[PATCH] c++: fix ICE with sizeof in a template [PR112869]

[PATCH] c++: fix ICE with sizeof in a template [PR112869]

[Marek Polacek]

Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?

-- >8 --
This test shows that we cannot clear *walk_subtrees in
cp_fold_immediate_r when we're in_immediate_context, because that,
as the comment says, affects cp_fold_r as well.  Here we had an
expression with

  min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount), (long int) <<< Unknown tree: sizeof_expr
    (int) <<< error >>> >>>)

as its sub-expression, and we never evaluated that into

  min ((long int) bytecount, 4)

so the SIZEOF_EXPR leaked into the middle end.

(There's still one *walk_subtrees = 0; in cp_fold_immediate_r, but that
one should be OK.)

	PR c++/112869

gcc/cp/ChangeLog:

	* cp-gimplify.cc (cp_fold_immediate_r): Don't clear *walk_subtrees
	for unevaluated operands.

gcc/testsuite/ChangeLog:

	* g++.dg/template/sizeof18.C: New test.
---
 gcc/cp/cp-gimplify.cc                    | 8 ++------
 gcc/testsuite/g++.dg/template/sizeof18.C | 8 ++++++++
 2 files changed, 10 insertions(+), 6 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/template/sizeof18.C

diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
index 5abb91bbdd3..46c3eb91853 100644
--- a/gcc/cp/cp-gimplify.cc
+++ b/gcc/cp/cp-gimplify.cc
@@ -1177,13 +1177,9 @@ cp_fold_immediate_r (tree *stmt_p, int *walk_subtrees, void *data_)
 				   ? tf_error : tf_none);
   const tree_code code = TREE_CODE (stmt);
 
-  /* No need to look into types or unevaluated operands.
-     NB: This affects cp_fold_r as well.  */
+  /* No need to look into types or unevaluated operands.  */
   if (TYPE_P (stmt) || unevaluated_p (code) || in_immediate_context ())
-    {
-      *walk_subtrees = 0;
-      return NULL_TREE;
-    }
+    return NULL_TREE;
 
   tree decl = NULL_TREE;
   bool call_p = false;
diff --git a/gcc/testsuite/g++.dg/template/sizeof18.C b/gcc/testsuite/g++.dg/template/sizeof18.C
new file mode 100644
index 00000000000..afba9946258
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/sizeof18.C
@@ -0,0 +1,8 @@
+// PR c++/112869
+// { dg-do compile }
+
+void min(long, long);
+template <class T> void Binaryread(int &, T, unsigned long);
+template <> void Binaryread(int &, float, unsigned long bytecount) {
+  min(bytecount, sizeof(int));
+}

base-commit: 9c3a880feecf81c310b4ade210fbd7004c9aece7
-- 
2.43.0

Re: [PATCH] c++: fix ICE with sizeof in a template [PR112869]

[Jason Merrill]

On 12/5/23 15:31, Marek Polacek wrote:
> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> 
> -- >8 --
> This test shows that we cannot clear *walk_subtrees in
> cp_fold_immediate_r when we're in_immediate_context, because that,
> as the comment says, affects cp_fold_r as well.  Here we had an
> expression with
> 
>    min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount), (long int) <<< Unknown tree: sizeof_expr
>      (int) <<< error >>> >>>)
> 
> as its sub-expression, and we never evaluated that into
> 
>    min ((long int) bytecount, 4)
> 
> so the SIZEOF_EXPR leaked into the middle end.
> 
> (There's still one *walk_subtrees = 0; in cp_fold_immediate_r, but that
> one should be OK.)
> 
> 	PR c++/112869
> 
> gcc/cp/ChangeLog:
> 
> 	* cp-gimplify.cc (cp_fold_immediate_r): Don't clear *walk_subtrees
> 	for unevaluated operands.

I agree that we want this change for in_immediate_context (), but I 
don't see why we want it for TYPE_P or unevaluated_p (code) or 
cp_unevaluated_operand?

> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/template/sizeof18.C: New test.
> ---
>   gcc/cp/cp-gimplify.cc                    | 8 ++------
>   gcc/testsuite/g++.dg/template/sizeof18.C | 8 ++++++++
>   2 files changed, 10 insertions(+), 6 deletions(-)
>   create mode 100644 gcc/testsuite/g++.dg/template/sizeof18.C
> 
> diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
> index 5abb91bbdd3..46c3eb91853 100644
> --- a/gcc/cp/cp-gimplify.cc
> +++ b/gcc/cp/cp-gimplify.cc
> @@ -1177,13 +1177,9 @@ cp_fold_immediate_r (tree *stmt_p, int *walk_subtrees, void *data_)
>   				   ? tf_error : tf_none);
>     const tree_code code = TREE_CODE (stmt);
>   
> -  /* No need to look into types or unevaluated operands.
> -     NB: This affects cp_fold_r as well.  */
> +  /* No need to look into types or unevaluated operands.  */
>     if (TYPE_P (stmt) || unevaluated_p (code) || in_immediate_context ())
> -    {
> -      *walk_subtrees = 0;
> -      return NULL_TREE;
> -    }
> +    return NULL_TREE;
>   
>     tree decl = NULL_TREE;
>     bool call_p = false;
> diff --git a/gcc/testsuite/g++.dg/template/sizeof18.C b/gcc/testsuite/g++.dg/template/sizeof18.C
> new file mode 100644
> index 00000000000..afba9946258
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/template/sizeof18.C
> @@ -0,0 +1,8 @@
> +// PR c++/112869
> +// { dg-do compile }
> +
> +void min(long, long);
> +template <class T> void Binaryread(int &, T, unsigned long);
> +template <> void Binaryread(int &, float, unsigned long bytecount) {
> +  min(bytecount, sizeof(int));
> +}
> 
> base-commit: 9c3a880feecf81c310b4ade210fbd7004c9aece7

[PATCH v2] c++: fix ICE with sizeof in a template [PR112869]

[Marek Polacek]

On Fri, Dec 08, 2023 at 12:09:18PM -0500, Jason Merrill wrote:
> On 12/5/23 15:31, Marek Polacek wrote:
> > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> > 
> > -- >8 --
> > This test shows that we cannot clear *walk_subtrees in
> > cp_fold_immediate_r when we're in_immediate_context, because that,
> > as the comment says, affects cp_fold_r as well.  Here we had an
> > expression with
> > 
> >    min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount), (long int) <<< Unknown tree: sizeof_expr
> >      (int) <<< error >>> >>>)
> > 
> > as its sub-expression, and we never evaluated that into
> > 
> >    min ((long int) bytecount, 4)
> > 
> > so the SIZEOF_EXPR leaked into the middle end.
> > 
> > (There's still one *walk_subtrees = 0; in cp_fold_immediate_r, but that
> > one should be OK.)
> > 
> > 	PR c++/112869
> > 
> > gcc/cp/ChangeLog:
> > 
> > 	* cp-gimplify.cc (cp_fold_immediate_r): Don't clear *walk_subtrees
> > 	for unevaluated operands.
> 
> I agree that we want this change for in_immediate_context (), but I don't
> see why we want it for TYPE_P or unevaluated_p (code) or
> cp_unevaluated_operand?

No particular reason, just paranoia.  How's this?

Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?

-- >8 --
This test shows that we cannot clear *walk_subtrees in
cp_fold_immediate_r when we're in_immediate_context, because that,
as the comment says, affects cp_fold_r as well.  Here we had an
expression with

  min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount), (long int) <<< Unknown tree: sizeof_expr
    (int) <<< error >>> >>>)

as its sub-expression, and we never evaluated that into

  min ((long int) bytecount, 4)

so the SIZEOF_EXPR leaked into the middle end.

(There's still one *walk_subtrees = 0; in cp_fold_immediate_r, but that
one should be OK.)

	PR c++/112869

gcc/cp/ChangeLog:

	* cp-gimplify.cc (cp_fold_immediate_r): Don't clear *walk_subtrees
	for in_immediate_context.

gcc/testsuite/ChangeLog:

	* g++.dg/template/sizeof18.C: New test.
---
 gcc/cp/cp-gimplify.cc                    | 6 +++++-
 gcc/testsuite/g++.dg/template/sizeof18.C | 8 ++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.dg/template/sizeof18.C

diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
index 5abb91bbdd3..6af7c787372 100644
--- a/gcc/cp/cp-gimplify.cc
+++ b/gcc/cp/cp-gimplify.cc
@@ -1179,11 +1179,15 @@ cp_fold_immediate_r (tree *stmt_p, int *walk_subtrees, void *data_)
 
   /* No need to look into types or unevaluated operands.
      NB: This affects cp_fold_r as well.  */
-  if (TYPE_P (stmt) || unevaluated_p (code) || in_immediate_context ())
+  if (TYPE_P (stmt) || unevaluated_p (code))
     {
       *walk_subtrees = 0;
       return NULL_TREE;
     }
+  else if (in_immediate_context ())
+    /* Don't clear *walk_subtrees here: we still need to walk the subtrees
+       of SIZEOF_EXPR and similar.  */
+    return NULL_TREE;
 
   tree decl = NULL_TREE;
   bool call_p = false;
diff --git a/gcc/testsuite/g++.dg/template/sizeof18.C b/gcc/testsuite/g++.dg/template/sizeof18.C
new file mode 100644
index 00000000000..afba9946258
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/sizeof18.C
@@ -0,0 +1,8 @@
+// PR c++/112869
+// { dg-do compile }
+
+void min(long, long);
+template <class T> void Binaryread(int &, T, unsigned long);
+template <> void Binaryread(int &, float, unsigned long bytecount) {
+  min(bytecount, sizeof(int));
+}

base-commit: d468718c9a097aeb8794fb1a2df6db2c1064d7f7
-- 
2.43.0

Re: [PATCH v2] c++: fix ICE with sizeof in a template [PR112869]

[Jason Merrill]

On 12/8/23 16:15, Marek Polacek wrote:
> On Fri, Dec 08, 2023 at 12:09:18PM -0500, Jason Merrill wrote:
>> On 12/5/23 15:31, Marek Polacek wrote:
>>> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
>>>
>>> -- >8 --
>>> This test shows that we cannot clear *walk_subtrees in
>>> cp_fold_immediate_r when we're in_immediate_context, because that,
>>> as the comment says, affects cp_fold_r as well.  Here we had an
>>> expression with
>>>
>>>     min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount), (long int) <<< Unknown tree: sizeof_expr
>>>       (int) <<< error >>> >>>)
>>>
>>> as its sub-expression, and we never evaluated that into
>>>
>>>     min ((long int) bytecount, 4)
>>>
>>> so the SIZEOF_EXPR leaked into the middle end.
>>>
>>> (There's still one *walk_subtrees = 0; in cp_fold_immediate_r, but that
>>> one should be OK.)
>>>
>>> 	PR c++/112869
>>>
>>> gcc/cp/ChangeLog:
>>>
>>> 	* cp-gimplify.cc (cp_fold_immediate_r): Don't clear *walk_subtrees
>>> 	for unevaluated operands.
>>
>> I agree that we want this change for in_immediate_context (), but I don't
>> see why we want it for TYPE_P or unevaluated_p (code) or
>> cp_unevaluated_operand?
> 
> No particular reason, just paranoia.  How's this?
> 
> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> 
> -- >8 --
> This test shows that we cannot clear *walk_subtrees in
> cp_fold_immediate_r when we're in_immediate_context, because that,
> as the comment says, affects cp_fold_r as well.  Here we had an
> expression with
> 
>    min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount), (long int) <<< Unknown tree: sizeof_expr
>      (int) <<< error >>> >>>)
> 
> as its sub-expression, and we never evaluated that into
> 
>    min ((long int) bytecount, 4)
> 
> so the SIZEOF_EXPR leaked into the middle end.
> 
> (There's still one *walk_subtrees = 0; in cp_fold_immediate_r, but that
> one should be OK.)
> 
> 	PR c++/112869
> 
> gcc/cp/ChangeLog:
> 
> 	* cp-gimplify.cc (cp_fold_immediate_r): Don't clear *walk_subtrees
> 	for in_immediate_context.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/template/sizeof18.C: New test.
> ---
>   gcc/cp/cp-gimplify.cc                    | 6 +++++-
>   gcc/testsuite/g++.dg/template/sizeof18.C | 8 ++++++++
>   2 files changed, 13 insertions(+), 1 deletion(-)
>   create mode 100644 gcc/testsuite/g++.dg/template/sizeof18.C
> 
> diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
> index 5abb91bbdd3..6af7c787372 100644
> --- a/gcc/cp/cp-gimplify.cc
> +++ b/gcc/cp/cp-gimplify.cc
> @@ -1179,11 +1179,15 @@ cp_fold_immediate_r (tree *stmt_p, int *walk_subtrees, void *data_)
>   
>     /* No need to look into types or unevaluated operands.
>        NB: This affects cp_fold_r as well.  */
> -  if (TYPE_P (stmt) || unevaluated_p (code) || in_immediate_context ())
> +  if (TYPE_P (stmt) || unevaluated_p (code))
>       {
>         *walk_subtrees = 0;
>         return NULL_TREE;
>       }
> +  else if (in_immediate_context ())
> +    /* Don't clear *walk_subtrees here: we still need to walk the subtrees
> +       of SIZEOF_EXPR and similar.  */
> +    return NULL_TREE;
>   
>     tree decl = NULL_TREE;
>     bool call_p = false;
> diff --git a/gcc/testsuite/g++.dg/template/sizeof18.C b/gcc/testsuite/g++.dg/template/sizeof18.C
> new file mode 100644
> index 00000000000..afba9946258
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/template/sizeof18.C
> @@ -0,0 +1,8 @@
> +// PR c++/112869
> +// { dg-do compile }
> +
> +void min(long, long);
> +template <class T> void Binaryread(int &, T, unsigned long);
> +template <> void Binaryread(int &, float, unsigned long bytecount) {
> +  min(bytecount, sizeof(int));
> +}

Hmm, actually, why does the above make a difference for this testcase?

