Fix ast print of variables with attributes

Previously clang AST prints the following declaration:

int fun_var_unused() {

  int x __attribute__((unused)) = 0;
  return x;
}

and

int __declspec(thread) x = 0;

as:

int fun_var_unused() {

  int x = 0 __attribute__((unused));
  return x;
}

and

int x = __declspec(thread) 0;

which is rejected by C/C++ parser. This patch modifies the logic to
print old C attributes for variables as:

int __attribute__((unused)) x = 0;
and the __declspec case as:

int __declspec(thread) x = 0;
Fixes: #59973

Previous version: D141714.

Differential Revision:https://reviews.llvm.org/D141714

Author: giulianobelinassi

clang/include/clang/Basic/Attr.td

@@ -300,10 +300,13 @@ class Spelling<string name, string variety, int version = 1> {
 }
 
 class GNU<string name> : Spelling<name, "GNU">;
-class Declspec<string name> : Spelling<name, "Declspec">;
+class Declspec<string name> : Spelling<name, "Declspec"> {
+  bit PrintOnLeft = 1;
+}
 class Microsoft<string name> : Spelling<name, "Microsoft">;
 class CXX11<string namespace, string name, int version = 1>
     : Spelling<name, "CXX11", version> {
+  bit CanPrintOnLeft = 0;
   string Namespace = namespace;
 }
 class C23<string namespace, string name, int version = 1>
@@ -559,6 +562,12 @@ class AttrSubjectMatcherAggregateRule<AttrSubject subject> {
 def SubjectMatcherForNamed : AttrSubjectMatcherAggregateRule<Named>;
 
 class Attr {
+  // Specifies that when printed, this attribute is meaningful on the
+  // 'left side' of the declaration.
+  bit CanPrintOnLeft = 1;
+  // Specifies that when printed, this attribute is required to be printed on
+  // the 'left side' of the declaration.
+  bit PrintOnLeft = 0;
   // The various ways in which an attribute can be spelled in source
   list<Spelling> Spellings;
   // The things to which an attribute can appertain
@@ -892,6 +901,7 @@ def AVRSignal : InheritableAttr, TargetSpecificAttr<TargetAVR> {
 }
 
 def AsmLabel : InheritableAttr {
+  let CanPrintOnLeft = 0;
   let Spellings = [CustomKeyword<"asm">, CustomKeyword<"__asm__">];
   let Args = [
     // Label specifies the mangled name for the decl.
@@ -1434,6 +1444,7 @@ def AllocSize : InheritableAttr {
 }
 
 def EnableIf : InheritableAttr {
+  let CanPrintOnLeft = 0;
   // Does not have a [[]] spelling because this attribute requires the ability
   // to parse function arguments but the attribute is not written in the type
   // position.
@@ -2920,6 +2931,7 @@ def Unavailable : InheritableAttr {
 }
 
 def DiagnoseIf : InheritableAttr {
+  let CanPrintOnLeft = 0;
   // Does not have a [[]] spelling because this attribute requires the ability
   // to parse function arguments but the attribute is not written in the type
   // position.

clang/include/clang/Basic/CMakeLists.txt

@@ -30,6 +30,16 @@ clang_tablegen(AttrList.inc -gen-clang-attr-list
   SOURCE Attr.td
   TARGET ClangAttrList)
 
+clang_tablegen(AttrLeftSideCanPrintList.inc -gen-clang-attr-can-print-left-list
+  -I ${CMAKE_CURRENT_SOURCE_DIR}/../../
+  SOURCE Attr.td
+  TARGET ClangAttrCanPrintLeftList)
+
+clang_tablegen(AttrLeftSideMustPrintList.inc -gen-clang-attr-must-print-left-list
+  -I ${CMAKE_CURRENT_SOURCE_DIR}/../../
+  SOURCE Attr.td
+  TARGET ClangAttrMustPrintLeftList)
+
 clang_tablegen(AttrSubMatchRulesList.inc -gen-clang-attr-subject-match-rule-list
   -I ${CMAKE_CURRENT_SOURCE_DIR}/../../
   SOURCE Attr.td

clang/lib/AST/DeclPrinter.cpp

@@ -49,6 +49,18 @@ namespace {
 
     void PrintObjCTypeParams(ObjCTypeParamList *Params);
 
