheses
+a ? (b => c) : d => e; // a ? (b => c) : (d => e)
+a ? b ? (c => d) : e => f : g; // a ? (b ? (c => d) : (e => f)) : g
+
+// Invalid lhs value inside parentheses inside arrow function
+a ? (b) : c => (d => e) : f => g; // a ? ((b): c => (d => e)) : (f => g)
+a ? b ? (c => d) : e => (f => g) : h => i; // a ? (b ? (c => d) : (e => (f => g))) : (h => i)
+
+// Function as type annotation
+a ? (b) : (c => d) => e : f; // a ? ((b): (c => d) => e) : f
+
+// Async functions or calls
+a ? async (b) : c => d; // a ? (async(b)) : (c => d)
+a ? async (b) : c => d : e; // a ? (async (b): c => d) : e
+a ? async (b => c) : d => e; // a ? (async(b => c)) : (d => e)
+a ? async (b) => (c => d) : e => f; // a ? (async (b) => c => d) : (e => f)
+
+// https://github.com/prettier/prettier/issues/2194
+let icecream = what == "cone"
+  ? p => (!!p ? `here's your ${p} cone` : `just the empty cone for you`)
+  : p => `here's your ${p} ${what}`;