tools/versioner/src/DeclarationDatabase.cpp - platform/bionic.git - Git at Google

 /*
  * Copyright (C) 2016 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #include "DeclarationDatabase.h"

 #include <err.h>

 #include <iostream>
 #include <map>
 #include <mutex>
 #include <set>
 #include <sstream>
 #include <string>
 #include <utility>

 #include <clang/AST/AST.h>
 #include <clang/AST/Attr.h>
 #include <clang/AST/Mangle.h>
 #include <clang/AST/RecursiveASTVisitor.h>
 #include <clang/Frontend/ASTUnit.h>
 #include <llvm/Support/raw_ostream.h>

 using namespace clang;

 static bool shouldMangle(MangleContext* mangler, NamedDecl* decl) {
   // Passing a decl with static linkage to the mangler gives incorrect results.
   // Check some things ourselves before handing it off to the mangler.
   if (auto FD = dyn_cast<FunctionDecl>(decl)) {
     if (FD->isExternC()) {
       return false;
     }

     if (FD->isInExternCContext()) {
       return false;
     }
   }

   return mangler->shouldMangleDeclName(decl);
 }

 class Visitor : public RecursiveASTVisitor<Visitor> {
   HeaderDatabase& database;
   CompilationType type;
   SourceManager& src_manager;
   std::unique_ptr<MangleContext> mangler;

  public:
   Visitor(HeaderDatabase& database, CompilationType type, ASTContext& ctx)
       : database(database), type(type), src_manager(ctx.getSourceManager()) {
     mangler.reset(ItaniumMangleContext::create(ctx, ctx.getDiagnostics()));
   }

   std::string getDeclName(NamedDecl* decl) {
     if (auto var_decl = dyn_cast<VarDecl>(decl)) {
       if (!var_decl->isFileVarDecl()) {
         return "<local var>";
       }
     }

     // <math.h> maps fool onto foo on 32-bit, since long double is the same as double.
     if (auto asm_attr = decl->getAttr<AsmLabelAttr>()) {
       return asm_attr->getLabel().str();
     }

     // The decl might not have a name (e.g. bitfields).
     if (auto identifier = decl->getIdentifier()) {
       if (shouldMangle(mangler.get(), decl)) {
         std::string mangled;
         llvm::raw_string_ostream ss(mangled);
         mangler->mangleName(decl, ss);
         return mangled;
       }

       return identifier->getName().str();
     }

     return "<unnamed>";
   }

   bool VisitDeclaratorDecl(DeclaratorDecl* decl, SourceRange range) {
     // Skip declarations inside of functions (function arguments, variable declarations inside of
     // inline functions, etc).
     if (decl->getParentFunctionOrMethod()) {
       return true;
     }

     auto named_decl = dyn_cast<NamedDecl>(decl);
     if (!named_decl) {
       return true;
     }

     std::string declaration_name = getDeclName(named_decl);
     bool is_extern = named_decl->getFormalLinkage() == ExternalLinkage;
     bool is_definition = false;
     bool no_guard = false;
     bool fortify_inline = false;

     if (auto function_decl = dyn_cast<FunctionDecl>(decl)) {
       is_definition = function_decl->isThisDeclarationADefinition();
     } else if (auto var_decl = dyn_cast<VarDecl>(decl)) {
       if (!var_decl->isFileVarDecl()) {
         return true;
       }

       switch (var_decl->isThisDeclarationADefinition()) {
         case VarDecl::DeclarationOnly:
           is_definition = false;
           break;

         case VarDecl::Definition:
           is_definition = true;
           break;

         case VarDecl::TentativeDefinition:
           // Forbid tentative definitions in headers.
           fprintf(stderr, "ERROR: declaration '%s' is a tentative definition\n",
                   declaration_name.c_str());
           decl->dump();
           abort();
       }
     } else {
       // We only care about function and variable declarations.
       return true;
     }

     if (decl->hasAttr<UnavailableAttr>()) {
       // Skip declarations that exist only for compile-time diagnostics.
       return true;
     }

     DeclarationAvailability availability;

