From 5c37f5994d82fdf9b1f1400eb88a4fe05cc1bf9c Mon Sep 17 00:00:00 2001
From: Akim Demaille <akim.demaille@gmail.com>
Date: Sun, 13 Sep 2020 13:37:05 +0200
Subject: [PATCH] glr2.cc: avoid type-punning issues

On the CI, tests fail with GCC 4.6 to GCC 6 as follows:

    tests/synclines.at:440: COLUMNS=1000; export COLUMNS; NO_TERM_HYPERLINKS=1; export NO_TERM_HYPERLINKS;  bison --color=no -fno-caret  -o \"\\\"\".cc \"\\\"\".y
    tests/synclines.at:440: $CXX $CXXFLAGS $CPPFLAGS  $LDFLAGS -o \"\\\"\" \"\\\"\".cc $LIBS
    stderr:
    "\"".cc: In member function 'glr_state& glr_stack_item::getState()':
    "\"".cc:1404:47: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing]
         return *reinterpret_cast<glr_state*>(&raw_);
                                                   ^
    "\"".cc: In member function 'const glr_state& glr_stack_item::getState() const':
    "\"".cc:1408:53: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing]
         return *reinterpret_cast<const glr_state*>(&raw_);
                                                         ^
    "\"".cc: In member function 'semantic_option& glr_stack_item::getOption()':
    "\"".cc:1413:53: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing]
         return *reinterpret_cast<semantic_option*>(&raw_);
                                                         ^
    "\"".cc: In member function 'const semantic_option& glr_stack_item::getOption() const':
    "\"".cc:1417:59: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing]
         return *reinterpret_cast<const semantic_option*>(&raw_);
                                                           ^

See also be6fa942acae21a4a025bac5e339451be6ad136d.

* data/skeletons/glr2.cc (glr_stack_item): Use a temporary void*
variable to avoid type-punning issues with reinterpret_cast.
---
 data/skeletons/glr2.cc | 35 ++++++++++++++++++++++-------------
 1 file changed, 22 insertions(+), 13 deletions(-)

diff --git a/data/skeletons/glr2.cc b/data/skeletons/glr2.cc
index 5f6a5c95..f15ab96d 100644
--- a/data/skeletons/glr2.cc
+++ b/data/skeletons/glr2.cc
@@ -1241,24 +1241,33 @@ public:
       getOption().~semantic_option();
   }
 
-  glr_state& getState() {
-    YYDASSERT(is_state());
-    return *reinterpret_cast<glr_state*>(&raw_);
+  glr_state& getState ()
+  {
+    YYDASSERT (is_state ());
+    void *yyp = raw_;
+    return *static_cast<glr_state*> (yyp);
   }
-  const glr_state& getState() const {
-    YYDASSERT(is_state());
-    return *reinterpret_cast<const glr_state*>(&raw_);
+  const glr_state& getState () const
+  {
+    YYDASSERT (is_state());
+    const void *yyp = raw_;
+    return *static_cast<const glr_state*> (yyp);
   }
 
-  semantic_option& getOption() {
-    YYDASSERT(!is_state());
-    return *reinterpret_cast<semantic_option*>(&raw_);
+  semantic_option& getOption ()
+  {
+    YYDASSERT (!is_state ());
+    void *yyp = raw_;
+    return *static_cast<semantic_option*> (yyp);
   }
-  const semantic_option& getOption() const {
-    YYDASSERT(!is_state());
-    return *reinterpret_cast<const semantic_option*>(&raw_);
+  const semantic_option& getOption () const
+  {
+    YYDASSERT (!is_state ());
+    const void *yyp = raw_;
+    return *static_cast<const semantic_option*> (yyp);
   }
-  bool is_state() const {
+  bool is_state () const
+  {
     return is_state_;
   }
  private: