lsp: support setting remappings on init

support remappings in the lsp server by allowing reading the required
configuration during lsp "initialize".

the format expected is:

```
{ "remappings": [{context: "", prefix: "foo", target: "bar"}] }
```

Author: chrisfarms

Changelog.md

@@ -9,6 +9,7 @@ Compiler Features:
 * Standard JSON: Add a boolean field `settings.metadata.appendCBOR` that skips CBOR metadata from getting appended at the end of the bytecode.
 * Yul Optimizer: Allow replacing the previously hard-coded cleanup sequence by specifying custom steps after a colon delimiter (``:``) in the sequence string.
 * Language Server: Add basic document hover support.
+* Language Server: Add configuration option to apply custom remappings via ``remappings`` in the LSP settings object.
 
 
 Bugfixes:

libsolidity/lsp/FileRepository.cpp

@@ -16,6 +16,7 @@
 */
 // SPDX-License-Identifier: GPL-3.0
 
+#include <libsolidity/interface/ImportRemapper.h>
 #include <libsolidity/lsp/FileRepository.h>
 #include <libsolidity/lsp/Transport.h>
 #include <libsolidity/lsp/Utils.h>
@@ -43,9 +44,10 @@ using solidity::util::readFileAsString;
 using solidity::util::joinHumanReadable;
 using solidity::util::Result;
 
-FileRepository::FileRepository(boost::filesystem::path _basePath, std::vector<boost::filesystem::path> _includePaths):
+FileRepository::FileRepository(boost::filesystem::path _basePath, std::vector<boost::filesystem::path> _includePaths, vector<frontend::ImportRemapper::Remapping> _remappings):
 	m_basePath(std::move(_basePath)),
-	m_includePaths(std::move(_includePaths))
+	m_includePaths(std::move(_includePaths)),
+	m_remappings(std::move(_remappings))
 {
 }
 
@@ -54,6 +56,11 @@ void FileRepository::setIncludePaths(std::vector<boost::filesystem::path> _paths
 	m_includePaths = std::move(_paths);
 }
 
+void FileRepository::setRemappings(vector<frontend::ImportRemapper::Remapping> _remappings)
+{
+	m_remappings = std::move(_remappings);
+}
+
 string FileRepository::sourceUnitNameToUri(string const& _sourceUnitName) const
 {
 	regex const windowsDriveLetterPath("^[a-zA-Z]:/");

libsolidity/lsp/FileRepository.h

@@ -18,6 +18,7 @@
 #pragma once
 
 #include <libsolidity/interface/FileReader.h>
+#include <libsolidity/interface/ImportRemapper.h>
 #include <libsolutil/Result.h>
 
 #include <string>
@@ -29,11 +30,14 @@ namespace solidity::lsp
 class FileRepository
 {
 public:
-	FileRepository(boost::filesystem::path _basePath, std::vector<boost::filesystem::path> _includePaths);
+	FileRepository(boost::filesystem::path _basePath, std::vector<boost::filesystem::path> _includePaths, std::vector<frontend::ImportRemapper::Remapping> _remappings);
 
 	std::vector<boost::filesystem::path> const& includePaths() const noexcept { return m_includePaths; }
 	void setIncludePaths(std::vector<boost::filesystem::path> _paths);
 
+	std::vector<frontend::ImportRemapper::Remapping> const& remappings() const noexcept { return m_remappings; }
+	void setRemappings(std::vector<frontend::ImportRemapper::Remapping> _remappings);
+
 	boost::filesystem::path const& basePath() const { return m_basePath; }
 
 	/// Translates a compiler-internal source unit name to an LSP client path.
@@ -64,6 +68,9 @@ class FileRepository
 	/// Additional directories used for resolving relative paths in imports.
 	std::vector<boost::filesystem::path> m_includePaths;
 
+	/// Remappings of imports.
+	std::vector<frontend::ImportRemapper::Remapping> m_remappings;
+
 	/// Mapping of source unit names to their URIs as understood by the client.
 	StringMap m_sourceUnitNamesToUri;
 

libsolidity/lsp/LanguageServer.cpp

@@ -18,6 +18,7 @@
 #include <libsolidity/ast/AST.h>
 #include <libsolidity/ast/ASTUtils.h>
 #include <libsolidity/ast/ASTVisitor.h>
+#include <libsolidity/interface/ImportRemapper.h>
 #include <libsolidity/interface/ReadFile.h>
 #include <libsolidity/interface/StandardCompiler.h>
 #include <libsolidity/lsp/LanguageServer.h>
@@ -151,7 +152,7 @@ LanguageServer::LanguageServer(Transport& _transport):
 		{"textDocument/semanticTokens/full", bind(&LanguageServer::semanticTokensFull, this, _1, _2)},
 		{"workspace/didChangeConfiguration", bind(&LanguageServer::handleWorkspaceDidChangeConfiguration, this, _2)},
 	},
-	m_fileRepository("/" /* basePath */, {} /* no search paths */),
+	m_fileRepository("/" /* basePath */, {} /* no search paths */, {} /* no remappings */),
 	m_compilerStack{m_fileRepository.reader()}
 {
 }
@@ -212,6 +213,40 @@ void LanguageServer::changeConfiguration(Json::Value const& _settings)
 		if (typeFailureCount)
 			m_client.trace("Invalid JSON configuration passed. \"include-paths\" must be an array of strings.");
 	}
+
+	Json::Value jsonRemappings = _settings["remappings"];
+
+	if (jsonRemappings)
+	{
+		bool typeFailures = false;
+		if (jsonRemappings.isArray())
+		{
+			vector<frontend::ImportRemapper::Remapping> remappings;
+			for (Json::Value const& jsonPath: jsonRemappings)
+			{
+				if (
+					jsonPath.isObject() &&
+					jsonPath.get("context", "").isString() &&
+					jsonPath.get("prefix", "").isString() &&
+					jsonPath.get("target", "").isString()
+				)
+					remappings.emplace_back(ImportRemapper::Remapping{
+						jsonPath.get("context", "").asString(),
+						jsonPath.get("prefix", "").asString(),
+						jsonPath.get("target", "").asString(),
+					});
+				else
+					typeFailures = true;
+			}
+			m_fileRepository.setRemappings(std::move(remappings));
+		}
+		else
+			typeFailures = true;
+
+		if (typeFailures)
+			m_client.trace("Invalid JSON configuration passed. \"remappings\" should be of form [{\"context\":\"\", \"prefix\":\"foo\", \"target\":\"bar\"}].");
+
+	}
 }
 