     // Find and parse __ANDROID_AVAILABILITY_DUMP__ annotations.
     for (const AnnotateAttr* attr : decl->specific_attrs<AnnotateAttr>()) {
       llvm::StringRef annotation = attr->getAnnotation();
       if (annotation == "versioner_no_guard") {
         no_guard = true;
       } else if (annotation == "versioner_fortify_inline") {
         fortify_inline = true;
       } else {
         llvm::SmallVector<llvm::StringRef, 2> fragments;
         annotation.split(fragments, "=");
         if (fragments.size() != 2) {
           continue;
         }

         auto& global_availability = availability.global_availability;
         auto& arch_availability = availability.arch_availability;
         std::map<std::string, std::vector<int*>> prefix_map = {
           { "introduced_in", { &global_availability.introduced } },
           { "deprecated_in", { &global_availability.deprecated } },
           { "obsoleted_in", { &global_availability.obsoleted } },
           { "introduced_in_arm", { &arch_availability[Arch::arm].introduced } },
           { "introduced_in_x86", { &arch_availability[Arch::x86].introduced } },
           { "introduced_in_32",
             { &arch_availability[Arch::arm].introduced,
               &arch_availability[Arch::x86].introduced } },
           { "introduced_in_64",
             { &arch_availability[Arch::arm64].introduced,
               &arch_availability[Arch::riscv64].introduced,
               &arch_availability[Arch::x86_64].introduced } },
         };

         if (auto it = prefix_map.find(fragments[0].str()); it != prefix_map.end()) {
           int value;
           if (fragments[1].getAsInteger(10, value)) {
             errx(1, "invalid __ANDROID_AVAILABILITY_DUMP__ annotation: '%s'",
                  annotation.str().c_str());
           }

           for (int* ptr : it->second) {
             *ptr = value;
           }
         }
       }
     }

     auto symbol_it = database.symbols.find(declaration_name);
     if (symbol_it == database.symbols.end()) {
       Symbol symbol = {.name = declaration_name };
       bool unused;
       std::tie(symbol_it, unused) = database.symbols.insert({declaration_name, symbol});
     }

     auto expansion_range = src_manager.getExpansionRange(range);
     auto filename = src_manager.getFilename(expansion_range.getBegin());
     if (filename != src_manager.getFilename(expansion_range.getEnd())) {
       errx(1, "expansion range filenames don't match");
     }

     Location location = {
       .filename = filename.str(),
       .start = {
         .line = src_manager.getExpansionLineNumber(expansion_range.getBegin()),
         .column = src_manager.getExpansionColumnNumber(expansion_range.getBegin()),
       },
       .end = {
         .line = src_manager.getExpansionLineNumber(expansion_range.getEnd()),
         .column = src_manager.getExpansionColumnNumber(expansion_range.getEnd()),
       }
     };

     // Find or insert an entry for the declaration.
     if (auto declaration_it = symbol_it->second.declarations.find(location);
         declaration_it != symbol_it->second.declarations.end()) {
       if (declaration_it->second.is_extern != is_extern ||
           declaration_it->second.is_definition != is_definition ||
           declaration_it->second.no_guard != no_guard ||
           declaration_it->second.fortify_inline != fortify_inline) {
         errx(1, "varying declaration of '%s' at %s:%u:%u", declaration_name.c_str(),
              location.filename.c_str(), location.start.line, location.start.column);
       }
       declaration_it->second.availability.insert(std::make_pair(type, availability));
     } else {
       Declaration declaration;
       declaration.name = declaration_name;
       declaration.location = location;
       declaration.is_extern = is_extern;
       declaration.is_definition = is_definition;
       declaration.no_guard = no_guard;
       declaration.fortify_inline = fortify_inline;
       declaration.availability.insert(std::make_pair(type, availability));
       symbol_it->second.declarations.insert(std::make_pair(location, declaration));
     }

     return true;
   }

   bool VisitDeclaratorDecl(DeclaratorDecl* decl) {
     return VisitDeclaratorDecl(decl, decl->getSourceRange());
   }

