build: Fix coverage generation.

The essential change is that `tool_exec` should be in the `target` config, not
`exec`.  This alone makes the instrumentation propagate to this attribute!

testsuite/dejagnu.bzl

@@ -14,6 +14,11 @@ def _dejagnu_lib_impl(ctx):
     return [
         DefaultInfo(runfiles = runfiles),
         DejaGNULibraryInfo(),
+        coverage_common.instrumented_files_info(
+            ctx,
+            source_attributes = ["srcs"],
+            dependency_attributes = ["deps"],
+            ),
     ]
 
 dejagnu_library = rule(
@@ -62,7 +67,12 @@ def _dejagnu_test_impl(ctx):
     ])
 
     test_env = {}
-    if ctx.configuration.coverage_enabled:
+    # Are this rule's sources or any of the sources for its direct dependencies
+    # in deps instrumented?
+    if (ctx.configuration.coverage_enabled and
+        (ctx.coverage_instrumented() or
+         any([ctx.coverage_instrumented(dep) for dep in ctx.attr.deps])
+         or ctx.coverage_instrumented(ctx.attr.tool_exec))):
         # Bazel’s coverage runner
         # (https://github.com/bazelbuild/bazel/blob/6.4.0/tools/test/collect_coverage.sh)
         # needs a binary called “lcov_merge.”  Its location is passed in the
@@ -107,7 +117,7 @@ dejagnu_test = rule(
     attrs = {
         "srcs": attr.label_list(
             allow_files = [".exp"],
-            doc = "Main test file for dejagnu runtests.",
+            doc = "Test sources for dejagnu runtests.",
         ),
         "deps": attr.label_list(providers = [DejaGNULibraryInfo]),
         "data": attr.label_list(
@@ -116,7 +126,7 @@ dejagnu_test = rule(
         "tool_exec": attr.label(
             executable = True,
             doc = "Binary target under test.",
-            cfg = "exec",
+            cfg = "target",
             allow_single_file = True,
         ),
         "_runtest": attr.label(

testsuite/dejagnu_runtest_wrapper.tpl

@@ -1,7 +1,5 @@
 #/usr/bin/env bash
 
-set -x
-
 # --- begin runfiles.bash initialization v3 ---
 # Copy-pasted from the Bazel Bash runfiles library v3.
 set -uo pipefail; set +e; f=bazel_tools/tools/bash/runfiles/runfiles.bash
@@ -13,32 +11,26 @@ source "${RUNFILES_DIR:-/dev/null}/$f" 2>/dev/null || \
   { echo>&2 "ERROR: cannot find $f"; exit 1; }; f=; set -e
 # --- end runfiles.bash initialization v3 ---
 
-
-echo -n "pwd: "
-pwd
-
 runtest=$(rlocation "{runtest}")
 
 export DEJAGNULIBS="{libdir}"
 
-
 $runtest --version
 
-ls -laLR
-
 set -e
 
 cat >site.exp <<EOF
 set tool {tool}
 set srcdir {srcdir}
 set objdir `pwd`
-info exists env(COVERAGE_DIR)
 EOF
 
-cat site.exp
-
-$runtest --global_init site.exp --status --all --debug -v -v --tool {tool} --srcdir {srcdir} --outdir $TEST_UNDECLARED_OUTPUTS_DIR
-
-
-echo "post run directory"
-ls -laLR
+$runtest \
+  --global_init site.exp \
+  --status \
+  --all \
+  --debug \
+  -v -v \
+  --tool {tool} \
+  --srcdir {srcdir} \
+  --outdir $TEST_UNDECLARED_OUTPUTS_DIR \