+    enum class AttrPrintLoc {
+      None = 0,
+      Left = 1,
+      Right = 2,
+      Any = Left | Right,
+
+      LLVM_MARK_AS_BITMASK_ENUM(/*DefaultValue=*/Any)
+    };
+
+    void prettyPrintAttributes(Decl *D, raw_ostream &out,
+                               AttrPrintLoc loc = AttrPrintLoc::Any);
+
   public:
     DeclPrinter(raw_ostream &Out, const PrintingPolicy &Policy,
                 const ASTContext &Context, unsigned Indentation = 0,
@@ -117,7 +129,11 @@ namespace {
                                 const TemplateParameterList *Params);
     void printTemplateArguments(llvm::ArrayRef<TemplateArgumentLoc> Args,
                                 const TemplateParameterList *Params);
-    void prettyPrintAttributes(Decl *D);
+
+    inline void prettyPrintAttributes(Decl *D) {
+      prettyPrintAttributes(D, Out);
+    }
+
     void prettyPrintPragmas(Decl *D);
     void printDeclType(QualType T, StringRef DeclName, bool Pack = false);
   };
@@ -234,7 +250,40 @@ raw_ostream& DeclPrinter::Indent(unsigned Indentation) {
   return Out;
 }
 
-void DeclPrinter::prettyPrintAttributes(Decl *D) {
+static bool canPrintOnLeftSide(attr::Kind kind) {
+  switch (kind) {
+#include "clang/Basic/AttrLeftSideCanPrintList.inc"
+    return true;
+  default:
+    return false;
+  }
+}
+
+static bool canPrintOnLeftSide(const Attr *A) {
+  if (A->isStandardAttributeSyntax())
+    return false;
+
+  return canPrintOnLeftSide(A->getKind());
+}
+
+static bool mustPrintOnLeftSide(attr::Kind kind) {
+  switch (kind) {
+#include "clang/Basic/AttrLeftSideMustPrintList.inc"
+    return true;
+  default:
+    return false;
+  }
+}
+
+static bool mustPrintOnLeftSide(const Attr *A) {
+  if (A->isDeclspecAttribute())
+    return true;
+
+  return mustPrintOnLeftSide(A->getKind());
+}
+
+void DeclPrinter::prettyPrintAttributes(Decl *D, llvm::raw_ostream &Out,
+                                        AttrPrintLoc Loc) {
   if (Policy.PolishForDeclaration)
     return;
 
@@ -243,15 +292,32 @@ void DeclPrinter::prettyPrintAttributes(Decl *D) {
     for (auto *A : Attrs) {
       if (A->isInherited() || A->isImplicit())
         continue;
-      switch (A->getKind()) {
-#define ATTR(X)
-#define PRAGMA_SPELLING_ATTR(X) case attr::X:
-#include "clang/Basic/AttrList.inc"
-        break;
-      default:
-        A->printPretty(Out, Policy);
-        break;
+
+      AttrPrintLoc AttrLoc = AttrPrintLoc::Right;
+      if (mustPrintOnLeftSide(A)) {
+        // If we must always print on left side (e.g. declspec), then mark as
+        // so.
+        AttrLoc = AttrPrintLoc::Left;
+      } else if (canPrintOnLeftSide(A)) {
+        // For functions with body defined we print the attributes on the left
+        // side so that GCC accept our dumps as well.
+        if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D);
+            FD && FD->isThisDeclarationADefinition())
+          // In case Decl is a function with a body, then attrs should be print
+          // on the left side.
+          AttrLoc = AttrPrintLoc::Left;
+
+          // In case it is a variable declaration with a ctor, then allow
+          // printing on the left side for readbility.
+        else if (const VarDecl *VD = dyn_cast<VarDecl>(D);
+                   VD && VD->getInit() &&
+                   VD->getInitStyle() == VarDecl::CallInit)
+          AttrLoc = AttrPrintLoc::Left;
       }
+
+      // Only print the side matches the user requested.
+      if ((Loc & AttrLoc) != AttrPrintLoc::None)
+        A->printPretty(Out, Policy);
     }
   }
 }
@@ -613,6 +679,22 @@ void DeclPrinter::VisitFunctionDecl(FunctionDecl *D) {
       printTemplateParameters(D->getTemplateParameterList(I));
   }
 