   bool TraverseLinkageSpecDecl(LinkageSpecDecl* decl) {
     // Make sure that we correctly calculate the SourceRange of a declaration that has a non-braced
     // extern "C"/"C++".
     if (!decl->hasBraces()) {
       DeclaratorDecl* child = nullptr;
       for (auto child_decl : decl->decls()) {
         if (child != nullptr) {
           errx(1, "LinkageSpecDecl has multiple children");
         }

         if (DeclaratorDecl* declarator_decl = dyn_cast<DeclaratorDecl>(child_decl)) {
           child = declarator_decl;
         } else {
           errx(1, "child of LinkageSpecDecl is not a DeclaratorDecl");
         }
       }

       return VisitDeclaratorDecl(child, decl->getSourceRange());
     }

     for (auto child : decl->decls()) {
       if (!TraverseDecl(child)) {
         return false;
       }
     }
     return true;
   }
 };

 bool DeclarationAvailability::merge(const DeclarationAvailability& other) {
 #define check_avail(expr) error |= (!this->expr.empty() && this->expr != other.expr);
   bool error = false;

   if (!other.global_availability.empty()) {
     check_avail(global_availability);
     this->global_availability = other.global_availability;
   }

   for (Arch arch : supported_archs) {
     if (!other.arch_availability[arch].empty()) {
       check_avail(arch_availability[arch]);
       this->arch_availability[arch] = other.arch_availability[arch];
     }
   }
 #undef check_avail

   return !error;
 }

 bool Declaration::calculateAvailability(DeclarationAvailability* output) const {
   DeclarationAvailability avail;
   for (const auto& it : this->availability) {
     if (!avail.merge(it.second)) {
       return false;
     }
   }
   *output = avail;
   return true;
 }

 bool Symbol::calculateAvailability(DeclarationAvailability* output) const {
   DeclarationAvailability avail;
   for (const auto& it : this->declarations) {
     // Don't merge availability for inline functions (because they shouldn't have any).
     if (it.second.is_definition) {
       continue;
     }

     DeclarationAvailability decl_availability;
     if (!it.second.calculateAvailability(&decl_availability)) {
       return false;
       abort();
     }

     if (!avail.merge(decl_availability)) {
       return false;
     }
   }
   *output = avail;
   return true;
 }

 bool Symbol::hasDeclaration(const CompilationType& type) const {
   for (const auto& decl_it : this->declarations) {
     for (const auto& compilation_it : decl_it.second.availability) {
       if (compilation_it.first == type) {
         return true;
       }
     }
   }
   return false;
 }

 void HeaderDatabase::parseAST(CompilationType type, ASTContext& ctx) {
   std::unique_lock<std::mutex> lock(this->mutex);
   Visitor visitor(*this, type, ctx);
   visitor.TraverseDecl(ctx.getTranslationUnitDecl());
 }

 std::string to_string(const AvailabilityValues& av) {
   std::stringstream ss;

   if (av.introduced != 0) {
     ss << "introduced = " << av.introduced << ", ";
   }

   if (av.deprecated != 0) {
     ss << "deprecated = " << av.deprecated << ", ";
   }

   if (av.obsoleted != 0) {
     ss << "obsoleted = " << av.obsoleted << ", ";
   }

   std::string result = ss.str();
   if (!result.empty()) {
     result = result.substr(0, result.length() - 2);
   }
   return result;
 }

 std::string to_string(const DeclarationType& type) {
   switch (type) {
     case DeclarationType::function:
       return "function";
     case DeclarationType::variable:
       return "variable";
     case DeclarationType::inconsistent:
       return "inconsistent";
   }
   abort();
 }

 std::string to_string(const DeclarationAvailability& decl_av) {
   std::stringstream ss;
   if (!decl_av.global_availability.empty()) {
     ss << to_string(decl_av.global_availability) << ", ";
   }

   for (const auto& it : decl_av.arch_availability) {
     if (!it.second.empty()) {
       ss << to_string(it.first) << ": " << to_string(it.second) << ", ";
     }
   }

   std::string result = ss.str();
   if (result.size() == 0) {
     return "no availability";
   }

   return result.substr(0, result.length() - 2);
 }

 std::string to_string(const Location& loc) {
   std::stringstream ss;
   ss << loc.filename << ":" << loc.start.line << ":" << loc.start.column;
   return ss.str();
 }
	/*
	* Copyright (C) 2016 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#include "DeclarationDatabase.h"

