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Allow TemplateDict#map_each callback to return a list of strings (b…
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…azelbuild#17306)

Returning a list of strings is needed to get correct `uniquify` semantics when a value may expand to multiple strings.

Work towards bazelbuild#1920

Closes bazelbuild#17008.

PiperOrigin-RevId: 495868960
Change-Id: I1f0ec560fd783846e916a07bb524dd2179f7c535

Co-authored-by: Fabian Meumertzheim <[email protected]>
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@ShreeM01 @fmeum
ShreeM01 and fmeum authored Jan 26, 2023
1 parent 5a7eca2 commit baf97c0
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Showing 3 changed files with 134 additions and 8 deletions.
18 changes: 15 additions & 3 deletions src/main/java/com/google/devtools/build/lib/analysis/starlark/TemplateDict.java
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@
import java.util.List;
import net.starlark.java.eval.EvalException;
import net.starlark.java.eval.Mutability;
import net.starlark.java.eval.Sequence;
import net.starlark.java.eval.Starlark;
import net.starlark.java.eval.StarlarkCallable;
import net.starlark.java.eval.StarlarkFunction;
Expand Down Expand Up @@ -121,11 +122,22 @@ public String getValue() throws EvalException {
/*kwargs=*/ ImmutableMap.of());
if (ret instanceof String) {
parts.add((String) ret);
} else if (ret instanceof Sequence) {
for (Object v : ((Sequence) ret)) {
if (!(v instanceof String)) {
throw Starlark.errorf(
"Function provided to map_each must return string, None, or list of strings,"
+ " but returned list containing element '%s' of type %s for key '%s' and"
+ " value: %s",
v, Starlark.type(v), getKey(), val);
}
parts.add((String) v);
}
} else if (ret != Starlark.NONE) {
throw Starlark.errorf(
"Function provided to map_each must return a String or None, but returned type "
+ "%s for key '%s' and value: %s",
Starlark.type(ret), getKey(), Starlark.repr(val));
"Function provided to map_each must return string, None, or list of strings, but "
+ "returned type %s for key '%s' and value: %s",
Starlark.type(ret), getKey(), val);
}
} catch (InterruptedException e) {
// Report the error to the user, but the stack trace is not of use to them
Expand Down
6 changes: 3 additions & 3 deletions src/main/java/com/google/devtools/build/lib/starlarkbuildapi/TemplateDictApi.java
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Original file line number Diff line number Diff line change
Expand Up @@ -70,9 +70,9 @@ public interface TemplateDictApi extends StarlarkValue {
named = true,
positional = false,
doc =
"A Starlark function accepting a single argument and returning either a String or "
+ "<code>None</code>. This function is applied to each item of the depset "
+ "specified in the <code>values</code> parameter"),
"A Starlark function accepting a single argument and returning either a string, "
+ "<code>None</code>, or a list of strings. This function is applied to each "
+ "item of the depset specified in the <code>values</code> parameter"),
@Param(
name = "uniquify",
named = true,
Expand Down
118 changes: 116 additions & 2 deletions src/test/java/com/google/devtools/build/lib/starlark/StarlarkRuleContextTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -3740,6 +3740,68 @@ public void testTemplateExpansionComputedSubstitutionWithUniquify() throws Excep
assertThat(substitutionsUnchecked).isEqualTo(ImmutableMap.of("exts", "txt%%log%%exe%%sh"));
}

