Correct handling of indices into arrays with elements larger than 1 (PR c++/96511)

Resolves:
PR c++/96511 - Incorrect -Wplacement-new on POINTER_PLUS into an array with 4-byte elements
PR middle-end/96384 - bogus -Wstringop-overflow= storing into multidimensional array with index in range

gcc/ChangeLog:

	PR c++/96511
	PR middle-end/96384
	* builtins.c (get_range): Return full range of type when neither
	value nor its range is available.  Fail for ranges inverted due
	to the signedness of offsets.
	(compute_objsize): Handle more special array members.  Handle
	POINTER_PLUS_EXPR and VIEW_CONVERT_EXPR that come up in front end
	code.
	(access_ref::offset_bounded): Define new member function.
	* builtins.h (access_ref::eval): New data member.
	(access_ref::offset_bounded): New member function.
	(access_ref::offset_zero): New member function.
	(compute_objsize): Declare a new overload.
	* gimple-array-bounds.cc (array_bounds_checker::check_array_ref): Use
	enum special_array_member.
	* tree.c (component_ref_size): Use special_array_member.
	* tree.h (special_array_member): Define a new type.
	(component_ref_size): Change signature.

gcc/cp/ChangeLog:

	PR c++/96511
	PR middle-end/96384
	* init.c (warn_placement_new_too_small): Call builtin_objsize instead
	of duplicating what it does.

gcc/testsuite/ChangeLog:

	PR c++/96511
	PR middle-end/96384
	* g++.dg/init/strlen.C: Add expected warning.
	* g++.dg/warn/Wplacement-new-size-1.C: Relax warnings.
	* g++.dg/warn/Wplacement-new-size-2.C: Same.
	* g++.dg/warn/Wplacement-new-size-6.C: Same.
	* gcc.dg/Warray-bounds-58.c: Adjust
	* gcc.dg/Wstringop-overflow-37.c: Same.
	* g++.dg/warn/Wplacement-new-size-7.C: New test.

2 files changed, 26 insertions, 8 deletions

diff --git a/gcc/testsuite/gcc.dg/Warray-bounds-58.c b/gcc/testsuite/gcc.dg/Warray-bounds-58.c
index 7c469e2..849457e5 100644
--- a/gcc/testsuite/gcc.dg/Warray-bounds-58.c
+++ b/gcc/testsuite/gcc.dg/Warray-bounds-58.c
@@ -1,5 +1,5 @@
 /* { dg-do compile }
-   { dg-options "-O2 -Wall" } */
+   { dg-options "-O2 -Wall -Wno-stringop-overread" } */
 
 typedef __SIZE_TYPE__ size_t;
 
@@ -15,7 +15,7 @@ void fa0_extern (void)
 {
   sink (strlen (ea0.a - 2));    // { dg-warning "\\\[-Warray-bounds" }
   sink (strlen (ea0.a - 1));    // { dg-warning "\\\[-Warray-bounds" "pr93514" { xfail *-*-* } }
-  sink (strlen (ea0.a));        // { dg-warning "\\\[-Wstringop-overread" "pr93514" }
+  sink (strlen (ea0.a));        // valid just-past-the-end offset
   sink (strlen (ea0.a + 1));    // { dg-warning "\\\[-Warray-bounds|-Wstringop-overread" }
 }
 
@@ -25,7 +25,7 @@ void fa0_static (void)
 {
   sink (strlen (sa0.a - 2));    // { dg-warning "\\\[-Warray-bounds" }
   sink (strlen (sa0.a - 1));    // { dg-warning "\\\[-Warray-bounds" "pr93514" { xfail *-*-* } }
-  sink (strlen (sa0.a));        // { dg-warning "\\\[-Wstringop-overread" "pr93514" }
+  sink (strlen (sa0.a));        // valid just-past-the-end offset
   sink (strlen (sa0.a + 1));    // { dg-warning "\\\[-Warray-bounds|-Wstringop-overread" }
 }
 