...

It seems that in_immediate_context always returns true in 
cp_fold_function because current_binding_level->kind == 
sk_template_parms.  That seems like a problem.  Maybe for 
cp_fold_immediate_r we only want to check cp_unevaluated_operand or 
DECL_IMMEDIATE_CONTEXT (current_function_decl)?

Jason

[PATCH v3] c++: fix ICE with sizeof in a template [PR112869]

[Marek Polacek]

On Fri, Dec 08, 2023 at 11:09:15PM -0500, Jason Merrill wrote:
> On 12/8/23 16:15, Marek Polacek wrote:
> > On Fri, Dec 08, 2023 at 12:09:18PM -0500, Jason Merrill wrote:
> > > On 12/5/23 15:31, Marek Polacek wrote:
> > > > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> > > > 
> > > > -- >8 --
> > > > This test shows that we cannot clear *walk_subtrees in
> > > > cp_fold_immediate_r when we're in_immediate_context, because that,
> > > > as the comment says, affects cp_fold_r as well.  Here we had an
> > > > expression with
> > > > 
> > > >     min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount), (long int) <<< Unknown tree: sizeof_expr
> > > >       (int) <<< error >>> >>>)
> > > > 
> > > > as its sub-expression, and we never evaluated that into
> > > > 
> > > >     min ((long int) bytecount, 4)
> > > > 
> > > > so the SIZEOF_EXPR leaked into the middle end.
> > > > 
> > > > (There's still one *walk_subtrees = 0; in cp_fold_immediate_r, but that
> > > > one should be OK.)
> > > > 
> > > > 	PR c++/112869
> > > > 
> > > > gcc/cp/ChangeLog:
> > > > 
> > > > 	* cp-gimplify.cc (cp_fold_immediate_r): Don't clear *walk_subtrees
> > > > 	for unevaluated operands.
> > > 
> > > I agree that we want this change for in_immediate_context (), but I don't
> > > see why we want it for TYPE_P or unevaluated_p (code) or
> > > cp_unevaluated_operand?
> > 
> > No particular reason, just paranoia.  How's this?
> > 
> > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> > 
> > -- >8 --
> > This test shows that we cannot clear *walk_subtrees in
> > cp_fold_immediate_r when we're in_immediate_context, because that,
> > as the comment says, affects cp_fold_r as well.  Here we had an
> > expression with
> > 
> >    min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount), (long int) <<< Unknown tree: sizeof_expr
> >      (int) <<< error >>> >>>)
> > 
> > as its sub-expression, and we never evaluated that into
> > 
> >    min ((long int) bytecount, 4)
> > 
> > so the SIZEOF_EXPR leaked into the middle end.
> > 
> > (There's still one *walk_subtrees = 0; in cp_fold_immediate_r, but that
> > one should be OK.)
> > 
> > 	PR c++/112869
> > 
> > gcc/cp/ChangeLog:
> > 
> > 	* cp-gimplify.cc (cp_fold_immediate_r): Don't clear *walk_subtrees
> > 	for in_immediate_context.
> > 
> > gcc/testsuite/ChangeLog:
> > 
> > 	* g++.dg/template/sizeof18.C: New test.
> > ---
> >   gcc/cp/cp-gimplify.cc                    | 6 +++++-
> >   gcc/testsuite/g++.dg/template/sizeof18.C | 8 ++++++++
> >   2 files changed, 13 insertions(+), 1 deletion(-)
> >   create mode 100644 gcc/testsuite/g++.dg/template/sizeof18.C
> > 
> > diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
> > index 5abb91bbdd3..6af7c787372 100644
> > --- a/gcc/cp/cp-gimplify.cc
> > +++ b/gcc/cp/cp-gimplify.cc
> > @@ -1179,11 +1179,15 @@ cp_fold_immediate_r (tree *stmt_p, int *walk_subtrees, void *data_)
> >     /* No need to look into types or unevaluated operands.
> >        NB: This affects cp_fold_r as well.  */
> > -  if (TYPE_P (stmt) || unevaluated_p (code) || in_immediate_context ())
> > +  if (TYPE_P (stmt) || unevaluated_p (code))
> >       {
> >         *walk_subtrees = 0;
> >         return NULL_TREE;
> >       }
> > +  else if (in_immediate_context ())
> > +    /* Don't clear *walk_subtrees here: we still need to walk the subtrees
> > +       of SIZEOF_EXPR and similar.  */
> > +    return NULL_TREE;
> >     tree decl = NULL_TREE;
> >     bool call_p = false;
> > diff --git a/gcc/testsuite/g++.dg/template/sizeof18.C b/gcc/testsuite/g++.dg/template/sizeof18.C
> > new file mode 100644
> > index 00000000000..afba9946258
> > --- /dev/null
> > +++ b/gcc/testsuite/g++.dg/template/sizeof18.C
> > @@ -0,0 +1,8 @@
> > +// PR c++/112869
> > +// { dg-do compile }
> > +
> > +void min(long, long);
> > +template <class T> void Binaryread(int &, T, unsigned long);
> > +template <> void Binaryread(int &, float, unsigned long bytecount) {
> > +  min(bytecount, sizeof(int));
> > +}
> 
> Hmm, actually, why does the above make a difference for this testcase?
> 
> ...
> 
> It seems that in_immediate_context always returns true in cp_fold_function
> because current_binding_level->kind == sk_template_parms.  That seems like a
> problem.  Maybe for cp_fold_immediate_r we only want to check
> cp_unevaluated_operand or DECL_IMMEDIATE_CONTEXT (current_function_decl)?

Yeah, I suppose that could become an issue.  How about this, then?

Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
-- >8 --
This test shows that we cannot clear *walk_subtrees in
cp_fold_immediate_r when we're in_immediate_context, because that,
as the comment says, affects cp_fold_r as well.  Here we had an
expression with

  min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount), (long int) <<< Unknown tree: sizeof_expr
    (int) <<< error >>> >>>)

as its sub-expression, and we never evaluated that into

  min ((long int) bytecount, 4)

so the SIZEOF_EXPR leaked into the middle end.

(There's still one *walk_subtrees = 0; in cp_fold_immediate_r, but that
one should be OK.)