	#include <err.h>

	#include <iostream>
	#include <map>
	#include <mutex>
	#include <set>
	#include <sstream>
	#include <string>
	#include <utility>

	#include <clang/AST/AST.h>
	#include <clang/AST/Attr.h>
	#include <clang/AST/Mangle.h>
	#include <clang/AST/RecursiveASTVisitor.h>
	#include <clang/Frontend/ASTUnit.h>
	#include <llvm/Support/raw_ostream.h>

	using namespace clang;

	static bool shouldMangle(MangleContext* mangler, NamedDecl* decl) {
	// Passing a decl with static linkage to the mangler gives incorrect results.
	// Check some things ourselves before handing it off to the mangler.
	if (auto FD = dyn_cast<FunctionDecl>(decl)) {
	if (FD->isExternC()) {
	return false;
	}

	if (FD->isInExternCContext()) {
	return false;
	}
	}

	return mangler->shouldMangleDeclName(decl);
	}

	class Visitor : public RecursiveASTVisitor<Visitor> {
	HeaderDatabase& database;
	CompilationType type;
	SourceManager& src_manager;
	std::unique_ptr<MangleContext> mangler;

	public:
	Visitor(HeaderDatabase& database, CompilationType type, ASTContext& ctx)
	: database(database), type(type), src_manager(ctx.getSourceManager()) {
	mangler.reset(ItaniumMangleContext::create(ctx, ctx.getDiagnostics()));
	}

	std::string getDeclName(NamedDecl* decl) {
	if (auto var_decl = dyn_cast<VarDecl>(decl)) {
	if (!var_decl->isFileVarDecl()) {
	return "<local var>";
	}
	}

	// <math.h> maps fool onto foo on 32-bit, since long double is the same as double.
	if (auto asm_attr = decl->getAttr<AsmLabelAttr>()) {
	return asm_attr->getLabel().str();
	}

	// The decl might not have a name (e.g. bitfields).
	if (auto identifier = decl->getIdentifier()) {
	if (shouldMangle(mangler.get(), decl)) {
	std::string mangled;
	llvm::raw_string_ostream ss(mangled);
	mangler->mangleName(decl, ss);
	return mangled;
	}

	return identifier->getName().str();
	}

	return "<unnamed>";
	}

	bool VisitDeclaratorDecl(DeclaratorDecl* decl, SourceRange range) {
	// Skip declarations inside of functions (function arguments, variable declarations inside of
	// inline functions, etc).
	if (decl->getParentFunctionOrMethod()) {
	return true;
	}

	auto named_decl = dyn_cast<NamedDecl>(decl);
	if (!named_decl) {
	return true;
	}

	std::string declaration_name = getDeclName(named_decl);
	bool is_extern = named_decl->getFormalLinkage() == ExternalLinkage;
	bool is_definition = false;
	bool no_guard = false;
	bool fortify_inline = false;

	if (auto function_decl = dyn_cast<FunctionDecl>(decl)) {
	is_definition = function_decl->isThisDeclarationADefinition();
	} else if (auto var_decl = dyn_cast<VarDecl>(decl)) {
	if (!var_decl->isFileVarDecl()) {
	return true;
	}

	switch (var_decl->isThisDeclarationADefinition()) {
	case VarDecl::DeclarationOnly:
	is_definition = false;
	break;

	case VarDecl::Definition:
	is_definition = true;
	break;

	case VarDecl::TentativeDefinition:
	// Forbid tentative definitions in headers.
	fprintf(stderr, "ERROR: declaration '%s' is a tentative definition\n",
	declaration_name.c_str());
	decl->dump();
	abort();
	}
	} else {
	// We only care about function and variable declarations.
	return true;
	}

	if (decl->hasAttr<UnavailableAttr>()) {
	// Skip declarations that exist only for compile-time diagnostics.
	return true;
	}

	DeclarationAvailability availability;

