Merge pull request #9568 from hercules-ci/revert-9553

Revert 9553

doc/manual/rl-next/print-value-in-coercion-error.md

@@ -1,50 +0,0 @@
-synopsis: Coercion errors include the failing value
-issues: #561
-prs: #9553
-description: {
-
-The `error: cannot coerce a <TYPE> to a string` message now includes the value which caused the error.
-
-Previously, a failed string coercion produced a confusing error message if the trace didn't show where the offending value was defined:
-
-```bash
-$ nix-instantiate --eval --expr '
-let x = { a = 1; }; in
-
-"${x}"
-'
-error:
-       … while evaluating a path segment
-
-         at «string»:4:2:
-
-            3|
-            4| "${x}"
-             |  ^
-            5|
-
-       error: cannot coerce a set to a string
-```
-
-Now, the error message includes the value itself:
-
-```bash
-$ nix-instantiate --eval --expr '
-let x = { a = 1; }; in
-
-"${x}"
-'
-error:
-       … while evaluating a path segment
-
-         at «string»:4:2:
-
-            3|
-            4| "${x}"
-             |  ^
-            5|
-
-       error: cannot coerce a set to a string: { a = 1; }
-```
-
-}

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:
 >

src/libexpr/eval.cc

@@ -27,9 +27,9 @@
 #include <unistd.h>
 #include <sys/time.h>
 #include <sys/resource.h>
+#include <iostream>
 #include <fstream>
 #include <functional>
-#include <sstream>
 
 #include <sys/resource.h>
 #include <nlohmann/json.hpp>
@@ -2230,7 +2230,7 @@ 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: %2%", showType(v), printValue(*this, v))
+            error("cannot coerce %1% to a string", showType(v))
                 .withTrace(pos, errorCtx)
                 .debugThrow<TypeError>();
         }
@@ -2276,7 +2276,7 @@ BackedStringView EvalState::coerceToString(
         }
     }
 
-    error("cannot coerce %1% to a string: %2%", showType(v), printValue(*this, v))
+    error("cannot coerce %1% to a string", showType(v))
         .withTrace(pos, errorCtx)
         .debugThrow<TypeError>();
 }
@@ -2635,10 +2635,8 @@ void EvalState::printStatistics()
 
 std::string ExternalValueBase::coerceToString(const Pos & pos, NixStringContext & context, bool copyMore, bool copyToStore) const
 {
-    std::stringstream printed;
-    print(printed);
     throw TypeError({
-        .msg = hintfmt("cannot coerce %1% to a string: %2%", showType(), printed.str())
+        .msg = hintfmt("cannot coerce %1% to a string", showType())
     });
 }
 

tests/functional/lang/eval-fail-bad-string-interpolation-1.err.exp

@@ -7,4 +7,4 @@ error:
              |  ^
             2|
 
-       error: cannot coerce a function to a string: <LAMBDA>
+       error: cannot coerce a function to a string

tests/functional/lang/eval-fail-bad-string-interpolation-3.err.exp

@@ -7,4 +7,4 @@ error:
              |   ^
             2|
 
-       error: cannot coerce a function to a string: <LAMBDA>
+       error: cannot coerce a function to a string

tests/functional/lang/eval-fail-bad-string-interpolation-4.err.exp

@@ -0,0 +1,11 @@
+error:
+       … while evaluating a path segment
+
+         at /pwd/lang/eval-fail-bad-string-interpolation-4.nix:9:3:
+
+            8| # The error message should not be too long.
+            9| ''${pkgs}''
+             |   ^
+           10|
+
+       error: cannot coerce a set to a string

tests/functional/lang/eval-fail-bad-string-interpolation-4.nix

@@ -0,0 +1,9 @@
+let
+  # Basically a "billion laughs" attack, but toned down to simulated `pkgs`.
+  ha = x: y: { a = x y; b = x y; c = x y; d = x y; e = x y; f = x y; g = x y; h = x y; j = x y; };
+  has = ha (ha (ha (ha (x: x)))) "ha";
+  # A large structure that has already been evaluated.
+  pkgs = builtins.deepSeq has has;
+in
+# The error message should not be too long.
+''${pkgs}''

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: %s", "a list", "[ ]"),
+                      hintfmt("cannot coerce %s to a string", "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: %s", "a Boolean", "true"),
+                      hintfmt("cannot coerce %s to a string", "a Boolean"),
                       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: %s", "a list", "[ ]"),
+                      hintfmt("cannot coerce %s to a string", "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: %s", "a list", "[ ]"),
+                      hintfmt("cannot coerce %s to a string", "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: %s", "a list", "[ ]"),
+                      hintfmt("cannot coerce %s to a string", "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: %s", "a set", "{ a = 1; }"),
+                      hintfmt("cannot coerce %s to a string", "a set"),
                       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: %s", "a set", "{ }"),
+                      hintfmt("cannot coerce %s to a string", "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: %s", "a set", "{ }"),
+                      hintfmt("cannot coerce %s to a string", "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: %s", "an integer", "1"),
+                      hintfmt("cannot coerce %s to a string", "an integer"),
                       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: %s", "a set", "{ }"),
+                      hintfmt("cannot coerce %s to a string", "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: %s", "a set", "{ }"),
+                      hintfmt("cannot coerce %s to a string", "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: %s", "a set", "{ }"),
+                      hintfmt("cannot coerce %s to a string", "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: %s", "a set", "{ }"),
+                      hintfmt("cannot coerce %s to a string", "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: %s", "a set", "{ }"),
+                      hintfmt("cannot coerce %s to a string", "a set"),
                       hintfmt("while evaluating the attribute 'FOO' of derivation 'foo'"));
 
     }