	PR c++/112869

gcc/cp/ChangeLog:

	* cp-gimplify.cc (cp_fold_immediate_r): Don't clear *walk_subtrees
	in an unevaluated operand or immediate function.

gcc/testsuite/ChangeLog:

	* g++.dg/template/sizeof18.C: New test.
---
 gcc/cp/cp-gimplify.cc                    | 8 +++++++-
 gcc/testsuite/g++.dg/template/sizeof18.C | 8 ++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.dg/template/sizeof18.C

diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
index c307e1b62db..413ebafbd1a 100644
--- a/gcc/cp/cp-gimplify.cc
+++ b/gcc/cp/cp-gimplify.cc
@@ -1179,11 +1179,17 @@ cp_fold_immediate_r (tree *stmt_p, int *walk_subtrees, void *data_)
 
   /* No need to look into types or unevaluated operands.
      NB: This affects cp_fold_r as well.  */
-  if (TYPE_P (stmt) || unevaluated_p (code) || in_immediate_context ())
+  if (TYPE_P (stmt) || unevaluated_p (code))
     {
       *walk_subtrees = 0;
       return NULL_TREE;
     }
+  else if (cp_unevaluated_operand
+	   || (current_function_decl
+	       && DECL_IMMEDIATE_FUNCTION_P (current_function_decl)))
+    /* Don't clear *walk_subtrees here: we still need to walk the subtrees
+       of SIZEOF_EXPR and similar.  */
+    return NULL_TREE;
 
   tree decl = NULL_TREE;
   bool call_p = false;
diff --git a/gcc/testsuite/g++.dg/template/sizeof18.C b/gcc/testsuite/g++.dg/template/sizeof18.C
new file mode 100644
index 00000000000..afba9946258
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/sizeof18.C
@@ -0,0 +1,8 @@
+// PR c++/112869
+// { dg-do compile }
+
+void min(long, long);
+template <class T> void Binaryread(int &, T, unsigned long);
+template <> void Binaryread(int &, float, unsigned long bytecount) {
+  min(bytecount, sizeof(int));
+}

base-commit: cd7d0b4cf789264cd75ab7df5df232dc58061ed7
-- 
2.43.0

Re: [PATCH v3] c++: fix ICE with sizeof in a template [PR112869]

[Jason Merrill]

On 12/12/23 17:48, Marek Polacek wrote:
> On Fri, Dec 08, 2023 at 11:09:15PM -0500, Jason Merrill wrote:
>> On 12/8/23 16:15, Marek Polacek wrote:
>>> On Fri, Dec 08, 2023 at 12:09:18PM -0500, Jason Merrill wrote:
>>>> On 12/5/23 15:31, Marek Polacek wrote:
>>>>> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
>>>>>
>>>>> -- >8 --
>>>>> This test shows that we cannot clear *walk_subtrees in
>>>>> cp_fold_immediate_r when we're in_immediate_context, because that,
>>>>> as the comment says, affects cp_fold_r as well.  Here we had an
>>>>> expression with
>>>>>
>>>>>      min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount), (long int) <<< Unknown tree: sizeof_expr
>>>>>        (int) <<< error >>> >>>)
>>>>>
>>>>> as its sub-expression, and we never evaluated that into
>>>>>
>>>>>      min ((long int) bytecount, 4)
>>>>>
>>>>> so the SIZEOF_EXPR leaked into the middle end.
>>>>>
>>>>> (There's still one *walk_subtrees = 0; in cp_fold_immediate_r, but that
>>>>> one should be OK.)
>>>>>
>>>>> 	PR c++/112869
>>>>>
>>>>> gcc/cp/ChangeLog:
>>>>>
>>>>> 	* cp-gimplify.cc (cp_fold_immediate_r): Don't clear *walk_subtrees
>>>>> 	for unevaluated operands.
>>>>
>>>> I agree that we want this change for in_immediate_context (), but I don't
>>>> see why we want it for TYPE_P or unevaluated_p (code) or
>>>> cp_unevaluated_operand?
>>>
>>> No particular reason, just paranoia.  How's this?
>>>
>>> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
>>>
>>> -- >8 --
>>> This test shows that we cannot clear *walk_subtrees in
>>> cp_fold_immediate_r when we're in_immediate_context, because that,
>>> as the comment says, affects cp_fold_r as well.  Here we had an
>>> expression with
>>>
>>>     min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount), (long int) <<< Unknown tree: sizeof_expr
>>>       (int) <<< error >>> >>>)
>>>
>>> as its sub-expression, and we never evaluated that into
>>>
>>>     min ((long int) bytecount, 4)
>>>
>>> so the SIZEOF_EXPR leaked into the middle end.
>>>
>>> (There's still one *walk_subtrees = 0; in cp_fold_immediate_r, but that
>>> one should be OK.)
>>>
>>> 	PR c++/112869
>>>
>>> gcc/cp/ChangeLog:
>>>
>>> 	* cp-gimplify.cc (cp_fold_immediate_r): Don't clear *walk_subtrees
>>> 	for in_immediate_context.
>>>
>>> gcc/testsuite/ChangeLog:
>>>
>>> 	* g++.dg/template/sizeof18.C: New test.
>>> ---
>>>    gcc/cp/cp-gimplify.cc                    | 6 +++++-
>>>    gcc/testsuite/g++.dg/template/sizeof18.C | 8 ++++++++
>>>    2 files changed, 13 insertions(+), 1 deletion(-)
>>>    create mode 100644 gcc/testsuite/g++.dg/template/sizeof18.C
>>>
>>> diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
>>> index 5abb91bbdd3..6af7c787372 100644
>>> --- a/gcc/cp/cp-gimplify.cc
>>> +++ b/gcc/cp/cp-gimplify.cc
>>> @@ -1179,11 +1179,15 @@ cp_fold_immediate_r (tree *stmt_p, int *walk_subtrees, void *data_)
>>>      /* No need to look into types or unevaluated operands.
>>>         NB: This affects cp_fold_r as well.  */
>>> -  if (TYPE_P (stmt) || unevaluated_p (code) || in_immediate_context ())
>>> +  if (TYPE_P (stmt) || unevaluated_p (code))
>>>        {
>>>          *walk_subtrees = 0;
>>>          return NULL_TREE;
>>>        }
>>> +  else if (in_immediate_context ())
>>> +    /* Don't clear *walk_subtrees here: we still need to walk the subtrees
>>> +       of SIZEOF_EXPR and similar.  */
>>> +    return NULL_TREE;
>>>      tree decl = NULL_TREE;
>>>      bool call_p = false;
>>> diff --git a/gcc/testsuite/g++.dg/template/sizeof18.C b/gcc/testsuite/g++.dg/template/sizeof18.C
>>> new file mode 100644
>>> index 00000000000..afba9946258
>>> --- /dev/null
>>> +++ b/gcc/testsuite/g++.dg/template/sizeof18.C
>>> @@ -0,0 +1,8 @@
>>> +// PR c++/112869
>>> +// { dg-do compile }
>>> +
>>> +void min(long, long);
>>> +template <class T> void Binaryread(int &, T, unsigned long);
>>> +template <> void Binaryread(int &, float, unsigned long bytecount) {
>>> +  min(bytecount, sizeof(int));
>>> +}
>>
>> Hmm, actually, why does the above make a difference for this testcase?
>>
>> ...
>>
>> It seems that in_immediate_context always returns true in cp_fold_function
>> because current_binding_level->kind == sk_template_parms.  That seems like a
>> problem.  Maybe for cp_fold_immediate_r we only want to check
>> cp_unevaluated_operand or DECL_IMMEDIATE_CONTEXT (current_function_decl)?
> 
> Yeah, I suppose that could become an issue.  How about this, then?
> 
> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> -- >8 --
> This test shows that we cannot clear *walk_subtrees in
> cp_fold_immediate_r when we're in_immediate_context, because that,
> as the comment says, affects cp_fold_r as well.  Here we had an
> expression with
> 
>    min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount), (long int) <<< Unknown tree: sizeof_expr
>      (int) <<< error >>> >>>)
> 
> as its sub-expression, and we never evaluated that into
> 
>    min ((long int) bytecount, 4)
> 
> so the SIZEOF_EXPR leaked into the middle end.
> 
> (There's still one *walk_subtrees = 0; in cp_fold_immediate_r, but that
> one should be OK.)
> 
> 	PR c++/112869
> 
> gcc/cp/ChangeLog:
> 
> 	* cp-gimplify.cc (cp_fold_immediate_r): Don't clear *walk_subtrees
> 	in an unevaluated operand or immediate function.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/template/sizeof18.C: New test.
> ---
>   gcc/cp/cp-gimplify.cc                    | 8 +++++++-
>   gcc/testsuite/g++.dg/template/sizeof18.C | 8 ++++++++
>   2 files changed, 15 insertions(+), 1 deletion(-)
>   create mode 100644 gcc/testsuite/g++.dg/template/sizeof18.C
> 
> diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
> index c307e1b62db..413ebafbd1a 100644
> --- a/gcc/cp/cp-gimplify.cc
> +++ b/gcc/cp/cp-gimplify.cc
> @@ -1179,11 +1179,17 @@ cp_fold_immediate_r (tree *stmt_p, int *walk_subtrees, void *data_)
>   
>     /* No need to look into types or unevaluated operands.
>        NB: This affects cp_fold_r as well.  */
> -  if (TYPE_P (stmt) || unevaluated_p (code) || in_immediate_context ())
> +  if (TYPE_P (stmt) || unevaluated_p (code))
>       {
>         *walk_subtrees = 0;
>         return NULL_TREE;
>       }
> +  else if (cp_unevaluated_operand
> +	   || (current_function_decl
> +	       && DECL_IMMEDIATE_FUNCTION_P (current_function_decl)))

