Properly detect multiple licenses and validate them.

Changelog.md

@@ -22,6 +22,7 @@ Bugfixes:
  * Commandline Interface: Disallow the ``--experimental-via-ir`` option in Standard JSON, Assembler and Linker modes.
  * Opcode Optimizer: Prevent the optimizer from running multiple times to avoid potential bytecode differences for referenced code.
  * Name Resolver: Fix that when importing an aliased symbol using ``import {AliasedName} from "a.sol"`` it would use the original name of the symbol and not the aliased one.
+ * Parser: Properly check for multiple SPDX license identifiers next to each other and validate them.
  * SMTChecker: Fix false negative caused by ``push`` on storage array references returned by internal functions.
  * SMTChecker: Fix false positive in external calls from constructors.
  * SMTChecker: Fix internal error on some multi-source uses of ``abi.*``, cryptographic functions and constants.

libsolidity/parsing/Parser.cpp

@@ -34,6 +34,7 @@
 #include <libyul/backends/evm/EVMDialect.h>
 #include <boost/algorithm/string/trim.hpp>
 #include <boost/algorithm/string/replace.hpp>
+#include <boost/algorithm/string/predicate.hpp>
 #include <cctype>
 #include <vector>
 #include <regex>
@@ -2078,7 +2079,8 @@ bool Parser::variableDeclarationStart()
 optional<string> Parser::findLicenseString(std::vector<ASTPointer<ASTNode>> const& _nodes)
 {
 	// We circumvent the scanner here, because it skips non-docstring comments.
-	static regex const licenseRegex("SPDX-License-Identifier:\\s*([a-zA-Z0-9 ()+.-]+)");
+	static regex const licenseNameRegex("([a-zA-Z0-9 ()+.-]+)");
+	static regex const licenseDeclarationRegex("SPDX-License-Identifier:\\s*(.+?)([\n\r]|(\\*/))");
 
 	// Search inside all parts of the source not covered by parsed nodes.
 	// This will leave e.g. "global comments".
@@ -2093,21 +2095,33 @@ optional<string> Parser::findLicenseString(std::vector<ASTPointer<ASTNode>> cons
 			sequencesToSearch.emplace_back(source.begin() + node->location().end, source.end());
 		}
 
-	vector<string> matches;
+	vector<string> licenseNames;
 	for (auto const& [start, end]: sequencesToSearch)
 	{
-		smatch match;
-		if (regex_search(start, end, match, licenseRegex))
+		auto declarationsBegin = std::sregex_iterator(start, end, licenseDeclarationRegex);
+		auto declarationsEnd = std::sregex_iterator();
+
+		for (std::sregex_iterator declIt = declarationsBegin; declIt != declarationsEnd; ++declIt)
+			if (!declIt->empty())
 			{
-			string license{boost::trim_copy(string(match[1]))};
-			if (!license.empty())
-				matches.emplace_back(std::move(license));
+				string license = boost::trim_copy(string((*declIt)[1]));
+				licenseNames.emplace_back(std::move(license));
 			}
 	}
 
-	if (matches.size() == 1)
-		return matches.front();
-	else if (matches.empty())
+	if (licenseNames.size() == 1)
+	{
+		string const& license = licenseNames.front();
+		if (regex_match(license, licenseNameRegex))
+			return license;
+		else
+			parserError(
+				1114_error,
+				{-1, -1, m_scanner->currentLocation().sourceName},
+				"Invalid SPDX license identifier."
+			);
+	}
+	else if (licenseNames.empty())
 		parserWarning(
 			1878_error,
 			{-1, -1, m_scanner->currentLocation().sourceName},

scripts/test_antlr_grammar.sh

@@ -120,7 +120,11 @@ done < <(
       # a variable declaration.
       grep -v -E 'revertStatement/non_called.sol' |
       # Skipping a test with "let basefee := ..."
-      grep -v -E 'inlineAssembly/basefee_berlin_function.sol'
+      grep -v -E 'inlineAssembly/basefee_berlin_function.sol' |
+      # Skipping license error, unrelated to the grammar
+      grep -v -E 'license/license_double5.sol' |
+      grep -v -E 'license/license_hidden_unicode.sol' |
+      grep -v -E 'license/license_unicode.sol'
 )
 
 YUL_FILES=()

test/libsolidity/Metadata.cpp

@@ -457,28 +457,6 @@ BOOST_AUTO_TEST_CASE(metadata_license_gpl3_or_apache2)
 	BOOST_CHECK(compileAndCheckLicenseMetadata("C", sourceCode) == "GPL-3.0 OR Apache-2.0");
 }
 
-BOOST_AUTO_TEST_CASE(metadata_license_ignored_unicode)
-{
-	char const* sourceCode = R"(
-		// SPDX-License-Identifier: ⡉⡊⡋⡌⡍⡎⡏⡐⡑⡒
-		pragma solidity >=0.0;
-		contract C {
-		}
-	)";
-	BOOST_CHECK(compileAndCheckLicenseMetadata("C", sourceCode) == nullopt);
-}
-
-BOOST_AUTO_TEST_CASE(metadata_license_ignored_stray_unicode)
-{
-	char const* sourceCode = R"(
-		// SPDX-License-Identifier: GPL-3.0 ⡉⡊⡋⡌⡍⡎⡏⡐⡑⡒
-		pragma solidity >=0.0;
-		contract C {
-		}
-	)";
-	BOOST_CHECK(compileAndCheckLicenseMetadata("C", sourceCode) == "GPL-3.0");
-}
-
 BOOST_AUTO_TEST_CASE(metadata_license_bidi_marks)
 {
 	char const* sourceCode =
@@ -570,15 +548,6 @@ BOOST_AUTO_TEST_CASE(metadata_license_natspec_multiline)
 	BOOST_CHECK(compileAndCheckLicenseMetadata("C", sourceCode) == "GPL-3.0");
 }
 
-BOOST_AUTO_TEST_CASE(metadata_license_no_whitespace)
-{
-	char const* sourceCode = R"(
-		//SPDX-License-Identifier:GPL-3.0
-		contract C {}
-	)";
-	BOOST_CHECK(compileAndCheckLicenseMetadata("C", sourceCode) == "GPL-3.0");
-}
-
 BOOST_AUTO_TEST_CASE(metadata_license_no_whitespace_multiline)
 {
 	char const* sourceCode = R"(
@@ -597,6 +566,15 @@ BOOST_AUTO_TEST_CASE(metadata_license_nonempty_line)
 	BOOST_CHECK(compileAndCheckLicenseMetadata("C", sourceCode) == "GPL-3.0");
 }
 
+BOOST_AUTO_TEST_CASE(metadata_license_no_whitespace)
+{
+	char const* sourceCode = R"(
+		//SPDX-License-Identifier:GPL-3.0
+		contract C {}
+	)";
+	BOOST_CHECK(compileAndCheckLicenseMetadata("C", sourceCode) == "GPL-3.0");
+}
+
 BOOST_AUTO_TEST_SUITE_END()
 
 }

test/libsolidity/syntaxTests/license/license_AND.sol

@@ -0,0 +1,3 @@
+// SPDX-License-Identifier: GPL-3.0 AND GPL-2.0
+contract C {}
+// ----

test/libsolidity/syntaxTests/license/license_OR.sol

@@ -0,0 +1,3 @@
+// SPDX-License-Identifier: GPL-3.0 OR GPL-2.0
+contract C {}
+// ----

test/libsolidity/syntaxTests/license/license_double2.sol

@@ -0,0 +1,5 @@
+// SPDX-License-Identifier: GPL-3.0
+// SPDX-License-Identifier: MIT
+contract C {}
+// ----
+// ParserError 3716: 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_double3.sol

@@ -0,0 +1,5 @@
+// SPDX-License-Identifier: GPL-3.0
+// SPDX-License-Identifier: GPL-3.0
+contract C {}
+// ----
+// ParserError 3716: 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_double4.sol

@@ -0,0 +1,5 @@
+/* SPDX-License-Identifier: GPL-3.0 OR GPL-2.0
+SPDX-License-Identifier: GPL-3.0 OR GPL-2.0 */
+contract C {}
+// ----
+// ParserError 3716: 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_double5.sol

@@ -0,0 +1,4 @@
+/* SPDX-License-Identifier: GPL-3.0 OR GPL-2.0 */ /* SPDX-License-Identifier: GPL-3.0 OR GPL-2.0 */
+contract C {}
+// ----
+// ParserError 3716: 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_hidden_unicode.sol

@@ -1,4 +1,4 @@
-// This is parsed as GPL-3.0:
 // SPDX-License-Identifier: GPL-3.0 ⡉⡊⡋⡌⡍⡎⡏⡐⡑⡒
 contract C {}
 // ----
+// ParserError 1114: Invalid SPDX license identifier.

test/libsolidity/syntaxTests/license/license_unicode.sol

@@ -1,4 +1,4 @@
 // SPDX-License-Identifier: ⡉⡊⡋⡌⡍⡎⡏⡐⡑⡒
 contract C {}
 // ----
-// Warning 1878: SPDX license identifier not provided in source file. Before publishing, consider adding a comment containing "SPDX-License-Identifier: <SPDX-License>" to each source file. Use "SPDX-License-Identifier: UNLICENSED" for non-open-source code. Please see https://spdx.org for more information.
+// ParserError 1114: Invalid SPDX license identifier.