Use current Python version in requires-python incompatibility errors

crates/puffin-resolver/src/pubgrub/report.rs

@@ -31,6 +31,23 @@ impl ReportFormatter<PubGrubPackage, Range<Version>> for PubGrubReportFormatter<
                 format!("we are solving dependencies of {package} {version}")
             }
             External::NoVersions(package, set) => {
+                if matches!(package, PubGrubPackage::Python(_)) {
+                    // We assume there is _only_ one available Python version as Puffin only supports
+                    // resolution for a single Python version; if this is not the case for some reason
+                    // we'll just fall back to the usual verbose message in production but panic in
+                    // debug builds
+                    if let Some([version]) = self.available_versions.get(package).map(Vec::as_slice)
+                    {
+                        return format!(
+                            "{package} {version} does not satisfy {}",
+                            PackageRange::compatibility(package, set)
+                        );
+                    }
+                    debug_assert!(
+                        false,
+                        "Unexpected value for available Python versions will degrade error message"
+                    );
+                }
                 let set = self.simplify_set(set, package);
                 if set.as_ref() == &Range::full() {
                     format!("there are no versions of {package}")

crates/puffin/tests/pip_compile.rs

@@ -687,9 +687,9 @@ fn compile_python_37() -> Result<()> {
 
         ----- stderr -----
           × No solution found when resolving dependencies:
-          ╰─▶ Because there are no versions of Python that satisfy Python>=3.8
-              and black==23.10.1 depends on Python>=3.8, we can conclude that
-              black==23.10.1 cannot be used.
+          ╰─▶ Because Python 3.7.17 does not satisfy Python>=3.8 and black==23.10.1
+              depends on Python>=3.8, we can conclude that black==23.10.1 cannot be
+              used.
               And because root depends on black==23.10.1 we can conclude that the
               requirements are unsatisfiable.
         "###);

crates/puffin/tests/pip_install_scenarios.rs

@@ -2529,7 +2529,7 @@ fn requires_python_version_does_not_exist() -> Result<()> {
 
         ----- stderr -----
           × No solution found when resolving dependencies:
-          ╰─▶ Because there are no versions of Python that satisfy Python>=4.0 and a==1.0.0 depends on Python>=4.0, we can conclude that a==1.0.0 cannot be used.
+          ╰─▶ Because Python 3.7 does not satisfy Python>=4.0 and a==1.0.0 depends on Python>=4.0, we can conclude that a==1.0.0 cannot be used.
               And because root depends on a==1.0.0 we can conclude that the requirements are unsatisfiable.
         "###);
     });
@@ -2585,7 +2585,7 @@ fn requires_python_version_less_than_current() -> Result<()> {
 
         ----- stderr -----
           × No solution found when resolving dependencies:
-          ╰─▶ Because there are no versions of Python that satisfy Python<=3.8 and a==1.0.0 depends on Python<=3.8, we can conclude that a==1.0.0 cannot be used.
+          ╰─▶ Because Python 3.9 does not satisfy Python<=3.8 and a==1.0.0 depends on Python<=3.8, we can conclude that a==1.0.0 cannot be used.
               And because root depends on a==1.0.0 we can conclude that the requirements are unsatisfiable.
         "###);
     });
@@ -2641,7 +2641,7 @@ fn requires_python_version_greater_than_current() -> Result<()> {
 
         ----- stderr -----
           × No solution found when resolving dependencies:
-          ╰─▶ Because there are no versions of Python that satisfy Python>=3.10 and a==1.0.0 depends on Python>=3.10, we can conclude that a==1.0.0 cannot be used.
+          ╰─▶ Because Python 3.9 does not satisfy Python>=3.10 and a==1.0.0 depends on Python>=3.10, we can conclude that a==1.0.0 cannot be used.
               And because root depends on a==1.0.0 we can conclude that the requirements are unsatisfiable.
         "###);
     });
@@ -2846,22 +2846,22 @@ fn requires_python_version_greater_than_current_excluded() -> Result<()> {
 
         ----- stderr -----
           × No solution found when resolving dependencies:
-          ╰─▶ Because there are no versions of Python that satisfy Python>=3.10,<3.11 and there are no versions of Python that satisfy Python>=3.12, we can conclude that any of:
+          ╰─▶ Because Python 3.9 does not satisfy Python>=3.10,<3.11 and Python 3.9 does not satisfy Python>=3.12, we can conclude that any of:
                   Python>=3.10,<3.11
                   Python>=3.12
                are incompatible.
-              And because there are no versions of Python that satisfy Python>=3.11,<3.12 we can conclude that Python>=3.10 are incompatible.
+              And because Python 3.9 does not satisfy Python>=3.11,<3.12 we can conclude that Python>=3.10 are incompatible.
               And because a==2.0.0 depends on Python>=3.10 and there are no versions of a that satisfy any of:
                   a>2.0.0,<3.0.0
                   a>3.0.0,<4.0.0
                   a>4.0.0
               we can conclude that a>=2.0.0,<3.0.0 cannot be used. (1)
 
-              Because there are no versions of Python that satisfy Python>=3.11,<3.12 and there are no versions of Python that satisfy Python>=3.12, we can conclude that Python>=3.11 are incompatible.
+              Because Python 3.9 does not satisfy Python>=3.11,<3.12 and Python 3.9 does not satisfy Python>=3.12, we can conclude that Python>=3.11 are incompatible.
               And because a==3.0.0 depends on Python>=3.11 we can conclude that a==3.0.0 cannot be used.
               And because we know from (1) that a>=2.0.0,<3.0.0 cannot be used, we can conclude that a>=2.0.0,<4.0.0 cannot be used. (2)
 
-              Because there are no versions of Python that satisfy Python>=3.12 and a==4.0.0 depends on Python>=3.12, we can conclude that a==4.0.0 cannot be used.
+              Because Python 3.9 does not satisfy Python>=3.12 and a==4.0.0 depends on Python>=3.12, we can conclude that a==4.0.0 cannot be used.
               And because we know from (2) that a>=2.0.0,<4.0.0 cannot be used, we can conclude that a>=2.0.0 cannot be used.
               And because root depends on a>=2.0.0 we can conclude that the requirements are unsatisfiable.
         "###);