It should still be fine to clear *walk_subtrees in these cases; the 
problem I was talking about above was that in_immediate_context was 
returning true for all functions, not just consteval functions.

I think the fix is not adding an else, but rather replacing the 
in_immediate_context call with "unevaluated or consteval cfun".

> +    /* Don't clear *walk_subtrees here: we still need to walk the subtrees
> +       of SIZEOF_EXPR and similar.  */

We shouldn't need to walk subtrees of SIZEOF_EXPR or other unevaluated 
operands, they'll all get cp_folded away.  The bug was that we weren't 
calling cp_fold on the SIZEOF_EXPR itself.

Jason

[PATCH v4] c++: fix ICE with sizeof in a template [PR112869]

[Marek Polacek]

On Wed, Dec 13, 2023 at 03:28:38PM -0500, Jason Merrill wrote:
> On 12/12/23 17:48, Marek Polacek wrote:
> > On Fri, Dec 08, 2023 at 11:09:15PM -0500, Jason Merrill wrote:
> > > On 12/8/23 16:15, Marek Polacek wrote:
> > > > On Fri, Dec 08, 2023 at 12:09:18PM -0500, Jason Merrill wrote:
> > > > > On 12/5/23 15:31, Marek Polacek wrote:
> > > > > > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> > > > > > 
> > > > > > -- >8 --
> > > > > > This test shows that we cannot clear *walk_subtrees in
> > > > > > cp_fold_immediate_r when we're in_immediate_context, because that,
> > > > > > as the comment says, affects cp_fold_r as well.  Here we had an
> > > > > > expression with
> > > > > > 
> > > > > >      min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount), (long int) <<< Unknown tree: sizeof_expr
> > > > > >        (int) <<< error >>> >>>)
> > > > > > 
> > > > > > as its sub-expression, and we never evaluated that into
> > > > > > 
> > > > > >      min ((long int) bytecount, 4)
> > > > > > 
> > > > > > so the SIZEOF_EXPR leaked into the middle end.
> > > > > > 
> > > > > > (There's still one *walk_subtrees = 0; in cp_fold_immediate_r, but that
> > > > > > one should be OK.)
> > > > > > 
> > > > > > 	PR c++/112869
> > > > > > 
> > > > > > gcc/cp/ChangeLog:
> > > > > > 
> > > > > > 	* cp-gimplify.cc (cp_fold_immediate_r): Don't clear *walk_subtrees
> > > > > > 	for unevaluated operands.
> > > > > 
> > > > > I agree that we want this change for in_immediate_context (), but I don't
> > > > > see why we want it for TYPE_P or unevaluated_p (code) or
> > > > > cp_unevaluated_operand?
> > > > 
> > > > No particular reason, just paranoia.  How's this?
> > > > 
> > > > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> > > > 
> > > > -- >8 --
> > > > This test shows that we cannot clear *walk_subtrees in
> > > > cp_fold_immediate_r when we're in_immediate_context, because that,
> > > > as the comment says, affects cp_fold_r as well.  Here we had an
> > > > expression with
> > > > 
> > > >     min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount), (long int) <<< Unknown tree: sizeof_expr
> > > >       (int) <<< error >>> >>>)
> > > > 
> > > > as its sub-expression, and we never evaluated that into
> > > > 
> > > >     min ((long int) bytecount, 4)
> > > > 
> > > > so the SIZEOF_EXPR leaked into the middle end.
> > > > 
> > > > (There's still one *walk_subtrees = 0; in cp_fold_immediate_r, but that
> > > > one should be OK.)
> > > > 
> > > > 	PR c++/112869
> > > > 
> > > > gcc/cp/ChangeLog:
> > > > 
> > > > 	* cp-gimplify.cc (cp_fold_immediate_r): Don't clear *walk_subtrees
> > > > 	for in_immediate_context.
> > > > 
> > > > gcc/testsuite/ChangeLog:
> > > > 
> > > > 	* g++.dg/template/sizeof18.C: New test.
> > > > ---
> > > >    gcc/cp/cp-gimplify.cc                    | 6 +++++-
> > > >    gcc/testsuite/g++.dg/template/sizeof18.C | 8 ++++++++
> > > >    2 files changed, 13 insertions(+), 1 deletion(-)
> > > >    create mode 100644 gcc/testsuite/g++.dg/template/sizeof18.C
> > > > 
> > > > diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
> > > > index 5abb91bbdd3..6af7c787372 100644
> > > > --- a/gcc/cp/cp-gimplify.cc
> > > > +++ b/gcc/cp/cp-gimplify.cc
> > > > @@ -1179,11 +1179,15 @@ cp_fold_immediate_r (tree *stmt_p, int *walk_subtrees, void *data_)
> > > >      /* No need to look into types or unevaluated operands.
> > > >         NB: This affects cp_fold_r as well.  */
> > > > -  if (TYPE_P (stmt) || unevaluated_p (code) || in_immediate_context ())
> > > > +  if (TYPE_P (stmt) || unevaluated_p (code))
> > > >        {
> > > >          *walk_subtrees = 0;
> > > >          return NULL_TREE;
> > > >        }
> > > > +  else if (in_immediate_context ())
> > > > +    /* Don't clear *walk_subtrees here: we still need to walk the subtrees
> > > > +       of SIZEOF_EXPR and similar.  */
> > > > +    return NULL_TREE;
> > > >      tree decl = NULL_TREE;
> > > >      bool call_p = false;
> > > > diff --git a/gcc/testsuite/g++.dg/template/sizeof18.C b/gcc/testsuite/g++.dg/template/sizeof18.C
> > > > new file mode 100644
> > > > index 00000000000..afba9946258
> > > > --- /dev/null
> > > > +++ b/gcc/testsuite/g++.dg/template/sizeof18.C
> > > > @@ -0,0 +1,8 @@
> > > > +// PR c++/112869
> > > > +// { dg-do compile }
> > > > +
> > > > +void min(long, long);
> > > > +template <class T> void Binaryread(int &, T, unsigned long);
> > > > +template <> void Binaryread(int &, float, unsigned long bytecount) {
> > > > +  min(bytecount, sizeof(int));
> > > > +}
> > > 
> > > Hmm, actually, why does the above make a difference for this testcase?
> > > 
> > > ...
> > > 
> > > It seems that in_immediate_context always returns true in cp_fold_function
> > > because current_binding_level->kind == sk_template_parms.  That seems like a
> > > problem.  Maybe for cp_fold_immediate_r we only want to check
> > > cp_unevaluated_operand or DECL_IMMEDIATE_CONTEXT (current_function_decl)?
> > 
> > Yeah, I suppose that could become an issue.  How about this, then?
> > 
> > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> > -- >8 --
> > This test shows that we cannot clear *walk_subtrees in
> > cp_fold_immediate_r when we're in_immediate_context, because that,
> > as the comment says, affects cp_fold_r as well.  Here we had an
> > expression with
> > 
> >    min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount), (long int) <<< Unknown tree: sizeof_expr
> >      (int) <<< error >>> >>>)
> > 
> > as its sub-expression, and we never evaluated that into
> > 
> >    min ((long int) bytecount, 4)
> > 
> > so the SIZEOF_EXPR leaked into the middle end.
> > 
> > (There's still one *walk_subtrees = 0; in cp_fold_immediate_r, but that
> > one should be OK.)
> > 
> > 	PR c++/112869
> > 
> > gcc/cp/ChangeLog:
> > 
> > 	* cp-gimplify.cc (cp_fold_immediate_r): Don't clear *walk_subtrees
> > 	in an unevaluated operand or immediate function.
> > 
> > gcc/testsuite/ChangeLog:
> > 
> > 	* g++.dg/template/sizeof18.C: New test.
> > ---
> >   gcc/cp/cp-gimplify.cc                    | 8 +++++++-
> >   gcc/testsuite/g++.dg/template/sizeof18.C | 8 ++++++++
> >   2 files changed, 15 insertions(+), 1 deletion(-)
> >   create mode 100644 gcc/testsuite/g++.dg/template/sizeof18.C
> > 
> > diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
> > index c307e1b62db..413ebafbd1a 100644
> > --- a/gcc/cp/cp-gimplify.cc
> > +++ b/gcc/cp/cp-gimplify.cc
> > @@ -1179,11 +1179,17 @@ cp_fold_immediate_r (tree *stmt_p, int *walk_subtrees, void *data_)
> >     /* No need to look into types or unevaluated operands.
> >        NB: This affects cp_fold_r as well.  */
> > -  if (TYPE_P (stmt) || unevaluated_p (code) || in_immediate_context ())
> > +  if (TYPE_P (stmt) || unevaluated_p (code))
> >       {
> >         *walk_subtrees = 0;
> >         return NULL_TREE;
> >       }
> > +  else if (cp_unevaluated_operand
> > +	   || (current_function_decl
> > +	       && DECL_IMMEDIATE_FUNCTION_P (current_function_decl)))
> 
> It should still be fine to clear *walk_subtrees in these cases; the problem
> I was talking about above was that in_immediate_context was returning true
> for all functions, not just consteval functions.
> 
> I think the fix is not adding an else, but rather replacing the
> in_immediate_context call with "unevaluated or consteval cfun".

Aha, sorry, I misunderstood what you meant.
 
> > +    /* Don't clear *walk_subtrees here: we still need to walk the subtrees
> > +       of SIZEOF_EXPR and similar.  */
> 
> We shouldn't need to walk subtrees of SIZEOF_EXPR or other unevaluated
> operands, they'll all get cp_folded away.  The bug was that we weren't
> calling cp_fold on the SIZEOF_EXPR itself.

Yes.  I suppose the comment should have read "because of SIZEOF_EXPR".

Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?

-- >8 --
This test shows that we cannot clear *walk_subtrees in
cp_fold_immediate_r when we're in_immediate_context, because that
checks even e.g. sk_template_parms, and, as the comment says, affects
cp_fold_r as well.  Here we had an expression with

  min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount), (long int) <<< Unknown tree: sizeof_expr
    (int) <<< error >>> >>>)

as its sub-expression, and we never evaluated that into

  min ((long int) bytecount, 4)

so the SIZEOF_EXPR leaked into the middle end.  We need to make sure
we are calling cp_fold on the SIZEOF_EXPR.