@Test
public void testTemplateExpansionComputedSubstitutionWithUniquifyAndListMapEach()
throws Exception {
setBuildLanguageOptions("--experimental_lazy_template_expansion");
scratch.file(
"test/rules.bzl",
"def _artifact_to_extension(file):",
" if file.extension == 'sh':",
" return [file.extension]",
" return [file.extension, '.' + file.extension]",
"",
"def _undertest_impl(ctx):",
" template_dict = ctx.actions.template_dict()",
" template_dict.add_joined('exts', depset(ctx.files.srcs),",
" map_each = _artifact_to_extension,",
" uniquify = True,",
" join_with = '%%',",
" )",
" ctx.actions.expand_template(output=ctx.outputs.out,",
" template=ctx.file.template,",
" computed_substitutions=template_dict,",
" )",
"undertest_rule = rule(",
" implementation = _undertest_impl,",
" outputs = {'out': '%{name}.txt'},",
" attrs = {'template': attr.label(allow_single_file=True),",
" 'srcs':attr.label_list(allow_files=True)",
" },",
" _skylark_testable = True,",
")",
testingRuleDefinition);
scratch.file("test/template.txt", "exts", "exts");
scratch.file(
"test/BUILD",
"load(':rules.bzl', 'undertest_rule', 'testing_rule')",
"undertest_rule(",
" name = 'undertest',",
" template = ':template.txt',",
" srcs = ['foo.txt', 'bar.log', 'baz.txt', 'bak.exe', 'far.sh', 'boo.sh'],",
")",
"testing_rule(",
" name = 'testing',",
" dep = ':undertest',",
")");
StarlarkRuleContext ruleContext = createRuleContext("//test:testing");
setRuleContext(ruleContext);
ev.update("file", ev.eval("ruleContext.attr.dep.files.to_list()[0]"));
ev.update("action", ev.eval("ruleContext.attr.dep[Actions].by_file[file]"));

assertThat(ev.eval("type(action)")).isEqualTo("Action");

Object contentUnchecked = ev.eval("action.content");
assertThat(contentUnchecked).isInstanceOf(String.class);
assertThat(contentUnchecked)
.isEqualTo("txt%%.txt%%log%%.log%%exe%%.exe%%sh\ntxt%%.txt%%log%%.log%%exe%%.exe%%sh\n");

Object substitutionsUnchecked = ev.eval("action.substitutions");
assertThat(substitutionsUnchecked).isInstanceOf(Dict.class);
assertThat(substitutionsUnchecked)
.isEqualTo(ImmutableMap.of("exts", "txt%%.txt%%log%%.log%%exe%%.exe%%sh"));
}

@Test
public void testTemplateExpansionComputedSubstitutionDuplicateKeys() throws Exception {
setBuildLanguageOptions("--experimental_lazy_template_expansion");
Expand Down Expand Up @@ -3912,8 +3974,60 @@ public void testTemplateExpansionComputedSubstitutionMapEachBadReturnType() thro
assertThat(evalException)
.hasMessageThat()
.isEqualTo(
"Function provided to map_each must return a String or None, but returned "
+ "type Label for key '%files%' and value: <source file test/template.txt>");
"Function provided to map_each must return string, None, or list of strings, "
+ "but returned type Label for key '%files%' and value: "
+ "File:[/workspace[source]]test/template.txt");
}

@Test
public void testTemplateExpansionComputedSubstitutionMapEachBadListReturnType() throws Exception {
setBuildLanguageOptions("--experimental_lazy_template_expansion");
scratch.file(
"test/rules.bzl",
"def file_to_owner_label(file):",
" return [file.owner]",
"",
"def _undertest_impl(ctx):",
" template_dict = ctx.actions.template_dict()",
" template_dict.add_joined('%files%', depset(ctx.files.template),",
" map_each = file_to_owner_label,",
" join_with = '')",
" ctx.actions.expand_template(output=ctx.outputs.out,",
" template=ctx.file.template,",
" computed_substitutions=template_dict,",
" )",
"undertest_rule = rule(",
" implementation = _undertest_impl,",
" outputs = {'out': '%{name}.txt'},",
" attrs = {'template': attr.label(allow_single_file=True),},",
" _skylark_testable = True,",
")",
testingRuleDefinition);
scratch.file("test/template.txt");
scratch.file(
"test/BUILD",
"load(':rules.bzl', 'undertest_rule', 'testing_rule')",
"undertest_rule(",
" name = 'undertest',",
" template = ':template.txt',",
")",
"testing_rule(",
" name = 'testing',",
" dep = ':undertest',",
")");
StarlarkRuleContext ruleContext = createRuleContext("//test:testing");
setRuleContext(ruleContext);
ev.update("file", ev.eval("ruleContext.attr.dep.files.to_list()[0]"));
ev.update("action", ev.eval("ruleContext.attr.dep[Actions].by_file[file]"));

EvalException evalException =
assertThrows(EvalException.class, () -> ev.eval("action.content"));
assertThat(evalException)
.hasMessageThat()
.isEqualTo(
"Function provided to map_each must return string, None, or list of strings, "
+ "but returned list containing element '//test:template.txt' of type Label for "
+ "key '%files%' and value: File:[/workspace[source]]test/template.txt");
}

@Test
Expand Down

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