[clang-tidy] Add modernize-use-std-format check (#90397)

Add a new clang-tidy check that converts absl::StrFormat (and similar
functions) to std::format (and similar functions.)

Split the configuration of FormatStringConverter out to a separate
Configuration class so that we don't risk confusion by passing two
boolean configuration parameters into the constructor. Add
AllowTrailingNewlineRemoval option since we never want to remove
trailing newlines in this check.

1 files changed, 107 insertions, 0 deletions

diff --git a/clang-tools-extra/clang-tidy/modernize/UseStdFormatCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseStdFormatCheck.cpp
new file mode 100644
index 0000000..6cef21f
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/modernize/UseStdFormatCheck.cpp
@@ -0,0 +1,107 @@
+//===--- UseStdFormatCheck.cpp - clang-tidy -------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "UseStdFormatCheck.h"
+#include "../utils/FormatStringConverter.h"
+#include "../utils/Matchers.h"
+#include "../utils/OptionsUtils.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Lex/Lexer.h"
+#include "clang/Tooling/FixIt.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::modernize {
+
+namespace {
+AST_MATCHER(StringLiteral, isOrdinary) { return Node.isOrdinary(); }
+} // namespace
+
+UseStdFormatCheck::UseStdFormatCheck(StringRef Name, ClangTidyContext *Context)
+    : ClangTidyCheck(Name, Context),
+      StrictMode(Options.getLocalOrGlobal("StrictMode", false)),
+      StrFormatLikeFunctions(utils::options::parseStringList(
+          Options.get("StrFormatLikeFunctions", ""))),
+      ReplacementFormatFunction(
+          Options.get("ReplacementFormatFunction", "std::format")),
+      IncludeInserter(Options.getLocalOrGlobal("IncludeStyle",
+                                               utils::IncludeSorter::IS_LLVM),
+                      areDiagsSelfContained()),
+      MaybeHeaderToInclude(Options.get("FormatHeader")) {
+  if (StrFormatLikeFunctions.empty())
+    StrFormatLikeFunctions.push_back("absl::StrFormat");
+
+  if (!MaybeHeaderToInclude && ReplacementFormatFunction == "std::format")
+    MaybeHeaderToInclude = "<format>";
+}
+
+void UseStdFormatCheck::registerPPCallbacks(const SourceManager &SM,
+                                            Preprocessor *PP,
+                                            Preprocessor *ModuleExpanderPP) {
+  IncludeInserter.registerPreprocessor(PP);
+}
+
+void UseStdFormatCheck::registerMatchers(MatchFinder *Finder) {
+  Finder->addMatcher(
+      callExpr(argumentCountAtLeast(1),
+               hasArgument(0, stringLiteral(isOrdinary())),
+               callee(functionDecl(unless(cxxMethodDecl()),
+                                   matchers::matchesAnyListedName(
+                                       StrFormatLikeFunctions))
+                          .bind("func_decl")))
+          .bind("strformat"),
+      this);
+}
+
+void UseStdFormatCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
+  using utils::options::serializeStringList;
+  Options.store(Opts, "StrictMode", StrictMode);
+  Options.store(Opts, "StrFormatLikeFunctions",
+                serializeStringList(StrFormatLikeFunctions));
+  Options.store(Opts, "ReplacementFormatFunction", ReplacementFormatFunction);
+  Options.store(Opts, "IncludeStyle", IncludeInserter.getStyle());
+  if (MaybeHeaderToInclude)
+    Options.store(Opts, "FormatHeader", *MaybeHeaderToInclude);
+}
+
+void UseStdFormatCheck::check(const MatchFinder::MatchResult &Result) {
+  const unsigned FormatArgOffset = 0;
+  const auto *OldFunction = Result.Nodes.getNodeAs<FunctionDecl>("func_decl");
+  const auto *StrFormat = Result.Nodes.getNodeAs<CallExpr>("strformat");
+
+  utils::FormatStringConverter::Configuration ConverterConfig;
+  ConverterConfig.StrictMode = StrictMode;
+  utils::FormatStringConverter Converter(Result.Context, StrFormat,
+                                         FormatArgOffset, ConverterConfig,
+                                         getLangOpts());
+  const Expr *StrFormatCall = StrFormat->getCallee();
+  if (!Converter.canApply()) {
+    diag(StrFormat->getBeginLoc(),
+         "unable to use '%0' instead of %1 because %2")
+        << StrFormatCall->getSourceRange() << ReplacementFormatFunction
+        << OldFunction->getIdentifier()
+        << Converter.conversionNotPossibleReason();
+    return;
+  }
+
+  DiagnosticBuilder Diag =
+      diag(StrFormatCall->getBeginLoc(), "use '%0' instead of %1")
+      << ReplacementFormatFunction << OldFunction->getIdentifier();
+  Diag << FixItHint::CreateReplacement(
+      CharSourceRange::getTokenRange(StrFormatCall->getSourceRange()),
+      ReplacementFormatFunction);
+  Converter.applyFixes(Diag, *Result.SourceManager);
+
+  if (MaybeHeaderToInclude)
+    Diag << IncludeInserter.createIncludeInsertion(
+        Result.Context->getSourceManager().getFileID(
+            StrFormatCall->getBeginLoc()),
+        *MaybeHeaderToInclude);
+}
+
+} // namespace clang::tidy::modernize