	PR c++/112869

gcc/cp/ChangeLog:

	* cp-gimplify.cc (cp_fold_immediate_r): Check cp_unevaluated_operand
	and DECL_IMMEDIATE_FUNCTION_P rather than in_immediate_context.

gcc/testsuite/ChangeLog:

	* g++.dg/template/sizeof18.C: New test.
---
 gcc/cp/cp-gimplify.cc                    | 8 +++++++-
 gcc/testsuite/g++.dg/template/sizeof18.C | 8 ++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.dg/template/sizeof18.C

diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
index c307e1b62db..64049f4154e 100644
--- a/gcc/cp/cp-gimplify.cc
+++ b/gcc/cp/cp-gimplify.cc
@@ -1179,7 +1179,13 @@ cp_fold_immediate_r (tree *stmt_p, int *walk_subtrees, void *data_)
 
   /* No need to look into types or unevaluated operands.
      NB: This affects cp_fold_r as well.  */
-  if (TYPE_P (stmt) || unevaluated_p (code) || in_immediate_context ())
+  if (TYPE_P (stmt)
+      || unevaluated_p (code)
+      /* We do not use in_immediate_context here because it checks
+	 more than is desirable, e.g., sk_template_parms.  */
+      || cp_unevaluated_operand
+      || (current_function_decl
+	  && DECL_IMMEDIATE_FUNCTION_P (current_function_decl)))
     {
       *walk_subtrees = 0;
       return NULL_TREE;
diff --git a/gcc/testsuite/g++.dg/template/sizeof18.C b/gcc/testsuite/g++.dg/template/sizeof18.C
new file mode 100644
index 00000000000..afba9946258
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/sizeof18.C
@@ -0,0 +1,8 @@
+// PR c++/112869
+// { dg-do compile }
+
+void min(long, long);
+template <class T> void Binaryread(int &, T, unsigned long);
+template <> void Binaryread(int &, float, unsigned long bytecount) {
+  min(bytecount, sizeof(int));
+}

base-commit: 83088b331cde0843d65d316e554873ef6d7b6bca
-- 
2.43.0

Re: [PATCH v4] c++: fix ICE with sizeof in a template [PR112869]

[Jason Merrill]

On 12/14/23 16:01, Marek Polacek wrote:
> On Wed, Dec 13, 2023 at 03:28:38PM -0500, Jason Merrill wrote:
>> On 12/12/23 17:48, Marek Polacek wrote:
>>> On Fri, Dec 08, 2023 at 11:09:15PM -0500, Jason Merrill wrote:
>>>> On 12/8/23 16:15, Marek Polacek wrote:
>>>>> On Fri, Dec 08, 2023 at 12:09:18PM -0500, Jason Merrill wrote:
>>>>>> On 12/5/23 15:31, Marek Polacek wrote:
>>>>>>> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
>>>>>>>
>>>>>>> -- >8 --
>>>>>>> This test shows that we cannot clear *walk_subtrees in
>>>>>>> cp_fold_immediate_r when we're in_immediate_context, because that,
>>>>>>> as the comment says, affects cp_fold_r as well.  Here we had an
>>>>>>> expression with
>>>>>>>
>>>>>>>       min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount), (long int) <<< Unknown tree: sizeof_expr
>>>>>>>         (int) <<< error >>> >>>)
>>>>>>>
>>>>>>> as its sub-expression, and we never evaluated that into
>>>>>>>
>>>>>>>       min ((long int) bytecount, 4)
>>>>>>>
>>>>>>> so the SIZEOF_EXPR leaked into the middle end.
>>>>>>>
>>>>>>> (There's still one *walk_subtrees = 0; in cp_fold_immediate_r, but that
>>>>>>> one should be OK.)
>>>>>>>
>>>>>>> 	PR c++/112869
>>>>>>>
>>>>>>> gcc/cp/ChangeLog:
>>>>>>>
>>>>>>> 	* cp-gimplify.cc (cp_fold_immediate_r): Don't clear *walk_subtrees
>>>>>>> 	for unevaluated operands.
>>>>>>
>>>>>> I agree that we want this change for in_immediate_context (), but I don't
>>>>>> see why we want it for TYPE_P or unevaluated_p (code) or
>>>>>> cp_unevaluated_operand?
>>>>>
>>>>> No particular reason, just paranoia.  How's this?
>>>>>
>>>>> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
>>>>>
>>>>> -- >8 --
>>>>> This test shows that we cannot clear *walk_subtrees in
>>>>> cp_fold_immediate_r when we're in_immediate_context, because that,
>>>>> as the comment says, affects cp_fold_r as well.  Here we had an
>>>>> expression with
>>>>>
>>>>>      min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount), (long int) <<< Unknown tree: sizeof_expr
>>>>>        (int) <<< error >>> >>>)
>>>>>
>>>>> as its sub-expression, and we never evaluated that into
>>>>>
>>>>>      min ((long int) bytecount, 4)
>>>>>
>>>>> so the SIZEOF_EXPR leaked into the middle end.
>>>>>
>>>>> (There's still one *walk_subtrees = 0; in cp_fold_immediate_r, but that
>>>>> one should be OK.)
>>>>>
>>>>> 	PR c++/112869
>>>>>
>>>>> gcc/cp/ChangeLog:
>>>>>
>>>>> 	* cp-gimplify.cc (cp_fold_immediate_r): Don't clear *walk_subtrees
>>>>> 	for in_immediate_context.
>>>>>
>>>>> gcc/testsuite/ChangeLog:
>>>>>
>>>>> 	* g++.dg/template/sizeof18.C: New test.
>>>>> ---
>>>>>     gcc/cp/cp-gimplify.cc                    | 6 +++++-
>>>>>     gcc/testsuite/g++.dg/template/sizeof18.C | 8 ++++++++
>>>>>     2 files changed, 13 insertions(+), 1 deletion(-)
>>>>>     create mode 100644 gcc/testsuite/g++.dg/template/sizeof18.C
>>>>>