@@ -52,14 +52,14 @@ void fax_static (void)
   sink (strlen (ax0.a - 2));    // { dg-warning "\\\[-Warray-bounds" }
   sink (strlen (ax0.a - 1));    // { dg-warning "\\\[-Warray-bounds" "pr93514" { xfail *-*-* } }
   sink (strlen (ax0.a));
-  sink (strlen (ax0.a + 1));    // { dg-warning "\\\[-Wstringop-overread" "pr93514" }
+  sink (strlen (ax0.a + 1));    // valid just-past-the-end offset
   sink (strlen (ax0.a + 2));    // { dg-warning "\\\[-Warray-bounds|-Wstringop-overread" }
 
   sink (strlen (ax1.a - 2));    // { dg-warning "\\\[-Warray-bounds" }
   sink (strlen (ax1.a - 1));    // { dg-warning "\\\[-Warray-bounds" "pr93514" { xfail *-*-* } }
   sink (strlen (ax1.a));
   sink (strlen (ax1.a + 1));
-  sink (strlen (ax1.a + 2));    // { dg-warning "\\\[-Warray-bounds|-Wstringop-overread" "pr93514" }
+  sink (strlen (ax1.a + 2));    // valid just-past-the-end offset
   sink (strlen (ax1.a + 3));    // { dg-warning "\\\[-Warray-bounds|-Wstringop-overread" }
 
   sink (strlen (ax2.a - 2));    // { dg-warning "\\\[-Warray-bounds" }
@@ -67,7 +67,7 @@ void fax_static (void)
   sink (strlen (ax2.a));
   sink (strlen (ax2.a + 1));
   sink (strlen (ax2.a + 2));
-  sink (strlen (ax2.a + 3));    // { dg-warning "\\\[-Warray-bounds|-Wstringop-overread" "pr93514" }
+  sink (strlen (ax2.a + 3));    // valid just-past-the-end offset
   sink (strlen (ax2.a + 4));    // { dg-warning "\\\[-Warray-bounds|-Wstringop-overread" }
 
   sink (strlen (ax3.a - 2));    // { dg-warning "\\\[-Warray-bounds" }
@@ -76,6 +76,6 @@ void fax_static (void)
   sink (strlen (ax3.a + 1));
   sink (strlen (ax3.a + 2));
   sink (strlen (ax3.a + 3));
-  sink (strlen (ax3.a + 4));    // { dg-warning "\\\[-Warray-bounds|-Wstringop-overread" "pr93514" }
+  sink (strlen (ax3.a + 4));    // valid just-past-the-end offset
   sink (strlen (ax3.a + 5));    // { dg-warning "\\\[-Warray-bounds|-Wstringop-overread" }
 }
diff --git a/gcc/testsuite/gcc.dg/Wstringop-overflow-37.c b/gcc/testsuite/gcc.dg/Wstringop-overflow-37.c
index 339f904..46f8fed 100644
--- a/gcc/testsuite/gcc.dg/Wstringop-overflow-37.c
+++ b/gcc/testsuite/gcc.dg/Wstringop-overflow-37.c
@@ -185,6 +185,18 @@ void test_note (const char *s)
   }
 
   {
+    char a[1][1][2];                    // { dg-message "at offset 2 into " }
+    strncpy (a[0][1], s, 3);            // { dg-warning "writing 3 bytes into a region of size 0 " }
+    sink (a);
+  }
+
+  {
+    char a[1][2][2];                    // { dg-message "destination object" }
+    strncpy (a[0][0], s, 3);            // { dg-warning "writing 3 bytes into a region of size 2 " }
+    sink (a);
+  }
+
+  {
     char a[1][2][2];                    // { dg-message "at offset 2 into " }
     strncpy (a[0][1], s, 3);            // { dg-warning "writing 3 bytes into a region of size 2 " }
     sink (a);
@@ -192,7 +204,13 @@ void test_note (const char *s)
 
   {
     char a[1][2][2];                    // { dg-message "at offset 4 into " }
-    strncpy (a[1][0], s, 3);            // { dg-warning "writing 3 bytes into a region of size 2 " }
+    strncpy (a[1][0], s, 3);            // { dg-warning "writing 3 bytes into a region of size 0 " }
+    sink (a);
+  }
+
+  {
+    char a[2][1][2];                    // { dg-message "at offset 2 into " }
+    strncpy (a[0][1], s, 3);            // { dg-warning "writing 3 bytes into a region of size 0 " }
     sink (a);
   }