1 files changed, 194 insertions, 2 deletions
diff --git a/clang-tools-extra/clang-tidy/utils/FixItHintUtils.cpp b/clang-tools-extra/clang-tidy/utils/FixItHintUtils.cpp
index c30a59e99ba..a9c95e9f381 100644
--- a/clang-tools-extra/clang-tidy/utils/FixItHintUtils.cpp
+++ b/clang-tools-extra/clang-tidy/utils/FixItHintUtils.cpp
@@ -9,6 +9,7 @@
 #include "FixItHintUtils.h"
 #include "LexerUtils.h"
 #include "clang/AST/ASTContext.h"
+#include "clang/AST/Type.h"
 
 namespace clang {
 namespace tidy {
@@ -26,10 +27,201 @@ FixItHint changeVarDeclToReference(const VarDecl &Var, ASTContext &Context) {
   return FixItHint::CreateInsertion(AmpLocation, "&");
 }
 
-FixItHint changeVarDeclToConst(const VarDecl &Var) {
-  return FixItHint::CreateInsertion(Var.getTypeSpecStartLoc(), "const ");
+static bool isValueType(const Type *T) {
+  return !(isa<PointerType>(T) || isa<ReferenceType>(T) || isa<ArrayType>(T) ||
+           isa<MemberPointerType>(T) || isa<ObjCObjectPointerType>(T));
 }
+static bool isValueType(QualType QT) { return isValueType(QT.getTypePtr()); }
+static bool isMemberOrFunctionPointer(QualType QT) {
+  return (QT->isPointerType() && QT->isFunctionPointerType()) ||
+         isa<MemberPointerType>(QT.getTypePtr());
+}
+
+static bool locDangerous(SourceLocation S) {
+  return S.isInvalid() || S.isMacroID();
+}
+
+static Optional<SourceLocation>
+skipLParensBackwards(SourceLocation Start, const ASTContext &Context) {
+  if (locDangerous(Start))
+    return None;
+
+  auto PreviousTokenLParen = [&Start, &Context]() {
+    Token T;
+    T = lexer::getPreviousToken(Start, Context.getSourceManager(),
+                                Context.getLangOpts());
+    return T.is(tok::l_paren);
+  };
+
+  while (Start.isValid() && PreviousTokenLParen())
+    Start = lexer::findPreviousTokenStart(Start, Context.getSourceManager(),
+                                          Context.getLangOpts());
+
+  if (locDangerous(Start))
+    return None;
+  return Start;
+}
+
+static Optional<FixItHint> fixIfNotDangerous(SourceLocation Loc,
+                                             StringRef Text) {
+  if (locDangerous(Loc))
+    return None;
+  return FixItHint::CreateInsertion(Loc, Text);
+}
+
+// Build a string that can be emitted as FixIt with either a space in before
+// or after the qualifier, either ' const' or 'const '.
+static std::string buildQualifier(DeclSpec::TQ Qualifier,
+                                  bool WhitespaceBefore = false) {
+  if (WhitespaceBefore)
+    return (llvm::Twine(' ') + DeclSpec::getSpecifierName(Qualifier)).str();
+  return (llvm::Twine(DeclSpec::getSpecifierName(Qualifier)) + " ").str();
+}
+
+static Optional<FixItHint> changeValue(const VarDecl &Var,
+                                       DeclSpec::TQ Qualifier,
+                                       QualifierTarget QualTarget,
+                                       QualifierPolicy QualPolicy,
+                                       const ASTContext &Context) {
+  switch (QualPolicy) {
+  case QualifierPolicy::Left:
+    return fixIfNotDangerous(Var.getTypeSpecStartLoc(),
+                             buildQualifier(Qualifier));
+  case QualifierPolicy::Right:
+    Optional<SourceLocation> IgnoredParens =
+        skipLParensBackwards(Var.getLocation(), Context);
+
+    if (IgnoredParens)
+      return fixIfNotDangerous(*IgnoredParens, buildQualifier(Qualifier));
+    return None;
+  }
+}
+
+static Optional<FixItHint> changePointerItself(const VarDecl &Var,
+                                               DeclSpec::TQ Qualifier,
+                                               const ASTContext &Context) {
+  if (locDangerous(Var.getLocation()))
+    return None;
+
+  Optional<SourceLocation> IgnoredParens =
+      skipLParensBackwards(Var.getLocation(), Context);
+  if (IgnoredParens)
+    return fixIfNotDangerous(*IgnoredParens, buildQualifier(Qualifier));
+  return None;
+}
+
+static Optional<FixItHint>
+changePointer(const VarDecl &Var, DeclSpec::TQ Qualifier, const Type *Pointee,
+              QualifierTarget QualTarget, QualifierPolicy QualPolicy,
+              const ASTContext &Context) {
+  // The pointer itself shall be marked as `const`. This is always to the right
+  // of the '*' or in front of the identifier.
+  if (QualTarget == QualifierTarget::Value)
+    return changePointerItself(Var, Qualifier, Context);
+
+  // Mark the pointee `const` that is a normal value (`int* p = nullptr;`).
+  if (QualTarget == QualifierTarget::Pointee && isValueType(Pointee)) {
+    // Adding the `const` on the left side is just the beginning of the type
+    // specification. (`const int* p = nullptr;`)
+    if (QualPolicy == QualifierPolicy::Left)
+      return fixIfNotDangerous(Var.getTypeSpecStartLoc(),
+                               buildQualifier(Qualifier));
 
