Increased library priority for libraries specified via --library flag

arduino/libraries/librariesresolver/cpp.go

@@ -212,7 +212,8 @@ func ComputePriority(lib *libraries.Library, header, arch string) int {
 	case libraries.User:
 		priority += 3
 	case libraries.Unmanaged:
-		priority += 4
+		// Bonus for libraries specified via --libraries flags, those libraries gets the highest priority
+		priority += 10000
 	default:
 		panic(fmt.Sprintf("Invalid library location: %d", lib.Location))
 	}

docs/sketch-build-process.md

@@ -52,6 +52,8 @@ generated for the path to each library dependency and appended to the
 If multiple libraries contain a file that matches the `#include` directive, the priority is determined by applying the
 following rules, one by one in this order, until a rule determines a winner:
 
+1. A library that has been specified using the [`--library` option](commands/arduino-cli_compile.md#options) of
+   `arduino-cli compile` wins against a library in other locations
 1. A library that is architecture compatible wins against a library that is not architecture compatible (see
    [**Architecture Matching**](#architecture-matching))
 1. A library with both [library name](#library-name-priority) and [folder name](#folder-name-priority) matching the
@@ -120,8 +122,6 @@ The "folder name priority" is determined as follows (in order of highest to lowe
 
 The "location priority" is determined as follows (in order of highest to lowest priority):
 
-1. The library is specified using the [`--library` option](commands/arduino-cli_compile.md#options) of
-   `arduino-cli compile`
 1. The library is under a custom libraries path specified via the
    [`--libraries` option](commands/arduino-cli_compile.md#options) of `arduino-cli compile` (in decreasing order of
    priority when multiple custom paths are defined)

internal/integrationtest/compile_3/lib_selection_test.go

@@ -0,0 +1,68 @@
+// This file is part of arduino-cli.
+//
+// Copyright 2022 ARDUINO SA (http://www.arduino.cc/)
+//
+// This software is released under the GNU General Public License version 3,
+// which covers the main part of arduino-cli.
+// The terms of this license can be found at:
+// https://www.gnu.org/licenses/gpl-3.0.en.html
+//
+// You can be released from the requirements of the above licenses by purchasing
+// a commercial license. Buying such a license is mandatory if you want to
+// modify or otherwise use the software for commercial activities involving the
+// Arduino software without disclosing the source code of your own applications.
+// To purchase a commercial license, send an email to [email protected].
+
+package compile_test
+
+import (
+	"testing"
+
+	"github.com/arduino/arduino-cli/internal/integrationtest"
+	"github.com/arduino/go-paths-helper"
+	"github.com/stretchr/testify/require"
+	"go.bug.st/testifyjson/requirejson"
+)
+
+func TestCompileLibrarySelection(t *testing.T) {
+	// See: https://github.com/arduino/arduino-cli/issues/2106
+
+	env, cli := integrationtest.CreateArduinoCLIWithEnvironment(t)
+	defer env.CleanUp()
+
+	// Run update-index with our test index
+	_, _, err := cli.Run("core", "install", "arduino:[email protected]")
+	require.NoError(t, err)
+
+	// Prepare sketchbook and sketch
+	sketchBook, err := paths.New("testdata", "sketchbook_for_testing_lib_priorities").Abs()
+	require.NoError(t, err)
+	vars := cli.GetDefaultEnv()
+	vars["ARDUINO_DIRECTORIES_USER"] = sketchBook.String()
+
+	sketch := sketchBook.Join("SketchUsingLibraryA")
+	anotherLib := sketchBook.Join("libraries", "AnotherLibrary")
+
+	// Perform two compile:
+	// - the first should use LibraryA
+	stdout, _, err := cli.RunWithCustomEnv(vars, "compile", "-b", "arduino:avr:mega", "--format", "json", sketch.String())
+	require.NoError(t, err)
+	requirejson.Contains(t, stdout, `{
+		"builder_result" : {
+			"used_libraries" : [
+				{ "name": "LibraryA" }
+			]
+		}
+	}`)
+
+	// - the second should use AnotherLibrary (because it was forced by --library)
+	stdout, _, err = cli.RunWithCustomEnv(vars, "compile", "-b", "arduino:avr:mega", "--library", anotherLib.String(), "--format", "json", sketch.String())
+	require.NoError(t, err)
+	requirejson.Contains(t, stdout, `{
+		"builder_result" : {
+			"used_libraries" : [
+				{ "name": "AnotherLibrary" }
+			]
+		}
+	}`)
+}

internal/integrationtest/compile_3/testdata/sketchbook_for_testing_lib_priorities/SketchUsingLibraryA/SketchUsingLibraryA.ino

@@ -0,0 +1,3 @@
+#include <LibraryA.h>
+void setup() {}
+void loop() {}