>>>>> diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
>>>>> index 5abb91bbdd3..6af7c787372 100644
>>>>> --- a/gcc/cp/cp-gimplify.cc
>>>>> +++ b/gcc/cp/cp-gimplify.cc
>>>>> @@ -1179,11 +1179,15 @@ cp_fold_immediate_r (tree *stmt_p, int *walk_subtrees, void *data_)
>>>>>       /* No need to look into types or unevaluated operands.
>>>>>          NB: This affects cp_fold_r as well.  */
>>>>> -  if (TYPE_P (stmt) || unevaluated_p (code) || in_immediate_context ())
>>>>> +  if (TYPE_P (stmt) || unevaluated_p (code))
>>>>>         {
>>>>>           *walk_subtrees = 0;
>>>>>           return NULL_TREE;
>>>>>         }
>>>>> +  else if (in_immediate_context ())
>>>>> +    /* Don't clear *walk_subtrees here: we still need to walk the subtrees
>>>>> +       of SIZEOF_EXPR and similar.  */
>>>>> +    return NULL_TREE;
>>>>>       tree decl = NULL_TREE;
>>>>>       bool call_p = false;
>>>>> diff --git a/gcc/testsuite/g++.dg/template/sizeof18.C b/gcc/testsuite/g++.dg/template/sizeof18.C
>>>>> new file mode 100644
>>>>> index 00000000000..afba9946258
>>>>> --- /dev/null
>>>>> +++ b/gcc/testsuite/g++.dg/template/sizeof18.C
>>>>> @@ -0,0 +1,8 @@
>>>>> +// PR c++/112869
>>>>> +// { dg-do compile }
>>>>> +
>>>>> +void min(long, long);
>>>>> +template <class T> void Binaryread(int &, T, unsigned long);
>>>>> +template <> void Binaryread(int &, float, unsigned long bytecount) {
>>>>> +  min(bytecount, sizeof(int));
>>>>> +}
>>>>
>>>> Hmm, actually, why does the above make a difference for this testcase?
>>>>
>>>> ...
>>>>
>>>> It seems that in_immediate_context always returns true in cp_fold_function
>>>> because current_binding_level->kind == sk_template_parms.  That seems like a
>>>> problem.  Maybe for cp_fold_immediate_r we only want to check
>>>> cp_unevaluated_operand or DECL_IMMEDIATE_CONTEXT (current_function_decl)?
>>>
>>> Yeah, I suppose that could become an issue.  How about this, then?
>>>
>>> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
>>> -- >8 --
>>> This test shows that we cannot clear *walk_subtrees in
>>> cp_fold_immediate_r when we're in_immediate_context, because that,
>>> as the comment says, affects cp_fold_r as well.  Here we had an
>>> expression with
>>>
>>>     min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount), (long int) <<< Unknown tree: sizeof_expr
>>>       (int) <<< error >>> >>>)
>>>
>>> as its sub-expression, and we never evaluated that into
>>>
>>>     min ((long int) bytecount, 4)
>>>
>>> so the SIZEOF_EXPR leaked into the middle end.
>>>
>>> (There's still one *walk_subtrees = 0; in cp_fold_immediate_r, but that
>>> one should be OK.)
>>>
>>> 	PR c++/112869
>>>
>>> gcc/cp/ChangeLog:
>>>
>>> 	* cp-gimplify.cc (cp_fold_immediate_r): Don't clear *walk_subtrees
>>> 	in an unevaluated operand or immediate function.
>>>
>>> gcc/testsuite/ChangeLog:
>>>
>>> 	* g++.dg/template/sizeof18.C: New test.
>>> ---
>>>    gcc/cp/cp-gimplify.cc                    | 8 +++++++-
>>>    gcc/testsuite/g++.dg/template/sizeof18.C | 8 ++++++++
>>>    2 files changed, 15 insertions(+), 1 deletion(-)
>>>    create mode 100644 gcc/testsuite/g++.dg/template/sizeof18.C
>>>
>>> diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
>>> index c307e1b62db..413ebafbd1a 100644
>>> --- a/gcc/cp/cp-gimplify.cc
>>> +++ b/gcc/cp/cp-gimplify.cc
>>> @@ -1179,11 +1179,17 @@ cp_fold_immediate_r (tree *stmt_p, int *walk_subtrees, void *data_)
>>>      /* No need to look into types or unevaluated operands.
>>>         NB: This affects cp_fold_r as well.  */
>>> -  if (TYPE_P (stmt) || unevaluated_p (code) || in_immediate_context ())
>>> +  if (TYPE_P (stmt) || unevaluated_p (code))
>>>        {
>>>          *walk_subtrees = 0;
>>>          return NULL_TREE;
>>>        }
>>> +  else if (cp_unevaluated_operand
>>> +	   || (current_function_decl
>>> +	       && DECL_IMMEDIATE_FUNCTION_P (current_function_decl)))
>>
>> It should still be fine to clear *walk_subtrees in these cases; the problem
>> I was talking about above was that in_immediate_context was returning true
>> for all functions, not just consteval functions.
>>
>> I think the fix is not adding an else, but rather replacing the
>> in_immediate_context call with "unevaluated or consteval cfun".
> 
> Aha, sorry, I misunderstood what you meant.
>   
>>> +    /* Don't clear *walk_subtrees here: we still need to walk the subtrees
>>> +       of SIZEOF_EXPR and similar.  */
>>
>> We shouldn't need to walk subtrees of SIZEOF_EXPR or other unevaluated
>> operands, they'll all get cp_folded away.  The bug was that we weren't
>> calling cp_fold on the SIZEOF_EXPR itself.
> 
> Yes.  I suppose the comment should have read "because of SIZEOF_EXPR".
> 
> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?

