From 83bb494a30a9e659a53eb757242fa0113aeae556 Mon Sep 17 00:00:00 2001 From: Rebecca Turner Date: Wed, 6 Dec 2023 12:42:53 -0800 Subject: [PATCH] Print the value in `error: cannot coerce` messages This extends the `error: cannot coerce a TYPE to a string` message to print the value that could not be coerced. This helps with debugging by making it easier to track down where the value is being produced from, especially in errors with deep or unhelpful stack traces. --- .../rl-next/print-value-in-coercion-error.md | 24 ++++++++++++++++ .../src/language/string-interpolation.md | 2 +- src/libexpr/eval.cc | 10 +++++-- src/libexpr/print-options.hh | 8 +++++- src/libexpr/print.cc | 11 +++++--- ...al-fail-bad-string-interpolation-1.err.exp | 2 +- ...al-fail-bad-string-interpolation-3.err.exp | 2 +- ...al-fail-bad-string-interpolation-4.err.exp | 2 +- tests/unit/libexpr/error_traces.cc | 28 +++++++++---------- tests/unit/libexpr/value/print.cc | 10 +++---- 10 files changed, 68 insertions(+), 31 deletions(-) create mode 100644 doc/manual/rl-next/print-value-in-coercion-error.md diff --git a/doc/manual/rl-next/print-value-in-coercion-error.md b/doc/manual/rl-next/print-value-in-coercion-error.md new file mode 100644 index 00000000000..046e4e3cf4a --- /dev/null +++ b/doc/manual/rl-next/print-value-in-coercion-error.md @@ -0,0 +1,24 @@ +--- +synopsis: Coercion errors include the failing value +issues: #561 +prs: #9754 +--- + +The `error: cannot coerce a to a string` message now includes the value +which caused the error. + +Before: + +``` + error: cannot coerce a set to a string +``` + +After: + +``` + error: cannot coerce a set to a string: { aesSupport = «thunk»; + avx2Support = «thunk»; avx512Support = «thunk»; avxSupport = «thunk»; + canExecute = «thunk»; config = «thunk»; darwinArch = «thunk»; darwinMinVersion + = «thunk»; darwinMinVersionVariable = «thunk»; darwinPlatform = «thunk»; «84 + attributes elided»} +``` diff --git a/doc/manual/src/language/string-interpolation.md b/doc/manual/src/language/string-interpolation.md index e999b287b9c..6e28d26646b 100644 --- a/doc/manual/src/language/string-interpolation.md +++ b/doc/manual/src/language/string-interpolation.md @@ -189,7 +189,7 @@ If neither is present, an error is thrown. > "${a}" > ``` > -> error: cannot coerce a set to a string +> error: cannot coerce a set to a string: { } > > at «string»:4:2: > diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc index 71e956e10bf..437a6b7bf55 100644 --- a/src/libexpr/eval.cc +++ b/src/libexpr/eval.cc @@ -2255,7 +2255,9 @@ BackedStringView EvalState::coerceToString( return std::move(*maybeString); auto i = v.attrs->find(sOutPath); if (i == v.attrs->end()) { - error("cannot coerce %1% to a string", showType(v)) + error("cannot coerce %1% to a string: %2%", + showType(v), + ValuePrinter(*this, v, errorPrintOptions)) .withTrace(pos, errorCtx) .debugThrow(); } @@ -2301,7 +2303,9 @@ BackedStringView EvalState::coerceToString( } } - error("cannot coerce %1% to a string", showType(v)) + error("cannot coerce %1% to a string: %2%", + showType(v), + ValuePrinter(*this, v, errorPrintOptions)) .withTrace(pos, errorCtx) .debugThrow(); } @@ -2661,7 +2665,7 @@ void EvalState::printStatistics() std::string ExternalValueBase::coerceToString(const Pos & pos, NixStringContext & context, bool copyMore, bool copyToStore) const { throw TypeError({ - .msg = hintfmt("cannot coerce %1% to a string", showType()) + .msg = hintfmt("cannot coerce %1% to a string: %2%", showType(), *this) }); } diff --git a/src/libexpr/print-options.hh b/src/libexpr/print-options.hh