[gdb/testsuite] Fix gdb.cp/step-and-next-inline.exp with gcc-11

When running test-case gdb.cp/step-and-next-inline.exp with gcc-11, I run
into:
...
KPASS: gdb.cp/step-and-next-inline.exp: no_header: next step 1 \
  (PRMS symtab/25507)
FAIL: gdb.cp/step-and-next-inline.exp: no_header: next step 2
KPASS: gdb.cp/step-and-next-inline.exp: no_header: next step 3 \
  (PRMS symtab/25507)
...

[ Note that I get the same result with gcc-11 and target board
unix/gdb:debug_flags=-gdwarf-4, so this is not a dwarf 4 vs 5 issue. ]

With gcc-10, I have this trace:
...
64        get_alias_set (&xx);
get_alias_set (t=0x601038 <xx>) at step-and-next-inline.cc:51
51        if (t != NULL
40        if (t->x != i)
52            && TREE_TYPE (t).z != 1
43        return x;
53            && TREE_TYPE (t).z != 2
43        return x;
54            && TREE_TYPE (t).z != 3)
43        return x;
main () at step-and-next-inline.cc:65
65        return 0;
...
and with gcc-11, I have instead:
...
64        get_alias_set (&xx);
get_alias_set (t=0x601038 <xx>) at step-and-next-inline.cc:51
51        if (t != NULL
52            && TREE_TYPE (t).z != 1
43        return x;
53            && TREE_TYPE (t).z != 2
43        return x;
54            && TREE_TYPE (t).z != 3)
43        return x;
main () at step-and-next-inline.cc:65
65        return 0;
...
and with clang-10, I have instead:
...
64        get_alias_set (&xx);
get_alias_set (t=0x601034 <xx>) at step-and-next-inline.cc:51
51        if (t != NULL
52            && TREE_TYPE (t).z != 1
53            && TREE_TYPE (t).z != 2
54            && TREE_TYPE (t).z != 3)
51        if (t != NULL
57      }
main () at step-and-next-inline.cc:65
65        return 0;
...

The test-case tries to verify that we don't step into inlined function
tree_check (lines 40-43) (so, with the clang trace we get that right).

The test-case then tries to kfail the problems when using gcc, but this is
done in such a way that the testing still gets out of sync after a failure.
That is: the "next step 2" check that is supposed to match
"TREE_TYPE (t).z != 2" is actually matching "TREE_TYPE (t).z != 1":
...
(gdb) next^M
52            && TREE_TYPE (t).z != 1^M
(gdb) PASS: gdb.cp/step-and-next-inline.exp: no_header: next step 2
...

Fix this by issuing extra nexts to arrive at the required lines.

Tested on x86_64-linux, with gcc-8, gcc-9, gcc-10, gcc-11, clang-8, clang-10
and clang-12.

gdb/testsuite/ChangeLog:

2021-07-22  Tom de Vries  <tdevries@suse.de>

	* gdb.cp/step-and-next-inline.cc (tree_check, get_alias_set, main):
	Tag closing brace with comment.
	* gdb.cp/step-and-next-inline.h: Update to keep identical with
	step-and-next-inline.cc.
	* gdb.cp/step-and-next-inline.exp: Issue extra next when required.

gdb/testsuite/ChangeLog

@@ -1,3 +1,11 @@
+2021-07-22  Tom de Vries  <tdevries@suse.de>
+
+	* gdb.cp/step-and-next-inline.cc (tree_check, get_alias_set, main):
+	Tag closing brace with comment.
+	* gdb.cp/step-and-next-inline.h: Update to keep identical with
+	step-and-next-inline.cc.
+	* gdb.cp/step-and-next-inline.exp: Issue extra next when required.
+
 2021-07-21  Tom de Vries  <tdevries@suse.de>
 
 	* lib/gdb.exp (gcc_major_version): New proc.

gdb/testsuite/gdb.cp/step-and-next-inline.cc

@@ -41,7 +41,7 @@ tree_check (tree *t, int i)
     abort();
   tree *x = t;
   return x;
-}
+} // tree-check
 
 #endif	/* USE_NEXT_INLINE_H */
 
@@ -54,7 +54,7 @@ get_alias_set (tree *t)
       && TREE_TYPE (t).z != 3)
     return 0;
   return 1;
-}
+} // get_alias_set
 
 tree xx;
 
