Match more SPDX-License-Identifer lines

Changelog.md

@@ -6,6 +6,7 @@ Language Features:
 
 
 Compiler Features:
+ * Parser: Extend parsing rule for ``SPDX-License-Identifier``.
  * SMTChecker: Function definitions can be annotated with the custom Natspec tag ``custom:smtchecker abstract-function-nondet`` to be abstracted by a nondeterministic value when called.
  * Standard JSON / combined JSON: New artifact "functionDebugData" that contains bytecode offsets of entry points of functions and potentially more information in the future.
  * Yul Optimizer: Evaluate ``keccak256(a, c)``, when the value at memory location ``a`` is known at compile time and ``c`` is a constant ``<= 32``.
@@ -47,7 +48,6 @@ Compiler Features:
  * Yul EVM Code Transform: Stack Optimization: Reuse slots of unused function arguments and defer allocating stack slots for return variables until after expression statements and assignments that do not reference them.
  * Yul Optimizer: Added a new step FunctionSpecializer, that specializes a function with its literal arguments.
 
-
 Bugfixes:
  * Antlr Grammar: Fix parsing of import paths involving properly distinguishing between empty and non-empty string literals in general.
  * AST Output: Fix ``kind`` field of ``ModifierInvocation`` for base constructor calls.
@@ -100,7 +100,6 @@ Compiler Features:
  * Optimizer: Simple inlining when jumping to small blocks that jump again after a few side-effect free opcodes.
  * NatSpec: Allow and export all tags that start with ``@custom:``.
 
-
 Bugfixes:
  * AST: Added ``referencedDeclaration`` for enum members.
  * Code Generator: Fix internal error when functions are passed as parameters of other callables, when the function types can be implicitly converted, but not identical.

libsolidity/parsing/Parser.cpp

@@ -2052,7 +2052,10 @@ 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 ()+.-]+)");
+	// This matches the entire line starting with the SPDX-License-Identifier.
+	static regex const licenseLineRegex("SPDX-License-Identifier:\\s*([^\n])\\s*(\\*/)?");
+	// This is the actual allowed format for the license tag.
+	static regex const licenseRegex("^([a-zA-Z0-9 ()+.-]*)$");
 
 	// Search inside all parts of the source not covered by parsed nodes.
 	// This will leave e.g. "global comments".
@@ -2070,12 +2073,26 @@ optional<string> Parser::findLicenseString(std::vector<ASTPointer<ASTNode>> cons
 	vector<string> matches;
 	for (auto const& [start, end]: sequencesToSearch)
 	{
-		smatch match;
-		if (regex_search(start, end, match, licenseRegex))
+		smatch lineMatch;
+		if (regex_search(start, end, lineMatch, licenseLineRegex))
 		{
-			string license{boost::trim_copy(string(match[1]))};
-			if (!license.empty())
-				matches.emplace_back(std::move(license));
+			string license{boost::trim_copy(string(lineMatch[1]))};
+			smatch licenseMatch;
+			if (regex_search(license, licenseMatch, licenseRegex))
+			{
+				license = string(licenseMatch[1]);
+				if (!license.empty())
+					matches.emplace_back(std::move(license));
+			}
+			else
+			{
+				parserError(
+					5406_error,
+					{-1, -1, m_scanner->charStream()},
+					"SPDX license identifier is ill-formatted. "
+					"Please see https://spdx.org for more information."
+				);
+			}
 		}
 	}
 

test/libsolidity/syntaxTests/license/license_double.sol

@@ -2,4 +2,4 @@
 contract C {}
 // SPDX-License-Identifier: MIT
 // ----
-// 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.
+// 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.

test/libsolidity/syntaxTests/license/license_missing.sol

@@ -1,3 +1,4 @@
 // This test is actually useless, as the test suite adds the automatic preamble.
 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.