index aba2eaeae59..e03746ece44 100644 --- a/src/libexpr/print-options.hh +++ b/src/libexpr/print-options.hh @@ -36,11 +36,17 @@ struct PrintOptions */ size_t maxDepth = std::numeric_limits::max(); /** - * Maximum number of attributes in an attribute set to print. + * Maximum number of attributes in attribute sets to print. + * + * Note that this is a limit for the entire print invocation, not for each + * attribute set encountered. */ size_t maxAttrs = std::numeric_limits::max(); /** * Maximum number of list items to print. + * + * Note that this is a limit for the entire print invocation, not for each + * list encountered. */ size_t maxListItems = std::numeric_limits::max(); /** diff --git a/src/libexpr/print.cc b/src/libexpr/print.cc index dad6dc9ad09..702e4bfe8c1 100644 --- a/src/libexpr/print.cc +++ b/src/libexpr/print.cc @@ -20,7 +20,7 @@ void printElided( { if (ansiColors) output << ANSI_FAINT; - output << " «"; + output << "«"; pluralize(output, value, single, plural); output << " elided»"; if (ansiColors) @@ -37,7 +37,7 @@ printLiteralString(std::ostream & str, const std::string_view string, size_t max str << "\""; for (auto i = string.begin(); i != string.end(); ++i) { if (charsPrinted >= maxLength) { - str << "\""; + str << "\" "; printElided(str, string.length() - charsPrinted, "byte", "bytes", ansiColors); return str; } @@ -161,6 +161,8 @@ class Printer EvalState & state; PrintOptions options; std::optional seen; + size_t attrsPrinted = 0; + size_t listItemsPrinted = 0; void printRepeated() { @@ -279,7 +281,6 @@ class Printer else std::sort(sorted.begin(), sorted.end(), ImportantFirstAttrNameCmp()); - size_t attrsPrinted = 0; for (auto & i : sorted) { if (attrsPrinted >= options.maxAttrs) { printElided(sorted.size() - attrsPrinted, "attribute", "attributes"); @@ -307,7 +308,6 @@ class Printer output << "[ "; if (depth < options.maxDepth) { - size_t listItemsPrinted = 0; for (auto elem : v.listItems()) { if (listItemsPrinted >= options.maxListItems) { printElided(v.listSize() - listItemsPrinted, "item", "items"); @@ -486,6 +486,9 @@ class Printer void print(Value & v) { + attrsPrinted = 0; + listItemsPrinted = 0; + if (options.trackRepeated) { seen.emplace(); } else { diff --git a/tests/functional/lang/eval-fail-bad-string-interpolation-1.err.exp b/tests/functional/lang/eval-fail-bad-string-interpolation-1.err.exp index b461b2e02ad..5ae53034d18 100644 --- a/tests/functional/lang/eval-fail-bad-string-interpolation-1.err.exp +++ b/tests/functional/lang/eval-fail-bad-string-interpolation-1.err.exp @@ -5,4 +5,4 @@ error: | ^ 2| - error: cannot coerce a function to a string + error: cannot coerce a function to a string: «lambda @ /pwd/lang/eval-fail-bad-string-interpolation-1.nix:1:4» diff --git a/tests/functional/lang/eval-fail-bad-string-interpolation-3.err.exp b/tests/functional/lang/eval-fail-bad-string-interpolation-3.err.exp index 95f4c246004..170a3d13233 100644 --- a/tests/functional/lang/eval-fail-bad-string-interpolation-3.err.exp +++ b/tests/functional/lang/eval-fail-bad-string-interpolation-3.err.exp @@ -5,4 +5,4 @@ error: | ^ 2| - error: cannot coerce a function to a string + error: cannot coerce a function to a string: «lambda @ /pwd/lang/eval-fail-bad-string-interpolation-3.nix:1:5» diff --git a/tests/functional/lang/eval-fail-bad-string-interpolation-4.err.exp b/tests/functional/lang/eval-fail-bad-string-interpolation-4.err.exp index 4950f8ddb80..5119238d77d 100644 --- a/tests/functional/lang/eval-fail-bad-string-interpolation-4.err.exp +++ b/tests/functional/lang/eval-fail-bad-string-interpolation-4.err.exp @@ -6,4 +6,4 @@ error: | ^ 10| - error: cannot coerce a set to a string + error: cannot coerce a set to a string: { a = { a = { a = { a = "ha"; b = "ha"; c = "ha"; d = "ha"; e = "ha"; f = "ha"; g = "ha"; h = "ha"; j = "ha"; }; «4294967295 attributes elided»}; «4294967294 attributes elided»}; «4294967293 attributes elided»} diff --git a/tests/unit/libexpr/error_traces.cc b/tests/unit/libexpr/error_traces.cc index f0cad58bbda..b6fbf02fe16 100644 --- a/tests/unit/libexpr/error_traces.cc +++ b/tests/unit/libexpr/error_traces.cc @@ -295,7 +295,7 @@ namespace nix { TEST_F(ErrorTraceTest, toPath) { ASSERT_TRACE2("toPath []", TypeError, - hintfmt("cannot coerce %s to a string", "a list"), + hintfmt("cannot coerce %s to a string: %s", "a list", "[ ]"), hintfmt("while evaluating the first argument passed to builtins.toPath")); ASSERT_TRACE2("toPath \"foo\"", @@ -309,7 +309,7 @@ namespace nix { TEST_F(ErrorTraceTest, storePath) { ASSERT_TRACE2("storePath true", TypeError, - hintfmt("cannot coerce %s to a string", "a Boolean"), + hintfmt("cannot coerce %s to a string: %s", "a Boolean", ANSI_CYAN "true" ANSI_NORMAL), hintfmt("while evaluating the first argument passed to 'builtins.storePath'")); } @@ -318,7 +318,7 @@ namespace nix { TEST_F(ErrorTraceTest, pathExists) { ASSERT_TRACE2("pathExists []", TypeError, - hintfmt("cannot coerce %s to a string", "a list"), + hintfmt("cannot coerce %s to a string: %s", "a list", "[ ]"), hintfmt("while realising the context of a path")); ASSERT_TRACE2("pathExists \"zorglub\"", @@ -332,7 +332,7 @@ namespace nix { TEST_F(ErrorTraceTest, baseNameOf) { ASSERT_TRACE2("baseNameOf []", TypeError, - hintfmt("cannot coerce %s to a string", "a list"), + hintfmt("cannot coerce %s to a string: %s", "a list", "[ ]"), hintfmt("while evaluating the first argument passed to builtins.baseNameOf")); } @@ -377,7 +377,7 @@ namespace nix { TEST_F(ErrorTraceTest, filterSource) { ASSERT_TRACE2("filterSource [] []", TypeError, - hintfmt("cannot coerce %s to a string", "a list"), + hintfmt("cannot coerce %s to a string: %s", "a list", "[ ]"), hintfmt("while evaluating the second argument (the path to filter) passed to 'builtins.filterSource'")); ASSERT_TRACE2("filterSource [] \"foo\"", @@ -1038,7 +1038,7 @@ namespace nix { TEST_F(ErrorTraceTest, toString) { ASSERT_TRACE2("toString { a = 1; }", TypeError, - hintfmt("cannot coerce %s to a string", "a set"), + hintfmt("cannot coerce %s to a string: %s", "a set", "{ a = " ANSI_CYAN "1" ANSI_NORMAL "; }"), hintfmt("while evaluating the first argument passed to builtins.toString")); } @@ -1057,7 +1057,7 @@ namespace nix { ASSERT_TRACE2("substring 0 3 {}", TypeError, - hintfmt("cannot coerce %s to a string", "a set"), + hintfmt("cannot coerce %s to a string: %s", "a set", "{ }"), hintfmt("while evaluating the third argument (the string) passed to builtins.substring")); ASSERT_TRACE1("substring (-3) 3 \"sometext\"", @@ -1070,7 +1070,7 @@ namespace nix { TEST_F(ErrorTraceTest, stringLength) { ASSERT_TRACE2("stringLength {} # TODO: context is missing ???", TypeError, - hintfmt("cannot coerce %s to a string", "a set"), + hintfmt("cannot coerce %s to a string: %s", "a set", "{ }"), hintfmt("while evaluating the argument passed to builtins.stringLength")); } @@ -1143,7 +1143,7 @@ namespace nix { ASSERT_TRACE2("concatStringsSep \"foo\" [ 1 2 {} ] # TODO: coerce to string is buggy", TypeError, - hintfmt("cannot coerce %s to a string", "an integer"), + hintfmt("cannot coerce %s to a string: %s", "an integer", ANSI_CYAN "1" ANSI_NORMAL), hintfmt("while evaluating one element of the list