[clang] [Clang] Fix the for statement disappearing in AST when an error occurs in the conditional expression of the for statement (PR #65381)

[via cfe-commits]

https://github.com/yronglin updated https://github.com/llvm/llvm-project/pull/65381:

>From 1eb3e96d9cfc843139e6198b59bed56bac288a3c Mon Sep 17 00:00:00 2001
From: yronglin <yronglin777 at gmail.com>
Date: Wed, 6 Sep 2023 00:00:18 +0800
Subject: [PATCH 1/2] [Clang] Fix the do while statement disappearing in AST
 when an error occurs in the conditional expression of the for statement

---
 clang/lib/Parse/ParseStmt.cpp                   | 17 ++++++++++++++++-
 clang/test/AST/ast-dump-recovery.cpp            | 15 +++++++++++++++
 .../constexpr-function-recovery-crash.cpp       |  1 +
 3 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/clang/lib/Parse/ParseStmt.cpp b/clang/lib/Parse/ParseStmt.cpp
index 110806ef0c77d63..9c6327b56591194 100644
--- a/clang/lib/Parse/ParseStmt.cpp
+++ b/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);
diff --git a/clang/test/AST/ast-dump-recovery.cpp b/clang/test/AST/ast-dump-recovery.cpp
index c882b4659a7310e..278b9fc000b5740 100644
--- a/clang/test/AST/ast-dump-recovery.cpp
+++ b/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) {}
+}
diff --git a/clang/test/SemaCXX/constexpr-function-recovery-crash.cpp b/clang/test/SemaCXX/constexpr-function-recovery-crash.cpp
index e1d97ceafbe9d15..90ee7892b2fc2e7 100644
--- a/clang/test/SemaCXX/constexpr-function-recovery-crash.cpp
+++ b/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 at -1 + {{infinite loop}}
                                       // expected-note at -2 {{in call}}
+TEST_EVALUATE(ForCondUnDef, for (;some_cond;){};);        // expected-error + {{}}

>From 712eb699caf7ecf958bcc2a9ee81b9fca967c4d7 Mon Sep 17 00:00:00 2001
From: yronglin <yronglin777 at gmail.com>
Date: Thu, 7 Sep 2023 19:26:19 +0800
Subject: [PATCH 2/2] Address comments

Co-authored-by: Shafik Yaghmour <shafik at users.noreply.github.com>
---
 clang/lib/Parse/ParseStmt.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/clang/lib/Parse/ParseStmt.cpp b/clang/lib/Parse/ParseStmt.cpp
index 9c6327b56591194..fb883c08a745cfa 100644
--- a/clang/lib/Parse/ParseStmt.cpp
+++ b/clang/lib/Parse/ParseStmt.cpp
@@ -2161,10 +2161,10 @@ StmtResult Parser::ParseForStatement(SourceLocation *TrailingElseLoc) {
         SourceLocation SecondPartStart = Tok.getLocation();
         Sema::ConditionKind CK = Sema::ConditionKind::Boolean;
         SecondPart = ParseCXXCondition(
-            nullptr, ForLoc, CK,
+            /*InitStmt=*/nullptr, ForLoc, CK,
             // FIXME: recovery if we don't see another semi!
             /*MissingOK=*/true, MightBeForRangeStmt ? &ForRangeInfo : nullptr,
-            /*EnterForConditionScope*/ true);
+            /*EnterForConditionScope=*/true);
 
         if (ForRangeInfo.ParsedForRangeDecl()) {
           Diag(FirstPart.get() ? FirstPart.get()->getBeginLoc()