@@ -63,4 +63,4 @@ main()
 {
   get_alias_set (&xx);
   return 0;
-}
+} // main

gdb/testsuite/gdb.cp/step-and-next-inline.exp

@@ -67,29 +67,100 @@ proc do_test { use_header } {
     gdb_test "step" ".*" "step into get_alias_set"
     gdb_test "bt" "\\s*\\#0\\s+get_alias_set\[^\r\]*${srcfile}:.*" \
 	"not in inline 1"
+
     # It's possible that this first failure (when not using a header
     # file) is GCC's fault, though the remaining failures would best
     # be fixed by adding location views support (though it could be
     # that some easier heuristic could be figured out).  Still, it is
     # not certain that the first failure wouldn't also be fixed by
     # having location view support, so for now it is tagged as such.
-    if {[test_compiler_info gcc*] && !$use_header} {
+    set have_kfail [expr [test_compiler_info gcc*] && !$use_header]
-	setup_kfail "*-*-*" symtab/25507
+
+    set ok 1
+    gdb_test_multiple "next" "next step 1" {
+	-re -wrap "if \\(t->x != i\\)" {
+	    set ok 0
+	    send_gdb "next\n"
+	    exp_continue
+	}
+	-re -wrap ".*TREE_TYPE.* != 1" {
+	    if { $ok } {
+		pass $gdb_test_name
+	    } else {
+		if { $have_kfail } {
+		    setup_kfail "*-*-*" symtab/25507
+		}
+		fail $gdb_test_name
+	    }
+	}
     }
-    gdb_test "next" ".*TREE_TYPE.*" "next step 1"
     gdb_test "bt" "\\s*\\#0\\s+get_alias_set\[^\r\]*${srcfile}:.*" \
 	"not in inline 2"
-    gdb_test "next" ".*TREE_TYPE.*" "next step 2"
+
+    set ok 1
+    gdb_test_multiple "next" "next step 2" {
+	-re -wrap "return x;" {
+	    set ok 0
+	    send_gdb "next\n"
+	    exp_continue
+	}
+	-re -wrap ".*TREE_TYPE.* != 2" {
+	    if { $ok } {
+		pass $gdb_test_name
+	    } else {
+		if { $have_kfail } {
+		    setup_kfail "*-*-*" symtab/25507
+		}
+		fail $gdb_test_name
+	    }
+	}
+    }
     gdb_test "bt" "\\s*\\#0\\s+get_alias_set\[^\r\]*${srcfile}:.*" \
 	"not in inline 3"
-    if {[test_compiler_info gcc*] && !$use_header} {
+
-	setup_kfail "*-*-*" symtab/25507
+    set ok 1
+    gdb_test_multiple "next" "next step 3" {
+	-re -wrap "return x;" {
+	    set ok 0
+	    send_gdb "next\n"
+	    exp_continue
+	}
+	-re -wrap ".*TREE_TYPE.* != 3\\)" {
+	    if { $ok } {
+		pass $gdb_test_name
+	    } else {
+		if { $have_kfail } {
+		    setup_kfail "*-*-*" symtab/25507
+		}
+		fail $gdb_test_name
+	    }
+	}
     }
-    gdb_test "next" ".*TREE_TYPE.*" "next step 3"
     gdb_test "bt" "\\s*\\#0\\s+get_alias_set\[^\r\]*${srcfile}:.*" \
 	"not in inline 4"
-    if {!$use_header} { setup_kfail "*-*-*" symtab/25507 }
+
-    gdb_test "next" "return 0.*" "next step 4"
+    set ok 1
+    gdb_test_multiple "next" "next step 4" {
+	-re -wrap "(if \\(t != NULL|\} // get_alias_set)" {
+	    send_gdb "next\n"
+	    exp_continue
+	}
+	-re -wrap "return x;" {
+	    set ok 0
+	    send_gdb "next\n"
+	    exp_continue
+	}
+	-re -wrap "return 0.*" {
+	    if { $ok } {
+		pass $gdb_test_name
+	    } else {
+		if { $have_kfail } {
+		    setup_kfail "*-*-*" symtab/25507
+		}
+		fail $gdb_test_name
+	    }
+	}
+    }
     gdb_test "bt" \
 	"\\s*\\#0\\s+(main|get_alias_set)\[^\r\]*${srcfile}:.*" \
 	"not in inline 5"

gdb/testsuite/gdb.cp/step-and-next-inline.h

@@ -35,4 +35,4 @@ tree_check (tree *t, int i)
     abort();
   tree *x = t;
   return x;
-}
+} // tree_check