	// Find and parse __ANDROID_AVAILABILITY_DUMP__ annotations.
	for (const AnnotateAttr* attr : decl->specific_attrs<AnnotateAttr>()) {
	llvm::StringRef annotation = attr->getAnnotation();
	if (annotation == "versioner_no_guard") {
	no_guard = true;
	} else if (annotation == "versioner_fortify_inline") {
	fortify_inline = true;
	} else {
	llvm::SmallVector<llvm::StringRef, 2> fragments;
	annotation.split(fragments, "=");
	if (fragments.size() != 2) {
	continue;
	}

	auto& global_availability = availability.global_availability;
	auto& arch_availability = availability.arch_availability;
	std::map<std::string, std::vector<int*>> prefix_map = {
	{ "introduced_in", { &global_availability.introduced } },
	{ "deprecated_in", { &global_availability.deprecated } },
	{ "obsoleted_in", { &global_availability.obsoleted } },
	{ "introduced_in_arm", { &arch_availability[Arch::arm].introduced } },
	{ "introduced_in_x86", { &arch_availability[Arch::x86].introduced } },
	{ "introduced_in_32",
	{ &arch_availability[Arch::arm].introduced,
	&arch_availability[Arch::x86].introduced } },
	{ "introduced_in_64",
	{ &arch_availability[Arch::arm64].introduced,
	&arch_availability[Arch::riscv64].introduced,
	&arch_availability[Arch::x86_64].introduced } },
	};

	if (auto it = prefix_map.find(fragments[0].str()); it != prefix_map.end()) {
	int value;
	if (fragments[1].getAsInteger(10, value)) {
	errx(1, "invalid __ANDROID_AVAILABILITY_DUMP__ annotation: '%s'",
	annotation.str().c_str());
	}

	for (int* ptr : it->second) {
	*ptr = value;
	}
	}
	}
	}

	auto symbol_it = database.symbols.find(declaration_name);
	if (symbol_it == database.symbols.end()) {
	Symbol symbol = {.name = declaration_name };
	bool unused;
	std::tie(symbol_it, unused) = database.symbols.insert({declaration_name, symbol});
	}

	auto expansion_range = src_manager.getExpansionRange(range);
	auto filename = src_manager.getFilename(expansion_range.getBegin());
	if (filename != src_manager.getFilename(expansion_range.getEnd())) {
	errx(1, "expansion range filenames don't match");
	}

	Location location = {
	.filename = filename.str(),
	.start = {
	.line = src_manager.getExpansionLineNumber(expansion_range.getBegin()),
	.column = src_manager.getExpansionColumnNumber(expansion_range.getBegin()),
	},
	.end = {
	.line = src_manager.getExpansionLineNumber(expansion_range.getEnd()),
	.column = src_manager.getExpansionColumnNumber(expansion_range.getEnd()),
	}
	};

	// Find or insert an entry for the declaration.
	if (auto declaration_it = symbol_it->second.declarations.find(location);
	declaration_it != symbol_it->second.declarations.end()) {
	if (declaration_it->second.is_extern != is_extern \|\|
	declaration_it->second.is_definition != is_definition \|\|
	declaration_it->second.no_guard != no_guard \|\|
	declaration_it->second.fortify_inline != fortify_inline) {
	errx(1, "varying declaration of '%s' at %s:%u:%u", declaration_name.c_str(),
	location.filename.c_str(), location.start.line, location.start.column);
	}
	declaration_it->second.availability.insert(std::make_pair(type, availability));
	} else {
	Declaration declaration;
	declaration.name = declaration_name;
	declaration.location = location;
	declaration.is_extern = is_extern;
	declaration.is_definition = is_definition;
	declaration.no_guard = no_guard;
	declaration.fortify_inline = fortify_inline;
	declaration.availability.insert(std::make_pair(type, availability));
	symbol_it->second.declarations.insert(std::make_pair(location, declaration));
	}

	return true;
	}

	bool VisitDeclaratorDecl(DeclaratorDecl* decl) {
	return VisitDeclaratorDecl(decl, decl->getSourceRange());
	}

