Commit 2d6829bb authored by Matheus Izvekov's avatar Matheus Izvekov
Browse files

[clang] disable implicit moves when not in CPlusPLus 



See PR51842.

This fixes an assert firing in the static analyzer, triggered by implicit moves
in blocks in C mode:

This also simplifies the AST a little bit when compiling non C++ code,
as the xvalue implicit casts are not inserted.

We keep and test that the nrvo flag is still being set on the VarDecls,
as that is still a bit beneficial while not really making anything
more complicated.

Signed-off-by: default avatarMatheus Izvekov <mizvekov@gmail.com>

Reviewed By: NoQ

Differential Revision: https://reviews.llvm.org/D109654
parent f2874054

clang/lib/Sema/SemaStmt.cpp

+2 −1
Original line number Diff line number Diff line
@@ -3481,7 +3481,8 @@ VerifyInitializationSequenceCXX98(const Sema &S, 
ExprResult Sema::PerformMoveOrCopyInitialization(

    const InitializedEntity &Entity, const NamedReturnInfo &NRInfo, Expr *Value,

    bool SupressSimplerImplicitMoves) {

  if ((!getLangOpts().CPlusPlus2b || SupressSimplerImplicitMoves) &&

  if (getLangOpts().CPlusPlus &&

      (!getLangOpts().CPlusPlus2b || SupressSimplerImplicitMoves) &&

      NRInfo.isMoveEligible()) {

    ImplicitCastExpr AsRvalue(ImplicitCastExpr::OnStack, Value->getType(),

                              CK_NoOp, Value, VK_XValue, FPOptionsOverride());

clang/test/AST/nrvo.c

0 → 100644
+29 −0
Original line number Diff line number Diff line 
// RUN: %clang_cc1 -ast-dump -fblocks %s | FileCheck -strict-whitespace %s



struct A {};



struct A f1() {

  // CHECK:      FunctionDecl 0x{{[^ ]*}} <line:[[@LINE-1]]:1, line:{{[^:]*}}:1> line:[[@LINE-1]]:10 f1 'struct A ()'

  // CHECK-NEXT: CompoundStmt 0x{{[^ ]*}} <col:15, line:{{[^:]*}}:1>

  struct A a;

  // CHECK-NEXT: DeclStmt 0x{{[^ ]*}} <line:[[@LINE-1]]:3, col:13>

  // CHECK-NEXT: VarDecl 0x{{[^ ]*}} <col:3, col:12> col:12 used a 'struct A':'struct A' nrvo

  return a;

  // CHECK-NEXT: ReturnStmt 0x{{[^ ]*}} <line:[[@LINE-1]]:3, col:10>

  // CHECK-NEXT: ImplicitCastExpr 0x{{[^ ]*}} <col:10> 'struct A':'struct A' <LValueToRValue>

  // CHECK-NEXT: DeclRefExpr 0x{{[^ ]*}} <col:10> 'struct A':'struct A' lvalue Var 0x{{[^ ]*}} 'a' 'struct A':'struct A'

}



void f2() {

  (void)^{

    // CHECK:      BlockDecl 0x{{[^ ]*}} <line:[[@LINE-1]]:9, line:{{[^:]*}}:3> line:[[@LINE-1]]:9

    // CHECK-NEXT: CompoundStmt 0x{{[^ ]*}} <col:10, line:{{[^:]*}}:3>

    struct A a;

    // CHECK-NEXT: DeclStmt 0x{{[^ ]*}} <line:[[@LINE-1]]:5, col:15>

    // CHECK-NEXT: VarDecl 0x{{[^ ]*}} <col:5, col:14> col:14 used a 'struct A':'struct A' nrvo

    return a;

    // CHECK-NEXT: ReturnStmt 0x{{[^ ]*}} <line:[[@LINE-1]]:5, col:12>

    // CHECK-NEXT: ImplicitCastExpr 0x{{[^ ]*}} <col:12> 'struct A':'struct A' <LValueToRValue>

    // CHECK-NEXT: DeclRefExpr 0x{{[^ ]*}} <col:12> 'struct A':'struct A' lvalue Var 0x{{[^ ]*}} 'a' 'struct A':'struct A'

  }();

}

clang/test/Analysis/blocks-nrvo.c

0 → 100644
+14 −0
Original line number Diff line number Diff line 
// RUN: %clang_analyze_cc1 -w -analyzer-checker=core -fblocks -verify %s



// expected-no-diagnostics



typedef struct {

  int x;

} S;



void foo() {

  ^{

    S s;

    return s; // no-crash

  };

}