of strings to concat passed to builtins.concatStringsSep")); } @@ -1229,12 +1229,12 @@ namespace nix { ASSERT_TRACE2("derivationStrict { name = \"foo\"; builder = 1; system = {}; }", TypeError, - hintfmt("cannot coerce %s to a string", "a set"), + hintfmt("cannot coerce %s to a string: %s", "a set", "{ }"), hintfmt("while evaluating the attribute 'system' of derivation 'foo'")); ASSERT_TRACE2("derivationStrict { name = \"foo\"; builder = 1; system = 1; outputs = {}; }", TypeError, - hintfmt("cannot coerce %s to a string", "a set"), + hintfmt("cannot coerce %s to a string: %s", "a set", "{ }"), hintfmt("while evaluating the attribute 'outputs' of derivation 'foo'")); ASSERT_TRACE2("derivationStrict { name = \"foo\"; builder = 1; system = 1; outputs = \"drv\"; }", @@ -1279,17 +1279,17 @@ namespace nix { ASSERT_TRACE2("derivationStrict { name = \"foo\"; builder = 1; system = 1; outputs = \"out\"; args = [ {} ]; }", TypeError, - hintfmt("cannot coerce %s to a string", "a set"), + hintfmt("cannot coerce %s to a string: %s", "a set", "{ }"), hintfmt("while evaluating an element of the argument list")); ASSERT_TRACE2("derivationStrict { name = \"foo\"; builder = 1; system = 1; outputs = \"out\"; args = [ \"a\" {} ]; }", TypeError, - hintfmt("cannot coerce %s to a string", "a set"), + hintfmt("cannot coerce %s to a string: %s", "a set", "{ }"), hintfmt("while evaluating an element of the argument list")); ASSERT_TRACE2("derivationStrict { name = \"foo\"; builder = 1; system = 1; outputs = \"out\"; FOO = {}; }", TypeError, - hintfmt("cannot coerce %s to a string", "a set"), + hintfmt("cannot coerce %s to a string: %s", "a set", "{ }"), hintfmt("while evaluating the attribute 'FOO' of derivation 'foo'")); } diff --git a/tests/unit/libexpr/value/print.cc b/tests/unit/libexpr/value/print.cc index 98131112e40..c4264a38dbc 100644 --- a/tests/unit/libexpr/value/print.cc +++ b/tests/unit/libexpr/value/print.cc @@ -370,7 +370,7 @@ TEST_F(ValuePrintingTests, ansiColorsStringElided) v.mkString("puppy"); test(v, - ANSI_MAGENTA "\"pup\"" ANSI_FAINT " «2 bytes elided»" ANSI_NORMAL, + ANSI_MAGENTA "\"pup\" " ANSI_FAINT "«2 bytes elided»" ANSI_NORMAL, PrintOptions { .ansiColors = true, .maxStringLength = 3 @@ -756,7 +756,7 @@ TEST_F(ValuePrintingTests, ansiColorsAttrsElided) vAttrs.mkAttrs(builder.finish()); test(vAttrs, - "{ one = " ANSI_CYAN "1" ANSI_NORMAL "; " ANSI_FAINT " «1 attribute elided»" ANSI_NORMAL "}", + "{ one = " ANSI_CYAN "1" ANSI_NORMAL "; " ANSI_FAINT "«1 attribute elided»" ANSI_NORMAL "}", PrintOptions { .ansiColors = true, .maxAttrs = 1 @@ -769,7 +769,7 @@ TEST_F(ValuePrintingTests, ansiColorsAttrsElided) vAttrs.mkAttrs(builder.finish()); test(vAttrs, - "{ one = " ANSI_CYAN "1" ANSI_NORMAL "; " ANSI_FAINT " «2 attributes elided»" ANSI_NORMAL "}", + "{ one = " ANSI_CYAN "1" ANSI_NORMAL "; " ANSI_FAINT "«2 attributes elided»" ANSI_NORMAL "}", PrintOptions { .ansiColors = true, .maxAttrs = 1 @@ -793,7 +793,7 @@ TEST_F(ValuePrintingTests, ansiColorsListElided) vList.bigList.size = 2; test(vList, - "[ " ANSI_CYAN "1" ANSI_NORMAL " " ANSI_FAINT " «1 item elided»" ANSI_NORMAL "]", + "[ " ANSI_CYAN "1" ANSI_NORMAL " " ANSI_FAINT "«1 item elided»" ANSI_NORMAL "]", PrintOptions { .ansiColors = true, .maxListItems = 1 @@ -806,7 +806,7 @@ TEST_F(ValuePrintingTests, ansiColorsListElided) vList.bigList.size = 3; test(vList, - "[ " ANSI_CYAN "1" ANSI_NORMAL " " ANSI_FAINT " «2 items elided»" ANSI_NORMAL "]", + "[ " ANSI_CYAN "1" ANSI_NORMAL " " ANSI_FAINT "«2 items elided»" ANSI_NORMAL "]", PrintOptions { .ansiColors = true, .maxListItems = 1