+  std::string LeftsideAttrs;
+  llvm::raw_string_ostream LSAS(LeftsideAttrs);
+
+  prettyPrintAttributes(D, LSAS, AttrPrintLoc::Left);
+
+  // prettyPrintAttributes print a space on left side of the attribute.
+  if (LeftsideAttrs[0] == ' ') {
+    // Skip the space prettyPrintAttributes generated.
+    LeftsideAttrs.erase(0, LeftsideAttrs.find_first_not_of(' '));
+
+    // Add a single space between the attribute and the Decl name.
+    LSAS << ' ';
+  }
+
+  Out << LeftsideAttrs;
+
   CXXConstructorDecl *CDecl = dyn_cast<CXXConstructorDecl>(D);
   CXXConversionDecl *ConversionDecl = dyn_cast<CXXConversionDecl>(D);
   CXXDeductionGuideDecl *GuideDecl = dyn_cast<CXXDeductionGuideDecl>(D);
@@ -774,7 +856,7 @@ void DeclPrinter::VisitFunctionDecl(FunctionDecl *D) {
     Ty.print(Out, Policy, Proto);
   }
 
-  prettyPrintAttributes(D);
+  prettyPrintAttributes(D, Out, AttrPrintLoc::Right);
 
   if (D->isPure())
     Out << " = 0";
@@ -867,6 +949,23 @@ void DeclPrinter::VisitLabelDecl(LabelDecl *D) {
 void DeclPrinter::VisitVarDecl(VarDecl *D) {
   prettyPrintPragmas(D);
 
+  std::string LeftSide;
+  llvm::raw_string_ostream LeftSideStream(LeftSide);
+
+  // Print attributes that should be placed on the left, such as __declspec.
+  prettyPrintAttributes(D, LeftSideStream, AttrPrintLoc::Left);
+
+  // prettyPrintAttributes print a space on left side of the attribute.
+  if (LeftSide[0] == ' ') {
+    // Skip the space prettyPrintAttributes generated.
+    LeftSide.erase(0, LeftSide.find_first_not_of(' '));
+
+    // Add a single space between the attribute and the Decl name.
+    LeftSideStream << ' ';
+  }
+
+  Out << LeftSide;
+
   QualType T = D->getTypeSourceInfo()
     ? D->getTypeSourceInfo()->getType()
     : D->getASTContext().getUnqualifiedObjCPointerType(D->getType());
@@ -899,10 +998,19 @@ void DeclPrinter::VisitVarDecl(VarDecl *D) {
     }
   }
 
-  printDeclType(T, (isa<ParmVarDecl>(D) && Policy.CleanUglifiedParameters &&
-                    D->getIdentifier())
-                       ? D->getIdentifier()->deuglifiedName()
-                       : D->getName());
+  StringRef Name;
+
+  Name = (isa<ParmVarDecl>(D) && Policy.CleanUglifiedParameters &&
+          D->getIdentifier())
+             ? D->getIdentifier()->deuglifiedName()
+             : D->getName();
+
+  printDeclType(T, Name);
+
+  // Print the attributes that should be placed right before the end of the
+  // decl.
+  prettyPrintAttributes(D, Out, AttrPrintLoc::Right);
+
   Expr *Init = D->getInit();
   if (!Policy.SuppressInitializers && Init) {
     bool ImplicitInit = false;
@@ -931,7 +1039,6 @@ void DeclPrinter::VisitVarDecl(VarDecl *D) {
         Out << ")";
     }
   }
-  prettyPrintAttributes(D);
 }
 
 void DeclPrinter::VisitParmVarDecl(ParmVarDecl *D) {

clang/test/AST/ast-print-attr-knr.c

@@ -0,0 +1,17 @@
+// This file contain tests for attribute arguments on K&R functions.
+
+// RUN: %clang_cc1 -ast-print -x c -std=c89 -fms-extensions %s -o - | FileCheck %s
+
+// CHECK: int knr(i)
+// CHECK-NEXT: int i __attribute__((unused));
+// CHECK-NEXT: {
+// CHECK-NEXT: return 0;
+// CHECK-NEXT: }
+int knr(i) int i __attribute__((unused)); { return 0; }
+
+// CHECK: __attribute__((unused)) int knr2(i)
+// CHECK-NEXT: int i;
+// CHECK-NEXT: {
+// CHECK-NEXT: return 0;
+// CHECK-NEXT: }
+__attribute__((unused)) int knr2(i) int i; { return 0; }

clang/test/AST/ast-print-attr.c

@@ -32,3 +32,9 @@ int *fun_returns() __attribute__((ownership_returns(fun_returns)));
 
