From 006783f4b165dff25aae3697920fcf54754dddd4 Mon Sep 17 00:00:00 2001
From: Jason Merrill <jason@redhat.com>
Date: Tue, 13 Apr 2021 16:18:54 -0400
Subject: [PATCH] c++: debug location of variable cleanups [PR88742]

PR49951 complained about the debugger jumping back to the declaration of a
local variable when we run its destructor.  That was fixed in 4.7, but broke
again in 4.8.  PR58123 fixed an inconsistency in the behavior, but not the
jumping around.  This patch addresses the issue by setting EXPR_LOCATION on
a cleanup destructor call to the location of the closing brace of the
compound-statement, or whatever token ends the scope of the variable.

The change to cp_parser_compound_statement is so input_location is the }
rather than the ; of the last substatement.

gcc/cp/ChangeLog:

	PR c++/88742
	PR c++/49951
	PR c++/58123
	* semantics.c (set_cleanup_locs): New.
	(do_poplevel): Call it.
	* parser.c (cp_parser_compound_statement): Consume the }
	before finish_compound_stmt.

gcc/testsuite/ChangeLog:

	PR c++/88742
	* g++.dg/debug/cleanup1.C: New test.
	* c-c++-common/Wimplicit-fallthrough-6.c: Adjust diagnostic line.
	* c-c++-common/Wimplicit-fallthrough-7.c: Likewise.
	* g++.dg/cpp2a/constexpr-dtor3.C: Likewise.
	* g++.dg/ext/constexpr-attr-cleanup1.C: Likewise.
	* g++.dg/tm/inherit2.C: Likewise.
	* g++.dg/tm/unsafe1.C: Likewise.
	* g++.dg/warn/Wimplicit-fallthrough-1.C: Likewise.
	* g++.dg/gcov/gcov-2.C: Adjust coverage counts.
---
 gcc/cp/parser.c                               |  5 ++-
 gcc/cp/semantics.c                            | 19 +++++++++
 .../c-c++-common/Wimplicit-fallthrough-6.c    | 16 ++++----
 .../c-c++-common/Wimplicit-fallthrough-7.c    |  4 +-
 gcc/testsuite/g++.dg/cpp2a/constexpr-dtor3.C  |  4 +-
 gcc/testsuite/g++.dg/debug/cleanup1.C         | 41 +++++++++++++++++++
 .../g++.dg/ext/constexpr-attr-cleanup1.C      |  4 +-
 gcc/testsuite/g++.dg/gcov/gcov-2.C            |  4 +-
 gcc/testsuite/g++.dg/tm/inherit2.C            |  4 +-
 gcc/testsuite/g++.dg/tm/unsafe1.C             |  4 +-
 .../g++.dg/warn/Wimplicit-fallthrough-1.C     |  4 +-
 11 files changed, 85 insertions(+), 24 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/debug/cleanup1.C

diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 8b7801b2be73..aec3aa3587ff 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -12126,11 +12126,12 @@ cp_parser_compound_statement (cp_parser *parser, tree in_statement_expr,
   if (function_body)
     maybe_splice_retval_cleanup (compound_stmt);
 
-  /* Finish the compound-statement.  */
-  finish_compound_stmt (compound_stmt);
   /* Consume the `}'.  */
   braces.require_close (parser);
 
+  /* Finish the compound-statement.  */
+  finish_compound_stmt (compound_stmt);
+
   return compound_stmt;
 }
 
diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
index 8eaaaefe2d61..125772238d3c 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -602,6 +602,22 @@ add_decl_expr (tree decl)
   add_stmt (r);
 }
 
+/* Set EXPR_LOCATION of the cleanups of any CLEANUP_STMT in STMTS to LOC.  */
+
+static void
+set_cleanup_locs (tree stmts, location_t loc)
+{
+  if (TREE_CODE (stmts) == CLEANUP_STMT)
+    {
+      protected_set_expr_location (CLEANUP_EXPR (stmts), loc);
+      set_cleanup_locs (CLEANUP_BODY (stmts), loc);
+    }
+  else if (TREE_CODE (stmts) == STATEMENT_LIST)
+    for (tree_stmt_iterator i = tsi_start (stmts);
+	 !tsi_end_p (i); tsi_next (&i))
+      set_cleanup_locs (tsi_stmt (i), loc);
+}
+
 /* Finish a scope.  */
 
 tree
@@ -614,6 +630,9 @@ do_poplevel (tree stmt_list)
 
   stmt_list = pop_stmt_list (stmt_list);
 