	bool TraverseLinkageSpecDecl(LinkageSpecDecl* decl) {
	// Make sure that we correctly calculate the SourceRange of a declaration that has a non-braced
	// extern "C"/"C++".
	if (!decl->hasBraces()) {
	DeclaratorDecl* child = nullptr;
	for (auto child_decl : decl->decls()) {
	if (child != nullptr) {
	errx(1, "LinkageSpecDecl has multiple children");
	}

	if (DeclaratorDecl* declarator_decl = dyn_cast<DeclaratorDecl>(child_decl)) {
	child = declarator_decl;
	} else {
	errx(1, "child of LinkageSpecDecl is not a DeclaratorDecl");
	}
	}

	return VisitDeclaratorDecl(child, decl->getSourceRange());
	}

	for (auto child : decl->decls()) {
	if (!TraverseDecl(child)) {
	return false;
	}
	}
	return true;
	}
	};

	bool DeclarationAvailability::merge(const DeclarationAvailability& other) {
	#define check_avail(expr) error \|= (!this->expr.empty() && this->expr != other.expr);
	bool error = false;

	if (!other.global_availability.empty()) {
	check_avail(global_availability);
	this->global_availability = other.global_availability;
	}

	for (Arch arch : supported_archs) {
	if (!other.arch_availability[arch].empty()) {
	check_avail(arch_availability[arch]);
	this->arch_availability[arch] = other.arch_availability[arch];
	}
	}
	#undef check_avail

	return !error;
	}

	bool Declaration::calculateAvailability(DeclarationAvailability* output) const {
	DeclarationAvailability avail;
	for (const auto& it : this->availability) {
	if (!avail.merge(it.second)) {
	return false;
	}
	}
	*output = avail;
	return true;
	}

	bool Symbol::calculateAvailability(DeclarationAvailability* output) const {
	DeclarationAvailability avail;
	for (const auto& it : this->declarations) {
	// Don't merge availability for inline functions (because they shouldn't have any).
	if (it.second.is_definition) {
	continue;
	}

	DeclarationAvailability decl_availability;
	if (!it.second.calculateAvailability(&decl_availability)) {
	return false;
	abort();
	}

	if (!avail.merge(decl_availability)) {
	return false;
	}
	}
	*output = avail;
	return true;
	}

	bool Symbol::hasDeclaration(const CompilationType& type) const {
	for (const auto& decl_it : this->declarations) {
	for (const auto& compilation_it : decl_it.second.availability) {
	if (compilation_it.first == type) {
	return true;
	}
	}
	}
	return false;
	}

	void HeaderDatabase::parseAST(CompilationType type, ASTContext& ctx) {
	std::unique_lock<std::mutex> lock(this->mutex);
	Visitor visitor(*this, type, ctx);
	visitor.TraverseDecl(ctx.getTranslationUnitDecl());
	}

	std::string to_string(const AvailabilityValues& av) {
	std::stringstream ss;

	if (av.introduced != 0) {
	ss << "introduced = " << av.introduced << ", ";
	}

	if (av.deprecated != 0) {
	ss << "deprecated = " << av.deprecated << ", ";
	}

	if (av.obsoleted != 0) {
	ss << "obsoleted = " << av.obsoleted << ", ";
	}

	std::string result = ss.str();
	if (!result.empty()) {
	result = result.substr(0, result.length() - 2);
	}
	return result;
	}

	std::string to_string(const DeclarationType& type) {
	switch (type) {
	case DeclarationType::function:
	return "function";
	case DeclarationType::variable:
	return "variable";
	case DeclarationType::inconsistent:
	return "inconsistent";
	}
	abort();
	}

	std::string to_string(const DeclarationAvailability& decl_av) {
	std::stringstream ss;
	if (!decl_av.global_availability.empty()) {
	ss << to_string(decl_av.global_availability) << ", ";
	}

	for (const auto& it : decl_av.arch_availability) {
	if (!it.second.empty()) {
	ss << to_string(it.first) << ": " << to_string(it.second) << ", ";
	}
	}

	std::string result = ss.str();
	if (result.size() == 0) {
	return "no availability";
	}

	return result.substr(0, result.length() - 2);
	}

	std::string to_string(const Location& loc) {
	std::stringstream ss;
	ss << loc.filename << ":" << loc.start.line << ":" << loc.start.column;
	return ss.str();
	}