testsuite: Add support for dg-output-file directive

The COBOL tests has many tests which just dump emit lots of output
to stdout and want to compare it against expected output.
We have the dg-output directive, but if one needs more than dozens
of lines in the output, adding hundreds of dg-output directives to
each source uses too much memory and is harder to maintain.

The following patch offers an alternative, dg-output-file
directive where one can supply a text file with expected output
(no regexp matching in that case, just exact output, except that it
handles different line ending styles (for the expected file
using tcl gets, for the actual output skips over \n, \r\n or \r).
And a newline at the end of the whole output is optional (in the actual
output, because I think some boards get it eaten).

Also tested with addition or subtraction of some characters from the
expected output files and saw FAILs with appropriate messages.

2025-03-18  Jakub Jelinek  <jakub@redhat.com>

	* doc/sourcebuild.texi (dg-output-file): Document.

	* lib/gcc-dg.exp (${tool}-load): If output-file is set, compare
	combined output against content of the [lindex ${output-file} 1]
	file.
	(dg-output-file): New directive.
	* lib/dg-test-cleanup.exp (cleanup-after-saved-dg-test): Clear
	output-file variable.
	* gcc.dg/dg-output-file-1.c: New test.
	* gcc.dg/dg-output-file-1-lp64.txt: New test.
	* gcc.dg/dg-output-file-1-ilp32.txt: New test.

6 files changed, 126 insertions, 0 deletions

diff --git a/gcc/doc/sourcebuild.texi b/gcc/doc/sourcebuild.texi
index 1142039..84fd273 100644
--- a/gcc/doc/sourcebuild.texi
+++ b/gcc/doc/sourcebuild.texi
@@ -1315,6 +1315,10 @@ Prune messages matching @var{regexp} from the test output.
 @item @{ dg-output @var{regexp} [@{ target/xfail @var{selector} @}] @}
 This DejaGnu directive compares @var{regexp} to the combined output
 that the test executable writes to @file{stdout} and @file{stderr}.
+
+@item @{ dg-output-file @var{file} [@{ target/xfail @var{selector} @}] @}
+Compares the content of @var{file} against the combined output that the
+test executable writes to @file{stdout} and @file{stderr}.
 @end table
 
 @subsubsection Specify environment variables for a test
diff --git a/gcc/testsuite/gcc.dg/dg-output-file-1-ilp32.txt b/gcc/testsuite/gcc.dg/dg-output-file-1-ilp32.txt
new file mode 100644
index 0000000..0255ead
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/dg-output-file-1-ilp32.txt
@@ -0,0 +1,3 @@
+This is a test output for ilp32 target
+to verify
+dg-output-file directive
diff --git a/gcc/testsuite/gcc.dg/dg-output-file-1-lp64.txt b/gcc/testsuite/gcc.dg/dg-output-file-1-lp64.txt
new file mode 100644
index 0000000..e6d9c8e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/dg-output-file-1-lp64.txt
@@ -0,0 +1,3 @@
+This is a test output for lp64 target
+to verify
+dg-output-file directive
diff --git a/gcc/testsuite/gcc.dg/dg-output-file-1.c b/gcc/testsuite/gcc.dg/dg-output-file-1.c
new file mode 100644
index 0000000..5ad632c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/dg-output-file-1.c
@@ -0,0 +1,13 @@
+/* { dg-do run { target { lp64 || ilp32 } } } */
+/* { dg-options "-O2" } */
+/* { dg-output-file "dg-output-file-1-lp64.txt" { target lp64 } } */
+/* { dg-output-file "dg-output-file-1-ilp32.txt" { target ilp32 } } */
+
+int
+main ()
+{
+  __builtin_printf ("This is a test output for %s target\n"
+		    "to verify\n"
+		    "dg-output-file directive\n",
+		    __SIZEOF_LONG__ * __CHAR_BIT__ == 64 ? "lp64" : "ilp32");
+}
diff --git a/gcc/testsuite/lib/dg-test-cleanup.exp b/gcc/testsuite/lib/dg-test-cleanup.exp
index 27b1eb3..308ee00 100644
--- a/gcc/testsuite/lib/dg-test-cleanup.exp
+++ b/gcc/testsuite/lib/dg-test-cleanup.exp
@@ -45,6 +45,7 @@ if { [info procs saved-dg-test] == [list] } {
 	global multiline_expected_outputs
 	global freeform_regexps
 	global save_linenr_varnames
+	global output-file
 
