diff mbox series

[pushed] c++: -Wreturn-type with if (true) throw [PR107310]

Message ID 20230314184620.373190-1-jason@redhat.com
State Committed
Commit 71b33f8fb8daa6a7a359f322b24365d9016438fc
Headers
Series [pushed] c++: -Wreturn-type with if (true) throw [PR107310] |

Commit Message

Jason Merrill March 14, 2023, 6:46 p.m. UTC 
  Tested x86_64-pc-linux-gnu, applying to trunk.

-- 8< --

I removed this folding in GCC 12 because it was interfering with an
experiment of richi's, but that never went in and the change causes
regressions, so let's put it back.

This reverts commit r12-5638-ga3e75c1491cd2d.

	PR c++/107310

gcc/cp/ChangeLog:

	* cp-gimplify.cc (genericize_if_stmt): Restore folding
	of constant conditions.

gcc/testsuite/ChangeLog:

	* c-c++-common/Wimplicit-fallthrough-39.c: Adjust warning.
	* g++.dg/warn/Wreturn-6.C: New test.
---
 gcc/cp/cp-gimplify.cc                            |  6 ++++++
 .../c-c++-common/Wimplicit-fallthrough-39.c      |  4 ++--
 gcc/testsuite/g++.dg/warn/Wreturn-6.C            | 16 ++++++++++++++++
 3 files changed, 24 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/warn/Wreturn-6.C


base-commit: 42630fadbe248717859d61c0244c821c32b4e52c
diff mbox series

Patch

diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
index b995b4f81a5..4fecd5616bd 100644
--- a/gcc/cp/cp-gimplify.cc
+++ b/gcc/cp/cp-gimplify.cc
@@ -190,6 +190,12 @@  genericize_if_stmt (tree *stmt_p)
     }
   else if (IF_STMT_CONSTEXPR_P (stmt))
     stmt = integer_nonzerop (cond) ? then_ : else_;
+  /* ??? This optimization doesn't seem to belong here, but removing it
+     causes -Wreturn-type regressions (e.g. 107310).  */
+  else if (integer_nonzerop (cond) && !TREE_SIDE_EFFECTS (else_))
+    stmt = then_;
+  else if (integer_zerop (cond) && !TREE_SIDE_EFFECTS (then_))
+    stmt = else_;
   else
     stmt = build3 (COND_EXPR, void_type_node, cond, then_, else_);
   protected_set_expr_location_if_unset (stmt, locus);
diff --git a/gcc/testsuite/c-c++-common/Wimplicit-fallthrough-39.c b/gcc/testsuite/c-c++-common/Wimplicit-fallthrough-39.c
index da4aef3a318..d06bc0db5ec 100644
--- a/gcc/testsuite/c-c++-common/Wimplicit-fallthrough-39.c
+++ b/gcc/testsuite/c-c++-common/Wimplicit-fallthrough-39.c
@@ -37,8 +37,8 @@  fn2 (int n)
   switch (n)
     {
     case 0:
-      if (1)	  /* { dg-warning "statement may fall through" "" { target c++ } } */
-       	n++;	  /* { dg-warning "statement may fall through" "" { target c } } */
+      if (1)
+       	n++;	  /* { dg-warning "statement may fall through" } */
     case 1:	  /* { dg-message "here" } */
       return -1;
     }
diff --git a/gcc/testsuite/g++.dg/warn/Wreturn-6.C b/gcc/testsuite/g++.dg/warn/Wreturn-6.C
new file mode 100644
index 00000000000..85fef0e16df
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wreturn-6.C
@@ -0,0 +1,16 @@ 
+// PR c++/107310
+
+struct f
+{
+  ~f();
+};
+
+int foo(int t) {
+  f g;
+  switch (t) {
+  case 1:
+    return 1;
+  }
+  if (true)
+    throw 1;
+} // { dg-bogus "control reaches end" }