+  /* input_location is the last token of the scope, usually a }.  */
+  set_cleanup_locs (stmt_list, input_location);
+
   if (!processing_template_decl)
     {
       stmt_list = c_build_bind_expr (input_location, block, stmt_list);
diff --git a/gcc/testsuite/c-c++-common/Wimplicit-fallthrough-6.c b/gcc/testsuite/c-c++-common/Wimplicit-fallthrough-6.c
index 32d5febda830..9593f670709e 100644
--- a/gcc/testsuite/c-c++-common/Wimplicit-fallthrough-6.c
+++ b/gcc/testsuite/c-c++-common/Wimplicit-fallthrough-6.c
@@ -121,8 +121,8 @@ L1:
 	int j = 0;
 	bar (j);
 	if (j == 8)
-	  return; /* { dg-warning "statement may fall through" "" { target c++ } } */
-      }
+	  return;
+      } /* { dg-warning "statement may fall through" "" { target c++ } } */
     case 2:
       bar (99);
     }
@@ -151,8 +151,8 @@ L1:
 	if (j == 8)
 	  bar (1);
 	else
-	  return; /* { dg-warning "statement may fall through" "" { target c++ } } */
-      }
+	  return;
+      } /* { dg-warning "statement may fall through" "" { target c++ } } */
     case 2:
       bar (99);
     }
@@ -181,8 +181,8 @@ L1:
 	if (j == 8)
 	  bar (1);
 	else
-	  bar (2); /* { dg-warning "statement may fall through" "" { target c++ } } */
-      }
+	  bar (2);
+      } /* { dg-warning "statement may fall through" "" { target c++ } } */
     case 2:
       bar (99);
     }
@@ -281,8 +281,8 @@ L1:
     case 1:
       { /* { dg-warning "statement may fall through" "" { target c } } */
 	int j = 9;
-	switch (j); /* { dg-warning "statement may fall through" "" { target c++ } } */
-      }
+	switch (j);
+      } /* { dg-warning "statement may fall through" "" { target c++ } } */
     case 2:
       bar (99);
     }
diff --git a/gcc/testsuite/c-c++-common/Wimplicit-fallthrough-7.c b/gcc/testsuite/c-c++-common/Wimplicit-fallthrough-7.c
index a602216fa730..343b62508072 100644
--- a/gcc/testsuite/c-c++-common/Wimplicit-fallthrough-7.c
+++ b/gcc/testsuite/c-c++-common/Wimplicit-fallthrough-7.c
@@ -22,8 +22,8 @@ f (int i)
     {
     case 1:
       { /* { dg-warning "statement may fall through" "" { target c } } */
-	int a[i]; /* { dg-warning "statement may fall through" "" { target c++ } } */
-      }
+	int a[i];
+      } /* { dg-warning "statement may fall through" "" { target c++ } } */
     case 2:
       bar (99);
     }
diff --git a/gcc/testsuite/g++.dg/cpp2a/constexpr-dtor3.C b/gcc/testsuite/g++.dg/cpp2a/constexpr-dtor3.C
index 193ae93933de..7700bb7b0365 100644
--- a/gcc/testsuite/g++.dg/cpp2a/constexpr-dtor3.C
+++ b/gcc/testsuite/g++.dg/cpp2a/constexpr-dtor3.C
@@ -149,9 +149,9 @@ constexpr int x3 = f3 ();
 constexpr int
 f4 ()
 {
-  W7 w13 = 5;			// { dg-message "in 'constexpr' expansion of" }
+  W7 w13 = 5;
   return 0;
-}
+}			// { dg-message "in 'constexpr' expansion of" }
 