OK, thanks.

> -- >8 --
> This test shows that we cannot clear *walk_subtrees in
> cp_fold_immediate_r when we're in_immediate_context, because that
> checks even e.g. sk_template_parms, and, as the comment says, affects
> cp_fold_r as well.  Here we had an expression with
> 
>    min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount), (long int) <<< Unknown tree: sizeof_expr
>      (int) <<< error >>> >>>)
> 
> as its sub-expression, and we never evaluated that into
> 
>    min ((long int) bytecount, 4)
> 
> so the SIZEOF_EXPR leaked into the middle end.  We need to make sure
> we are calling cp_fold on the SIZEOF_EXPR.
> 
> 	PR c++/112869
> 
> gcc/cp/ChangeLog:
> 
> 	* cp-gimplify.cc (cp_fold_immediate_r): Check cp_unevaluated_operand
> 	and DECL_IMMEDIATE_FUNCTION_P rather than in_immediate_context.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/template/sizeof18.C: New test.
> ---
>   gcc/cp/cp-gimplify.cc                    | 8 +++++++-
>   gcc/testsuite/g++.dg/template/sizeof18.C | 8 ++++++++
>   2 files changed, 15 insertions(+), 1 deletion(-)
>   create mode 100644 gcc/testsuite/g++.dg/template/sizeof18.C
> 
> diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
> index c307e1b62db..64049f4154e 100644
> --- a/gcc/cp/cp-gimplify.cc
> +++ b/gcc/cp/cp-gimplify.cc
> @@ -1179,7 +1179,13 @@ cp_fold_immediate_r (tree *stmt_p, int *walk_subtrees, void *data_)
>   
>     /* No need to look into types or unevaluated operands.
>        NB: This affects cp_fold_r as well.  */
> -  if (TYPE_P (stmt) || unevaluated_p (code) || in_immediate_context ())
> +  if (TYPE_P (stmt)
> +      || unevaluated_p (code)
> +      /* We do not use in_immediate_context here because it checks
> +	 more than is desirable, e.g., sk_template_parms.  */
> +      || cp_unevaluated_operand
> +      || (current_function_decl
> +	  && DECL_IMMEDIATE_FUNCTION_P (current_function_decl)))
>       {
>         *walk_subtrees = 0;
>         return NULL_TREE;
> diff --git a/gcc/testsuite/g++.dg/template/sizeof18.C b/gcc/testsuite/g++.dg/template/sizeof18.C
> new file mode 100644
> index 00000000000..afba9946258
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/template/sizeof18.C
> @@ -0,0 +1,8 @@
> +// PR c++/112869
> +// { dg-do compile }
> +
> +void min(long, long);
> +template <class T> void Binaryread(int &, T, unsigned long);
> +template <> void Binaryread(int &, float, unsigned long bytecount) {
> +  min(bytecount, sizeof(int));
> +}
> 
> base-commit: 83088b331cde0843d65d316e554873ef6d7b6bca