[Clang] Fix the do while statement disappearing in AST when an error occurs in the conditional expression of the for statement

Author: yronglin

clang/lib/Parse/ParseStmt.cpp

@@ -2158,8 +2158,10 @@ StmtResult Parser::ParseForStatement(SourceLocation *TrailingElseLoc) {
         // for-range-declaration next.
         bool MightBeForRangeStmt = !ForRangeInfo.ParsedForRangeDecl();
         ColonProtectionRAIIObject ColonProtection(*this, MightBeForRangeStmt);
+        SourceLocation SecondPartStart = Tok.getLocation();
+        Sema::ConditionKind CK = Sema::ConditionKind::Boolean;
         SecondPart = ParseCXXCondition(
-            nullptr, ForLoc, Sema::ConditionKind::Boolean,
+            nullptr, ForLoc, CK,
             // FIXME: recovery if we don't see another semi!
             /*MissingOK=*/true, MightBeForRangeStmt ? &ForRangeInfo : nullptr,
             /*EnterForConditionScope*/ true);
@@ -2178,6 +2180,19 @@ StmtResult Parser::ParseForStatement(SourceLocation *TrailingElseLoc) {
                 << FixItHint::CreateRemoval(EmptyInitStmtSemiLoc);
           }
         }
+
+        if (SecondPart.isInvalid()) {
+          ExprResult CondExpr = Actions.CreateRecoveryExpr(
+              SecondPartStart,
+              Tok.getLocation() == SecondPartStart ? SecondPartStart
+                                                   : PrevTokLocation,
+              {}, Actions.PreferredConditionType(CK));
+          if (!CondExpr.isInvalid())
+            SecondPart = Actions.ActOnCondition(getCurScope(), ForLoc,
+                                                CondExpr.get(), CK,
+                                                /*MissingOK=*/false);
+        }
+
       } else {
         // We permit 'continue' and 'break' in the condition of a for loop.
         getCurScope()->AddFlags(Scope::BreakScope | Scope::ContinueScope);

clang/test/AST/ast-dump-recovery.cpp

@@ -432,3 +432,18 @@ void RecoveryToDoWhileStmtCond() {
   // CHECK-NEXT:      `-IntegerLiteral {{.*}} 'int' 10
   do {} while (some_invalid_val + 1 < 10);
 }
+
+void RecoveryForStmtCond() {
+  // CHECK:FunctionDecl {{.*}} RecoveryForStmtCond
+  // CHECK-NEXT:`-CompoundStmt {{.*}}
+  // CHECK-NEXT:  `-ForStmt {{.*}}
+  // CHECK-NEXT:    |-DeclStmt {{.*}}
+  // CHECK-NEXT:    | `-VarDecl {{.*}}
+  // CHECK-NEXT:    |   `-IntegerLiteral {{.*}} <col:16> 'int' 0
+  // CHECK-NEXT:    |-<<<NULL>>>
+  // CHECK-NEXT:    |-RecoveryExpr {{.*}} 'bool' contains-errors
+  // CHECK-NEXT:    |-UnaryOperator {{.*}} 'int' lvalue prefix '++'
+  // CHECK-NEXT:    | `-DeclRefExpr {{.*}} 'int' lvalue Var {{.*}} 'i' 'int'
+  // CHECK-NEXT:    `-CompoundStmt {{.*}}
+  for (int i = 0; i < invalid; ++i) {}
+}

clang/test/SemaCXX/constexpr-function-recovery-crash.cpp

@@ -106,3 +106,4 @@ TEST_EVALUATE(ForCond, for (; !!;){};);// expected-error + {{}}
 TEST_EVALUATE(ForInc, for (;; !!){};);// expected-error + {{}}
                                       // expected-note@-1 + {{infinite loop}}
                                       // expected-note@-2 {{in call}}
+TEST_EVALUATE(ForCondUnDef, for (;some_cond;){};);        // expected-error + {{}}