gdb/testsuite: extend special '^' handling to gdb_test_multiple

The commit:

  commit 08ec06d644
  Date:   Wed Mar 29 10:41:07 2023 +0100

      gdb/testsuite: special case '^' in gdb_test pattern

Added some special handling of '^' to gdb_test -- a leading '^' will
cause the command regexp to automatically be included in the expected
output pattern.

It was pointed out that the '-wrap' flag of gdb_test_multiple is
supposed to work in the same way as gdb_test, and that the recent
changes for '^' had not been replicated for gdb_test_multiple.  This
patch addresses this issue.

So, after this commit, the following two constructs should have the
same meaning:

  gdb_test "command" "^output" "test name"

  gdb_test_multiple "command" "test name" {
    -re -wrap "^output" {
      pass $gdb_test_name
    }
  }

In both cases the '^' will case gdb.exp to inject a regexp that
matches 'command' after the '^' and before the 'output', this is in
addition to adding the $gdb_prompt pattern after 'output' in the
normal way.

The special '^' handling is only applied when '-wrap' is used, as this
is the only mode that aims to mimic gdb_test.

While working on this patch I realised that I could actually improve
the logic for the special '^' handling in the case where the expected
output pattern is empty.  I replicated these updates for both gdb_test
and gdb_test_multiple in order to keep these two paths in sync.

There were a small number of tests that needed adjustment after this
change, mostly just removing command regexps that are now added
automatically, but the gdb.base/settings.exp case was a little weird
as it turns out trying to match a single blank line is probably harder
now than it used to be -- still, I suspect this is a pretty rare case,
so I think the benefits (improved anchoring) outweigh this small
downside (IMHO).

gdb/testsuite/gdb.base/bitshift.exp

@@ -24,19 +24,17 @@ clean_restart
 # expected error.  If WARNING_OR_ERROR is empty, it is expected that
 # GDB prints no text other than the print result.
 proc test_shift {lang cmd result_re {warning_or_error ""}} {
-    set cmd_re [string_to_regexp $cmd]
-
     if {$lang == "go"} {
 	if {$warning_or_error != ""} {
 	    set error_re "[string_to_regexp $warning_or_error]"
 	    gdb_test_multiple $cmd "" {
-		-re -wrap "^$cmd_re\r\n$error_re" {
+		-re -wrap "^$error_re" {
 		    pass $gdb_test_name
 		}
 	    }
 	} else {
 	    gdb_test_multiple $cmd "" {
-		-re -wrap "^$cmd_re\r\n\\$$::decimal$result_re" {
+		-re -wrap "^\\$$::decimal$result_re" {
 		    pass $gdb_test_name
 		}
 	    }
@@ -49,7 +47,7 @@ proc test_shift {lang cmd result_re {warning_or_error ""}} {
 	}
 
 	gdb_test_multiple $cmd "" {
-	    -re -wrap "^$cmd_re\r\n$warning_re\\$$::decimal$result_re" {
+	    -re -wrap "^$warning_re\\$$::decimal$result_re" {
 		pass $gdb_test_name
 	    }
 	}

gdb/testsuite/gdb.base/maint-print-frame-id.exp

@@ -33,10 +33,6 @@ proc get_frame_id { level } {
     set id "**unknown**"
 
     gdb_test_multiple "maint print frame-id ${level}" "" {
-	-re "^maint print frame-id\[^\r\n\]+\r\n" {
-	    exp_continue
-	}
-
 	-wrap -re "^frame-id for frame #\[0-9\]+: (\[^\r\n\]+)" {
 	    set id $expect_out(1,string)
 	    pass $gdb_test_name

gdb/testsuite/gdb.base/settings.exp

@@ -542,7 +542,7 @@ proc test-string {variant} {
     if {$variant != "filename"} {
 	# This odd expected output here is because we expect GDB to
 	# emit a single blank line as a result of this command.
-	gdb_test "$show_cmd" "^" "$show_cmd: show default"
+	gdb_test -nonl "$show_cmd" "^\r\n" "$show_cmd: show default"
     } else {
 	gdb_test "$show_cmd" "/foo/bar" "$show_cmd: show default"
     }
@@ -574,7 +574,7 @@ proc test-string {variant} {
 	    gdb_test_no_output "$set_cmd"
 	    # This odd expected output here is because we expect GDB to
 	    # emit a single blank line as a result of this command.
-	    gdb_test "$show_cmd" "^" "$show_cmd: empty second time"
+	    gdb_test -nonl "$show_cmd" "^\r\n" "$show_cmd: empty second time"
 	}
     }
 

gdb/testsuite/gdb.base/wrap-line.exp

@@ -57,8 +57,7 @@ proc get_screen_width { } {
     set cmd "maint info screen"
     set re \
 	[multi_line \
-	     ^$cmd \
+	     ^$re1 \
-	     $re1 \
 	     $re2 \
 	     "(?:$re3" \
 	     ")?$re4" \