 	set additional_files ""
 	set additional_sources ""
@@ -70,6 +71,9 @@ if { [info procs saved-dg-test] == [list] } {
 	if [info exists testname_with_flags] {
 	    unset testname_with_flags
 	}
+	if [info exists output-file] {
+	    unset output-file
+	}
 	set nn_line_numbers_enabled 0
 	set multiline_expected_outputs []
 	set freeform_regexps []
diff --git a/gcc/testsuite/lib/gcc-dg.exp b/gcc/testsuite/lib/gcc-dg.exp
index f5ad424..eadc1cd 100644
--- a/gcc/testsuite/lib/gcc-dg.exp
+++ b/gcc/testsuite/lib/gcc-dg.exp
@@ -473,6 +473,7 @@ if { [info procs ${tool}_load] != [list] \
 	global tool
 	global shouldfail
 	global set_target_env_var
+	global output-file
 
 	set saved_target_env_var [list]
 	if { [info exists set_target_env_var] \
@@ -497,6 +498,75 @@ if { [info procs ${tool}_load] != [list] \
 	}
 
 	set result [list [lindex $result 0] [prune_file_path [lindex $result 1]]]
+	if { [info exists output-file] && [lindex $result 0] eq "pass" } {
+	    if { [lindex ${output-file} 0] eq "F" } {
+		setup_xfail "*-*-*"
+	    }
+	    set output [lindex $result 1]
+	    set idx 0
+	    set linenum 1
+	    set outfile [open [lindex ${output-file} 1]]
+	    set do_fail 0
+	    set name [file tail [lindex ${output-file} 1]]
+	    verbose "output-file args is $args program is $program" 1
+	    while { [gets $outfile line] >= 0 } {
+		if { $linenum != 1 } {
+		    set c [string index $output $idx]
+		    if { $c eq "\n" } {
+			set idx [expr $idx + 1]
+		    } elseif { $c eq "\r" } {
+			set idx [expr $idx + 1]
+			set c [string index $output $idx]
+			if { $c eq "\n" } {
+			    set idx [expr $idx + 1]
+			}
+		    } else {
+			set do_fail 1
+			fail "$name output file test"
+			send_log "Unexpected character $c on line [expr $linenum - 1] where new-line expected\n"
+			verbose "Failed test for output line [expr $linenum - 1]" 3
+			break
+		    }
+		}
+		set len [string length $line]
+		set output_line [string range $output $idx [expr $idx + $len - 1]]
+		if { $line ne $output_line } {
+		    set do_fail 1
+		    fail "$name output file test"
+		    send_log "Output line $linenum was:\n$output_line\nShould match (from [lindex ${output-file} 1]):\n$line\n"
+		    verbose "Failed test for output line $linenum $line" 3
+		    break
+		}
+		set idx [expr $idx + $len]
+		incr linenum
+	    }
+	    close $outfile
+	    if { $do_fail == 0 } {
+		set c [string index $output $idx]
+		if { $c eq "\n" } {
+		    set idx [expr $idx + 1]
+		} elseif { $c eq "\r" } {
+		    set idx [expr $idx + 1]
+		    set c [string index $output $idx]
+		    if { $c eq "\n" } {
+			set idx [expr $idx + 1]
+		    }
+		} else {
+		    incr linenum -1
+		}
+		set c [string index $output $idx]
+		if { $c ne "" } {
+		    fail "$name output file test"
+		    send_log "Unexpected character $c on line $linenum where and of output expected\n"
+		    verbose "Failed test for output line $linenum" 3
+		    break
+		} else {
+		    pass "$name output file test"
+		    verbose "Passed test for output file [lindex ${output-file} 1]" 3
+		}
+	    }
+	    unset output
+	}
 	return $result
     }
 }
@@ -575,6 +645,35 @@ proc restore-compiler-env-var { } {
     }
 }
 
+# Indicate expected program output in a file.
+#
+proc dg-output-file { args } {
+    global output-file
+    global srcdir subdir
+
+    if { [llength $args] > 3 } {
+	error "[lindex $args 0]: too many arguments"
+    }
+
+    # Allow target dependent output.
+
+    if { ![info exists output-file] } {
+	set output-file "P"
+    }
+    set expected [lindex ${output-file} 0]
+    if { [llength $args] >= 3 } {
+	switch -- [dg-process-target [lindex $args 2]] {
+	    "N" { return }
+	    "S" { }
+	    "F" { set expected "F" }
+	    # Don't override a previous xfail.
+	    "P" { }
+	}
+    }
+
+    set output-file [list $expected $srcdir/$subdir/[lindex $args 1]]
+}
+
 # Utility routines.
 
 #