 constexpr int x4 = f4 ();	// { dg-message "in 'constexpr' expansion of" }
 
diff --git a/gcc/testsuite/g++.dg/debug/cleanup1.C b/gcc/testsuite/g++.dg/debug/cleanup1.C
new file mode 100644
index 000000000000..ae0515aef7b9
--- /dev/null
+++ b/gcc/testsuite/g++.dg/debug/cleanup1.C
@@ -0,0 +1,41 @@
+// PR c++/88742
+// { dg-additional-options -fdump-tree-gimple-lineno }
+
+
+class C {
+public:
+  C() {}
+  ~C() {}
+  operator int() { return 1; }
+};
+
+int main() {
+  C a;
+  C b;
+  C c;
+
+  if (C e = C())
+    {
+      if (C d = C())
+        {
+        }
+      else
+        {
+          return 42;
+        } // { dg-final { scan-tree-dump-times ":25:9. C::~C" 1 "gimple" } }
+    } // { dg-final { scan-tree-dump-times ":26:5. C::~C" 1 "gimple" } }
+
+  while (C f = C())
+    {
+      break;
+    } // { dg-final { scan-tree-dump-times ":31:5. C::~C" 1 "gimple" } }
+
+  for (C h = C(); C i = C(); )
+    break; // { dg-final { scan-tree-dump-times ":34:10. C::~C" 2 "gimple" } }
+
+  switch (C g = C())
+    {
+    default:
+      break;
+    } // { dg-final { scan-tree-dump-times ":40:5. C::~C" 1 "gimple" } }
+} // { dg-final { scan-tree-dump-times ":41:1. C::~C" 3 "gimple" } }
diff --git a/gcc/testsuite/g++.dg/ext/constexpr-attr-cleanup1.C b/gcc/testsuite/g++.dg/ext/constexpr-attr-cleanup1.C
index b6e7c6913673..ab5fd17e815a 100644
--- a/gcc/testsuite/g++.dg/ext/constexpr-attr-cleanup1.C
+++ b/gcc/testsuite/g++.dg/ext/constexpr-attr-cleanup1.C
@@ -15,9 +15,9 @@ cleanup2 (int *x)
 constexpr bool
 foo ()
 {
-  int a __attribute__((cleanup (cleanup))) = 1;	// { dg-message "in 'constexpr' expansion of" }
+  int a __attribute__((cleanup (cleanup))) = 1;
   return true;
-}
+} // { dg-message "in 'constexpr' expansion of" }
 
 constexpr bool
 bar ()
diff --git a/gcc/testsuite/g++.dg/gcov/gcov-2.C b/gcc/testsuite/g++.dg/gcov/gcov-2.C
index 6d002f5d2cd0..2b4cdd844e95 100644
--- a/gcc/testsuite/g++.dg/gcov/gcov-2.C
+++ b/gcc/testsuite/g++.dg/gcov/gcov-2.C
@@ -20,9 +20,9 @@ private:
 
 void foo()
 {
-  C c;					/* count(2) */
+  C c;					/* count(1) */
   c.seti (1);				/* count(1) */
-}
+}					/* count(1) */
 
 int main()
 {
diff --git a/gcc/testsuite/g++.dg/tm/inherit2.C b/gcc/testsuite/g++.dg/tm/inherit2.C
index 3b696a9ffb68..366f9b30e909 100644
--- a/gcc/testsuite/g++.dg/tm/inherit2.C
+++ b/gcc/testsuite/g++.dg/tm/inherit2.C
@@ -26,8 +26,8 @@ int main()
     B b; // ok
     D1 d1; // ok
     B& b1 = d1;
-    D2 x; // { dg-error "" "destructor of D2 is not transaction-safe" }
+    D2 x;
     b1.f(); // ok, calls D1::f()
     delete b2; // undefined behavior: calls unsafe destructor of D2
-  }
+  } // { dg-error "" "destructor of D2 is not transaction-safe" }
 }
diff --git a/gcc/testsuite/g++.dg/tm/unsafe1.C b/gcc/testsuite/g++.dg/tm/unsafe1.C
index 49dd564894a5..710fb1a30313 100644
--- a/gcc/testsuite/g++.dg/tm/unsafe1.C
+++ b/gcc/testsuite/g++.dg/tm/unsafe1.C
@@ -5,8 +5,8 @@ struct S {
   virtual ~S();
 };
 void f() transaction_safe {
-  S s;		     // { dg-error "unsafe" "invocation of unsafe destructor" }
-}
+  S s;
+} // { dg-error "unsafe" "invocation of unsafe destructor" }
 
 int g(int x) { // is transaction-safe
   if (x <= 0)
diff --git a/gcc/testsuite/g++.dg/warn/Wimplicit-fallthrough-1.C b/gcc/testsuite/g++.dg/warn/Wimplicit-fallthrough-1.C
index 053ed6885c59..b5ebd3daaad9 100644
--- a/gcc/testsuite/g++.dg/warn/Wimplicit-fallthrough-1.C
+++ b/gcc/testsuite/g++.dg/warn/Wimplicit-fallthrough-1.C
@@ -25,8 +25,8 @@ fn2 ()
   switch (0) {
   case 0:
   {
-    A b; // { dg-warning "statement may fall through" }
-  }
+    A b;
+  } // { dg-warning "statement may fall through" }
   default:
     a = 0;
   }
-- 
2.47.3