Add new test.

test/libsolidity/ASTJSON/license.json

@@ -0,0 +1,35 @@
+{
+  "absolutePath": "a",
+  "exportedSymbols":
+  {
+    "C":
+    [
+      1
+    ]
+  },
+  "id": 2,
+  "license": "GPL-3.0",
+  "nodeType": "SourceUnit",
+  "nodes":
+  [
+    {
+      "abstract": false,
+      "baseContracts": [],
+      "contractDependencies": [],
+      "contractKind": "contract",
+      "documentation": null,
+      "fullyImplemented": true,
+      "id": 1,
+      "linearizedBaseContracts":
+      [
+        1
+      ],
+      "name": "C",
+      "nodeType": "ContractDefinition",
+      "nodes": [],
+      "scope": 2,
+      "src": "36:13:1"
+    }
+  ],
+  "src": "36:14:1"
+}

test/libsolidity/ASTJSON/license.sol

@@ -0,0 +1,4 @@
+// SPDX-License-Identifier: GPL-3.0
+contract C {}
+
+// ----

test/libsolidity/ASTJSON/license_legacy.json

@@ -0,0 +1,50 @@
+{
+  "attributes":
+  {
+    "absolutePath": "a",
+    "exportedSymbols":
+    {
+      "C":
+      [
+        1
+      ]
+    },
+    "license": "GPL-3.0"
+  },
+  "children":
+  [
+    {
+      "attributes":
+      {
+        "abstract": false,
+        "baseContracts":
+        [
+          null
+        ],
+        "contractDependencies":
+        [
+          null
+        ],
+        "contractKind": "contract",
+        "documentation": null,
+        "fullyImplemented": true,
+        "linearizedBaseContracts":
+        [
+          1
+        ],
+        "name": "C",
+        "nodes":
+        [
+          null
+        ],
+        "scope": 2
+      },
+      "id": 1,
+      "name": "ContractDefinition",
+      "src": "36:13:1"
+    }
+  ],
+  "id": 2,
+  "name": "SourceUnit",
+  "src": "36:14:1"
+}

test/libsolidity/StandardCompiler.cpp

@@ -1105,6 +1105,46 @@ BOOST_AUTO_TEST_CASE(metadata_without_compilation)
 	BOOST_CHECK(solidity::test::isValidMetadata(contract["metadata"].asString()));
 }
 
+
+BOOST_AUTO_TEST_CASE(license_in_metadata)
+{
+	string const input = R"(
+			{
+				"language": "Solidity",
+				"sources": {
+					"fileA": { "content": "import \"fileB\"; contract A { } // SPDX-License-Identifier: GPL-3.0 \n" },
+					"fileB": { "content": "import \"fileC\"; /* SPDX-License-Identifier: MIT */ contract B { }" },
+					"fileC": { "content": "import \"fileD\"; /* SPDX-License-Identifier: MIT AND GPL-3.0 */ contract C { }" },
+					"fileD": { "content": "// SPDX-License-Identifier: (GPL-3.0+ OR MIT) AND MIT \n import \"fileE\"; contract D { }" },
+					"fileE": { "content": "import \"fileF\"; /// SPDX-License-Identifier: MIT   \n contract E { }" },
+					"fileF": { "content": "/*\n * SPDX-License-Identifier: MIT\n */ contract F { }" }
+				},
+				"settings": {
+					"outputSelection": {
+						"fileA": {
+							"*": [ "metadata" ]
+						}
+					}
+				}
+			}
+		)";
+	Json::Value result = compile(input);
+	BOOST_CHECK(containsAtMostWarnings(result));
+	Json::Value contract = getContractResult(result, "fileA", "A");
+	BOOST_CHECK(contract.isObject());
+	BOOST_CHECK(contract["metadata"].isString());
+	Json::Value metadata;
+	BOOST_REQUIRE(util::jsonParseStrict(contract["metadata"].asString(), metadata));
+	BOOST_CHECK_EQUAL(metadata["sources"]["fileA"]["license"], "GPL-3.0");
+	BOOST_CHECK_EQUAL(metadata["sources"]["fileB"]["license"], "MIT");
+	BOOST_CHECK_EQUAL(metadata["sources"]["fileC"]["license"], "MIT AND GPL-3.0");
+	BOOST_CHECK_EQUAL(metadata["sources"]["fileD"]["license"], "(GPL-3.0+ OR MIT) AND MIT");
+	// This is actually part of the docstring, but still picked up
+	// because the source location of the contract does not cover the docstring.
+	BOOST_CHECK_EQUAL(metadata["sources"]["fileE"]["license"], "MIT");
+	BOOST_CHECK_EQUAL(metadata["sources"]["fileF"]["license"], "MIT");
+}
+
 BOOST_AUTO_TEST_CASE(common_pattern)
 {
 	char const* input = R"(

test/libsolidity/syntaxTests/license/license_double.sol

@@ -0,0 +1,5 @@
+// SPDX-License-Identifier: GPL-3.0
+contract C {}
+// SPDX-License-Identifier: MIT
+// ----
+// ParserError: Multiple SPDX license identifiers found in source file. Use "AND" or "OR" to combine multiple licenses. Please see https://spdx.org for more information.

test/libsolidity/syntaxTests/license/license_missing.sol

@@ -0,0 +1 @@
+contract C {}