Clean up remaining executable_semantics clang-tidy warnings (#906)

Co-authored-by: Geoff Romer <gromer@google.com>

executable_semantics/ast/declaration.h

@@ -6,6 +6,7 @@
 #define EXECUTABLE_SEMANTICS_AST_DECLARATION_H_
 
 #include <string>
+#include <utility>
 #include <vector>
 
 #include "common/ostream.h"
@@ -38,7 +39,7 @@ class Declaration {
   };
 
   Declaration(const Member&) = delete;
-  Declaration& operator=(const Member&) = delete;
+  auto operator=(const Member&) -> Declaration& = delete;
 
   void Print(llvm::raw_ostream& out) const;
   LLVM_DUMP_METHOD void Dump() const { Print(llvm::errs()); }
@@ -152,7 +153,7 @@ class ChoiceDeclaration : public Declaration {
   class Alternative {
    public:
     Alternative(std::string name, Nonnull<Expression*> signature)
-        : name_(name), signature_(signature) {}
+        : name_(std::move(name)), signature_(signature) {}
 
     auto name() const -> const std::string& { return name_; }
     auto signature() const -> const Expression& { return *signature_; }

executable_semantics/ast/member.h

@@ -28,7 +28,7 @@ class Member {
   enum class Kind { FieldMember };
 
   Member(const Member&) = delete;
-  Member& operator=(const Member&) = delete;
+  auto operator=(const Member&) -> Member& = delete;
 
   void Print(llvm::raw_ostream& out) const;
   LLVM_DUMP_METHOD void Dump() const { Print(llvm::errs()); }

executable_semantics/ast/pattern.h

@@ -37,7 +37,7 @@ class Pattern {
   };
 
   Pattern(const Pattern&) = delete;
-  Pattern& operator=(const Pattern&) = delete;
+  auto operator=(const Pattern&) -> Pattern& = delete;
 
   void Print(llvm::raw_ostream& out) const;
   LLVM_DUMP_METHOD void Dump() const { Print(llvm::errs()); }
@@ -206,7 +206,7 @@ class AlternativePattern : public Pattern {
 // expression.
 class ExpressionPattern : public Pattern {
  public:
-  ExpressionPattern(Nonnull<Expression*> expression)
+  explicit ExpressionPattern(Nonnull<Expression*> expression)
       : Pattern(Kind::ExpressionPattern, expression->source_loc()),
         expression_(expression) {}
 

executable_semantics/ast/source_location.h

@@ -26,7 +26,7 @@ class SourceLocation {
   auto operator=(const SourceLocation&) -> SourceLocation& = default;
   auto operator=(SourceLocation&&) -> SourceLocation& = default;
 
-  bool operator==(SourceLocation other) const {
+  auto operator==(SourceLocation other) const -> bool {
     return filename_ == other.filename_ && line_num_ == other.line_num_;
   }
 

executable_semantics/interpreter/interpreter.cpp

@@ -24,7 +24,6 @@
 #include "llvm/Support/Casting.h"
 
 using llvm::cast;
-using llvm::dyn_cast;
 
 namespace Carbon {
 

executable_semantics/interpreter/type_checker.cpp

@@ -1191,7 +1191,7 @@ void TypeChecker::TypeCheck(Nonnull<Declaration*> d, const TypeEnv& types,
 void TypeChecker::TopLevel(Nonnull<Declaration*> d, TypeCheckContext* tops) {
   switch (d->kind()) {
     case Declaration::Kind::FunctionDeclaration: {
-      FunctionDeclaration& func_def = cast<FunctionDeclaration>(*d);
+      auto& func_def = cast<FunctionDeclaration>(*d);
       auto t = TypeOfFunDef(tops->types, tops->values, &func_def);
       tops->types.Set(func_def.name(), t);
       interpreter_.InitEnv(*d, &tops->values);
@@ -1199,8 +1199,7 @@ void TypeChecker::TopLevel(Nonnull<Declaration*> d, TypeCheckContext* tops) {
     }
 
     case Declaration::Kind::ClassDeclaration: {
-      const ClassDefinition& class_def =
-          cast<ClassDeclaration>(*d).definition();
+      const auto& class_def = cast<ClassDeclaration>(*d).definition();
       auto st = TypeOfClassDef(&class_def, tops->types, tops->values);
       Address a = interpreter_.AllocateValue(st);
       tops->values.Set(class_def.name(), a);  // Is this obsolete?

executable_semantics/interpreter/type_checker.h

@@ -71,7 +71,7 @@ class TypeChecker {
   };
 
   struct TCResult {
-    TCResult(TypeEnv types) : types(types) {}
+    explicit TCResult(TypeEnv types) : types(types) {}
 
     TypeEnv types;
   };

executable_semantics/main.cpp

@@ -11,12 +11,12 @@
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/InitLLVM.h"
 
-int main(int argc, char* argv[]) {
+auto main(int argc, char* argv[]) -> int {
   llvm::setBugReportMsg(
       "Please report issues to "
       "https://github.com/carbon-language/carbon-lang/issues and include the "
       "crash backtrace.\n");
-  llvm::InitLLVM(argc, argv);
+  llvm::InitLLVM init_llvm(argc, argv);
 
   // Printing to stderr should flush stdout. This is most noticeable when stderr
   // is piped to stdout.

executable_semantics/syntax/bison_wrap.h

@@ -24,6 +24,7 @@ class BisonWrap {
   }
 
   // Support transparent conversion to the wrapped type.
+  // NOLINTNEXTLINE(google-explicit-constructor)
   operator T() { return Release(); }
 
   // Deliberately releases the contained value. Errors if not initialized.

executable_semantics/syntax/parse_and_lex_context.h

@@ -44,10 +44,10 @@ class ParseAndLexContext {
 }  // namespace Carbon
 
 // Gives flex the yylex prototype we want.
-#define YY_DECL                                                            \
-  Carbon::Parser::symbol_type yylex(Carbon::Nonnull<Carbon::Arena*> arena, \
-                                    yyscan_t yyscanner,                    \
-                                    Carbon::ParseAndLexContext& context)
+#define YY_DECL                                                         \
+  auto yylex(Carbon::Nonnull<Carbon::Arena*> arena, yyscan_t yyscanner, \
+             Carbon::ParseAndLexContext& context)                       \
+      -> Carbon::Parser::symbol_type
 
 // Declares yylex for the parser's sake.
 YY_DECL;