gdb/testsuite/gdb.dwarf2/gdb-index-nodebug.exp

@@ -49,7 +49,7 @@ gdb_test_multiple $cmd "try to save gdb index" {
     -re -wrap $no_debug_re {
 	pass $gdb_test_name
     }
-    -re -wrap "^$cmd" {
+    -re -wrap "^" {
 	pass $gdb_test_name
     }
 }

gdb/testsuite/gdb.tui/wrap-line.exp

@@ -80,8 +80,7 @@ proc test_wrap_cli_tui { auto_detected_width } {
     set cmd "maint info screen"
     set re \
 	[multi_line \
-	     "^$cmd" \
+	     "^$re1" \
-	     $re1 \
 	     $re2 \
 	    ".*"]
     gdb_test_multiple $cmd "" {

gdb/testsuite/lib/gdb.exp

@@ -980,6 +980,8 @@ proc fill_in_default_prompt {prompt_regexp with_anchor} {
 #           pass $gdb_test_name
 #       }
 #   }
+# The special handling of '^' that is available in gdb_test is also
+# supported in gdb_test_multiple when -wrap is used.
 #
 # In EXPECT_ARGUMENTS, a pattern flag -early can be used.  It makes sure the
 # pattern is inserted before any implicit pattern added by gdb_test_multiple.
@@ -1125,6 +1127,19 @@ proc gdb_test_multiple { command message args } {
 	set expecting_action 1
 	if { $wrap_pattern } {
 	    # Wrap subst_item as is done for the gdb_test PATTERN argument.
+	    if {[string range $subst_item 0 0] eq "^"} {
+		if {$command ne ""} {
+		    set command_regex [string_to_regexp $command]
+		    set subst_item [string range $subst_item 1 end]
+		    if {[string length "$subst_item"] > 0} {
+			# We have an output pattern (other than the '^'),
+			# add a newline at the start, this will eventually
+			# sit between the command and the output pattern.
+			set subst_item "\r\n${subst_item}"
+		    }
+		    set subst_item "^${command_regex}${subst_item}"
+		}
+	    }
 	    lappend $current_list \
 		"(?:$subst_item)\r\n$prompt_regexp"
 	    set wrap_pattern 0
@@ -1465,10 +1480,16 @@ proc gdb_test { args } {
     # additional pattern that matches the command immediately after
     # the '^'.
     if {[string range $pattern 0 0] eq "^"} {
-	set command_regex [string_to_regexp $command]
+	if {$command ne ""} {
-	set pattern [string range $pattern 1 end]
+	    set command_regex [string_to_regexp $command]
-	if {$command_regex ne ""} {
+	    set pattern [string range $pattern 1 end]
-	    set pattern "^${command_regex}\r\n$pattern"
+	    if {[string length "$pattern"] > 0} {
+		# We have an output pattern (other than the '^'), add a
+		# newline at the start, this will eventually sit between the
+		# command and the output pattern.
+		set pattern "\r\n$pattern"
+	    }
+	    set pattern "^${command_regex}${pattern}"
 	}
     }
 
@@ -6174,9 +6195,8 @@ proc with_set { var val body } {
 	perror "Did not manage to set $var"
     } else {
 	# Set var.
-	set cmd "set $var $val"
+	gdb_test_multiple "set $var $val" "" {
-	gdb_test_multiple $cmd "" {
+	    -re -wrap "^" {
-	    -re -wrap "^$cmd" {
 	    }
 	    -re -wrap " is set to \"?$val\"?\\." {
 	    }
@@ -6187,9 +6207,8 @@ proc with_set { var val body } {
 
     # Restore saved setting.
     if { $save != "" } {
-	set cmd "set $var $save"
+	gdb_test_multiple "set $var $save" "" {
-	gdb_test_multiple $cmd "" {
+	    -re -wrap "^" {
-	    -re -wrap "^$cmd" {
 	    }
 	    -re -wrap "is set to \"?$save\"?( \\(\[^)\]*\\))?\\." {
 	    }
@@ -7753,7 +7772,7 @@ proc get_valueof { fmt exp default {test ""} } {
 
     set val ${default}
     gdb_test_multiple "print${fmt} ${exp}" "$test" {
-	-re "\\$\[0-9\]* = (\[^\r\n\]*)\r\n$gdb_prompt $" {
+	-re -wrap "^\\$\[0-9\]* = (\[^\r\n\]*)" {
 	    set val $expect_out(1,string)
 	    pass "$test"
 	}
@@ -7802,7 +7821,7 @@ proc get_integer_valueof { exp default {test ""} } {
 
     set val ${default}
     gdb_test_multiple "print /d ${exp}" "$test" {
-	-re "\\$\[0-9\]* = (\[-\]*\[0-9\]*).*$gdb_prompt $" {
+	-re -wrap "^\\$\[0-9\]* = (\[-\]*\[0-9\]*).*" {
 	    set val $expect_out(1,string)
 	    pass "$test"
 	}