 // CHECK: void fun_holds(int *a) __attribute__((ownership_holds(fun_holds, 1)));
 void fun_holds(int *a) __attribute__((ownership_holds(fun_holds, 1)));
+
+// CHECK: int fun_var_unused() {
+// CHECK-NEXT: int x __attribute__((unused)) = 0;
+// CHECK-NEXT: return x;
+// CHECK-NEXT: }
+int fun_var_unused() { int x __attribute__((unused)) = 0; return x; }

clang/test/AST/ast-print-method-decl.cpp

@@ -95,7 +95,7 @@ struct DefMethodsWithoutBody {
   // CHECK-NEXT: DefMethodsWithoutBody() = default;
   ~DefMethodsWithoutBody() = default;
 
-  // CHECK-NEXT: void m1() __attribute__((alias("X")));
+  // CHECK-NEXT: __attribute__((alias("X"))) void m1();
   void m1() __attribute__((alias("X")));
 
   // CHECK-NEXT: };

clang/test/AST/ast-print-pragmas.cpp

@@ -93,7 +93,7 @@ void test_templates(int *List, int Length) {
 #ifdef MS_EXT
 #pragma init_seg(compiler)
 // MS-EXT: #pragma init_seg (.CRT$XCC){{$}}
-// MS-EXT-NEXT: int x = 3 __declspec(thread);
-int __declspec(thread) x = 3;
+// MS-EXT-NEXT: __declspec(thread) int x = 3;
+__declspec(thread) int x = 3;
 #endif //MS_EXT
 

clang/test/Analysis/blocks.mm

@@ -78,7 +78,7 @@ void testBlockWithCaptureByReference() {
 // CHECK-NEXT:   1: 5
 // WARNINGS-NEXT:   2: [B1.1] (CXXConstructExpr, StructWithCopyConstructor)
 // ANALYZER-NEXT:   2: [B1.1] (CXXConstructExpr, [B1.3], StructWithCopyConstructor)
-// CHECK-NEXT:   3: StructWithCopyConstructor s(5) __attribute__((blocks("byref")));
+// CHECK-NEXT:   3: __attribute__((blocks("byref"))) StructWithCopyConstructor s(5);
 // CHECK-NEXT:   4: ^{ }
 // CHECK-NEXT:   5: (void)([B1.4]) (CStyleCastExpr, ToVoid, void)
 // CHECK-NEXT:   Preds (1): B2