 vector<boost::filesystem::path> LanguageServer::allSolidityFilesFromProject() const
@@ -237,7 +272,7 @@ void LanguageServer::compile()
 	// For files that are not open, we have to take changes on disk into account,
 	// so we just remove all non-open files.
 
-	FileRepository oldRepository(m_fileRepository.basePath(), m_fileRepository.includePaths());
+	FileRepository oldRepository(m_fileRepository.basePath(), m_fileRepository.includePaths(), m_fileRepository.remappings());
 	swap(oldRepository, m_fileRepository);
 
 	// Load all solidity files from project.
@@ -261,6 +296,7 @@ void LanguageServer::compile()
 	// TODO: optimize! do not recompile if nothing has changed (file(s) not flagged dirty).
 
 	m_compilerStack.reset(false);
+	m_compilerStack.setRemappings(m_fileRepository.remappings());
 	m_compilerStack.setSources(m_fileRepository.sourceUnits());
 	m_compilerStack.compile(CompilerStack::State::AnalysisPerformed);
 }
@@ -404,7 +440,7 @@ void LanguageServer::handleInitialize(MessageID _id, Json::Value const& _args)
 	if (_args["trace"])
 		setTrace(_args["trace"]);
 
-	m_fileRepository = FileRepository(rootPath, {});
+	m_fileRepository = FileRepository(rootPath, {}, {});
 	if (_args["initializationOptions"].isObject())
 		changeConfiguration(_args["initializationOptions"]);
 

test/lsp.py

@@ -1085,6 +1085,13 @@ def open_file_and_wait_for_diagnostics(
         )
         return self.wait_for_diagnostics(solc_process)
 
+    def expect_report(self, published_diagnostics, uri):
+        for report in published_diagnostics:
+            if report['uri'] == uri:
+                return report
+        self.expect_true(False, f"expected ${uri} in published_diagnostics")
+        return None
+
     def expect_true(
         self,
         actual,
@@ -1534,6 +1541,70 @@ def test_custom_includes(self, solc: JsonRpcProcess) -> None:
         self.expect_equal(len(diagnostics), 1, "no diagnostics")
         self.expect_diagnostic(diagnostics[0], code=2018, lineNo=5, startEndColumns=(4, 62))
 
+    def test_remapping_wrong_paramateres(self, solc: JsonRpcProcess) -> None:
+        self.setup_lsp(solc, expose_project_root=False)
+        solc.send_notification(
+            'workspace/didChangeConfiguration', {
+                'settings': {
+                    'remappings': [
+                        {
+                            'context': False,
+                            'prefix': 1,
+                            'target': f"{self.project_root_dir}/other-include-dir/otherlib/"
+                        }
+                    ]
+                }
+            }
+        )
+
+        response = solc.receive_message()
+        self.expect_equal(response["method"], "$/logTrace")
+
+        if not response["params"]["message"].startswith("Invalid JSON configuration passed."):
+            raise Exception("Expected JSON error.")
+
+    def test_remapping(self, solc: JsonRpcProcess) -> None:
+        self.setup_lsp(solc, expose_project_root=False)
+        solc.send_notification(
+            'workspace/didChangeConfiguration', {
+                'settings': {
+                    'remappings': [
+                        {
+                            'context': '',
+                            'prefix': '@other/',
+                            'target': f"{self.project_root_dir}/other-include-dir/otherlib/"
+                        }
+                    ]
+                }
+            }
+        )
+
+        # test file
+        file_with_remapped_import_uri = 'file:///remapped-include.sol'
+        solc.send_message('textDocument/didOpen', {
+            'textDocument': {
+                'uri': file_with_remapped_import_uri,
+                'languageId': 'Solidity',
+                'version': 1,
+                'text': ''.join([
+                    '// SPDX-License-Identifier: UNLICENSED\n',
+                    'pragma solidity >=0.8.0;\n',
+                    'import "@other/otherlib.sol";\n',
+                ])
+            }
+        })
+        published_diagnostics = self.wait_for_diagnostics(solc)
+        self.expect_equal(len(published_diagnostics), 2, "expected reports for two files")
+
+        report = self.expect_report(published_diagnostics, file_with_remapped_import_uri)
+        diagnostics = report['diagnostics']
+        self.expect_equal(len(diagnostics), 0, "no diagnostics")
+
+        report = self.expect_report(published_diagnostics, f"{self.project_root_uri}/other-include-dir/otherlib/otherlib.sol")
+        diagnostics = report['diagnostics']
+        self.expect_equal(len(diagnostics), 1, "no diagnostics")
+        self.expect_diagnostic(diagnostics[0], code=2018, lineNo=5, startEndColumns=(4, 62))
+
     def test_custom_includes_with_full_project(self, solc: JsonRpcProcess) -> None:
         """
         Tests loading all project files while having custom include directories configured.