+    // Adding the `const` on the right side of the value type requires finding
+    // the `*` token and placing the `const` left of it.
+    // (`int const* p = nullptr;`)
+    if (QualPolicy == QualifierPolicy::Right) {
+      SourceLocation BeforeStar = lexer::findPreviousTokenKind(
+          Var.getLocation(), Context.getSourceManager(), Context.getLangOpts(),
+          tok::star);
+      if (locDangerous(BeforeStar))
+        return None;
+
+      Optional<SourceLocation> IgnoredParens =
+          skipLParensBackwards(BeforeStar, Context);
+
+      if (IgnoredParens)
+        return fixIfNotDangerous(*IgnoredParens,
+                                 buildQualifier(Qualifier, true));
+      return None;
+    }
+  }
+
+  if (QualTarget == QualifierTarget::Pointee && Pointee->isPointerType()) {
+    // Adding the `const` to the pointee if the pointee is a pointer
+    // is the same as 'QualPolicy == Right && isValueType(Pointee)'.
+    // The `const` must be left of the last `*` token.
+    // (`int * const* p = nullptr;`)
+    SourceLocation BeforeStar = lexer::findPreviousTokenKind(
+        Var.getLocation(), Context.getSourceManager(), Context.getLangOpts(),
+        tok::star);
+    return fixIfNotDangerous(BeforeStar, buildQualifier(Qualifier, true));
+  }
+
+  return None;
+}
+
+static Optional<FixItHint>
+changeReferencee(const VarDecl &Var, DeclSpec::TQ Qualifier, QualType Pointee,
+                 QualifierTarget QualTarget, QualifierPolicy QualPolicy,
+                 const ASTContext &Context) {
+  if (QualPolicy == QualifierPolicy::Left && isValueType(Pointee))
+    return fixIfNotDangerous(Var.getTypeSpecStartLoc(),
+                             buildQualifier(Qualifier));
+
+  SourceLocation BeforeRef = lexer::findPreviousAnyTokenKind(
+      Var.getLocation(), Context.getSourceManager(), Context.getLangOpts(),
+      tok::amp, tok::ampamp);
+  Optional<SourceLocation> IgnoredParens =
+      skipLParensBackwards(BeforeRef, Context);
+  if (IgnoredParens)
+    return fixIfNotDangerous(*IgnoredParens, buildQualifier(Qualifier, true));
+
+  return None;
+}
+
+Optional<FixItHint> addQualifierToVarDecl(const VarDecl &Var,
+                                          const ASTContext &Context,
+                                          DeclSpec::TQ Qualifier,
+                                          QualifierTarget QualTarget,
+                                          QualifierPolicy QualPolicy) {
+  assert((QualPolicy == QualifierPolicy::Left ||
+          QualPolicy == QualifierPolicy::Right) &&
+         "Unexpected Insertion Policy");
+  assert((QualTarget == QualifierTarget::Pointee ||
+          QualTarget == QualifierTarget::Value) &&
+         "Unexpected Target");
+
+  QualType ParenStrippedType = Var.getType().IgnoreParens();
+  if (isValueType(ParenStrippedType))
+    return changeValue(Var, Qualifier, QualTarget, QualPolicy, Context);
+
+  if (ParenStrippedType->isReferenceType())
+    return changeReferencee(Var, Qualifier, Var.getType()->getPointeeType(),
+                            QualTarget, QualPolicy, Context);
+
+  if (isMemberOrFunctionPointer(ParenStrippedType))
+    return changePointerItself(Var, Qualifier, Context);
+
+  if (ParenStrippedType->isPointerType())
+    return changePointer(Var, Qualifier,
+                         ParenStrippedType->getPointeeType().getTypePtr(),
+                         QualTarget, QualPolicy, Context);
+
+  if (ParenStrippedType->isArrayType()) {
+    const Type *AT = ParenStrippedType->getBaseElementTypeUnsafe();
+    assert(AT && "Did not retrieve array element type for an array.");
+
+    if (isValueType(AT))
+      return changeValue(Var, Qualifier, QualTarget, QualPolicy, Context);
+
+    if (AT->isPointerType())
+      return changePointer(Var, Qualifier, AT->getPointeeType().getTypePtr(),
+                           QualTarget, QualPolicy, Context);
+  }
+
+  return None;
+}
 } // namespace fixit
 } // namespace utils
 } // namespace tidy