clang/test/OpenMP/assumes_codegen.cpp

@@ -67,41 +67,41 @@ int lambda_outer() {
 }
 #pragma omp end assumes
 
-// AST:      void foo() __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp"))) {
+// AST:      __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp"))) void foo() {
 // AST-NEXT: }
 // AST-NEXT: class BAR {
 // AST-NEXT: public:
-// AST-NEXT:     BAR() __attribute__((assume("ompx_range_bar_only"))) __attribute__((assume("ompx_range_bar_only_2"))) __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp")))     {
+// AST-NEXT:     __attribute__((assume("ompx_range_bar_only"))) __attribute__((assume("ompx_range_bar_only_2"))) __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp"))) BAR()      {
 // AST-NEXT:     }
-// AST-NEXT:     void bar1() __attribute__((assume("ompx_range_bar_only"))) __attribute__((assume("ompx_range_bar_only_2"))) __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp")))     {
+// AST-NEXT:     __attribute__((assume("ompx_range_bar_only"))) __attribute__((assume("ompx_range_bar_only_2"))) __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp"))) void bar1()     {
 // AST-NEXT:     }
-// AST-NEXT:     static void bar2() __attribute__((assume("ompx_range_bar_only"))) __attribute__((assume("ompx_range_bar_only_2"))) __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp")))     {
+// AST-NEXT:     __attribute__((assume("ompx_range_bar_only"))) __attribute__((assume("ompx_range_bar_only_2"))) __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp"))) static void bar2()      {
 // AST-NEXT:     }
 // AST-NEXT: };
-// AST-NEXT: void bar() __attribute__((assume("ompx_range_bar_only"))) __attribute__((assume("ompx_range_bar_only_2"))) __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp"))) {
+// AST-NEXT:  __attribute__((assume("ompx_range_bar_only"))) __attribute__((assume("ompx_range_bar_only_2"))) __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp"))) void bar() {
 // AST-NEXT:     BAR b;
 // AST-NEXT: }
 // AST-NEXT: void baz() __attribute__((assume("ompx_1234"))) __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp")));
 // AST-NEXT: template <typename T> class BAZ {
 // AST-NEXT: public:
-// AST-NEXT:     BAZ<T>() __attribute__((assume("ompx_1234"))) __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp")))     {
+// AST-NEXT:     __attribute__((assume("ompx_1234"))) __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp"))) BAZ<T>()      {
 // AST-NEXT:     }
-// AST-NEXT:     void baz1() __attribute__((assume("ompx_1234"))) __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp")))     {
+// AST-NEXT:     __attribute__((assume("ompx_1234"))) __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp")))  void baz1()     {
 // AST-NEXT:     }
-// AST-NEXT:     static void baz2() __attribute__((assume("ompx_1234"))) __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp")))     {
+// AST-NEXT:     __attribute__((assume("ompx_1234"))) __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp"))) static void baz2()      {
 // AST-NEXT:     }
 // AST-NEXT: };
 // AST-NEXT: template<> class BAZ<float> {
 // AST-NEXT: public:
-// AST-NEXT:     BAZ() __attribute__((assume("ompx_1234"))) __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp"))) __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp")))    {
+// AST-NEXT:     __attribute__((assume("ompx_1234"))) __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp"))) __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp")))  BAZ()    {
 // AST-NEXT:     }
 // AST-NEXT:     void baz1() __attribute__((assume("ompx_1234"))) __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp"))) __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp")));
 // AST-NEXT:     static void baz2() __attribute__((assume("ompx_1234"))) __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp"))) __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp")));
 // AST-NEXT: };
-// AST-NEXT: void baz() __attribute__((assume("ompx_1234"))) __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp"))) {
+// AST-NEXT: __attribute__((assume("ompx_1234"))) __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp"))) void baz() {
 // AST-NEXT:     BAZ<float> b;
 // AST-NEXT: }
-// AST-NEXT: int lambda_outer() __attribute__((assume("ompx_lambda_assumption"))) __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp"))) {
+// AST-NEXT: __attribute__((assume("ompx_lambda_assumption"))) __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp"))) int lambda_outer() {
 // AST-NEXT:     auto lambda_inner = []() {
 // AST-NEXT:         return 42;
 // AST-NEXT:     };

clang/test/OpenMP/assumes_print.cpp

@@ -37,8 +37,8 @@ void baz() {
 }
 #pragma omp end assumes
 
-// CHECK: void foo() __attribute__((assume("omp_no_openmp_routines"))) __attribute__((assume("omp_no_openmp")))
-// CHECK: void bar() __attribute__((assume("ompx_range_bar_only"))) __attribute__((assume("ompx_range_bar_only_2"))) __attribute__((assume("omp_no_openmp_routines"))) __attribute__((assume("omp_no_openmp")))
-// CHECK: void baz() __attribute__((assume("ompx_1234"))) __attribute__((assume("omp_no_openmp_routines"))) __attribute__((assume("omp_no_openmp")))
+// CHECK: __attribute__((assume("omp_no_openmp_routines"))) __attribute__((assume("omp_no_openmp"))) void foo()
+// CHECK: __attribute__((assume("ompx_range_bar_only"))) __attribute__((assume("ompx_range_bar_only_2"))) __attribute__((assume("omp_no_openmp_routines"))) __attribute__((assume("omp_no_openmp"))) void bar()
+// CHECK: __attribute__((assume("ompx_1234"))) __attribute__((assume("omp_no_openmp_routines"))) __attribute__((assume("omp_no_openmp"))) void baz()
 
 #endif