test(format): pin the canonical rendering of the flags operand

Assisted-by: GLM 5.3 Flash

format/flaglist_test.go

@@ -0,0 +1,108 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: BSD-3-Clause
+
+package format
+
+import (
+	"testing"
+
+	"sourcedock.dev/petrbalvin/gasm-sdk/ast"
+	"sourcedock.dev/petrbalvin/gasm-sdk/parser"
+)
+
+// TestFlagListCanonical pins the canonical rendering of the TEXT and GLOBL
+// flags operand: the names stay glued to their '|' separators, the operands
+// take one space after each comma, and the spelling survives whatever
+// layout it arrives in.  Every shape mixes its flags with a frame size,
+// which is where the operand boundaries live.
+func TestFlagListCanonical(t *testing.T) {
+	for _, c := range []struct{ in, want string }{
+		{"TEXT ·f(SB),NOSPLIT|NOFRAME,$0-16\n\tRET\n", "TEXT ·f(SB), NOSPLIT|NOFRAME, $0-16\n\tRET\n"},
+		{"TEXT ·f(SB) , NOSPLIT|NOFRAME , $0-16\n\tRET\n", "TEXT ·f(SB), NOSPLIT|NOFRAME, $0-16\n\tRET\n"},
+		{"TEXT ·f(SB), NOSPLIT|NOFRAME|TOPFRAME, $0\n\tRET\n", "TEXT ·f(SB), NOSPLIT|NOFRAME|TOPFRAME, $0\n\tRET\n"},
+		{"TEXT ·f(SB), 2|4, $4096-0\n\tRET\n", "TEXT ·f(SB), 2|4, $4096-0\n\tRET\n"},
+		{"TEXT ·f(SB), (NOSPLIT|NOFRAME), $0-8\n\tRET\n", "TEXT ·f(SB), (NOSPLIT|NOFRAME), $0-8\n\tRET\n"},
+		{"TEXT ·foo<ABIInternal>(SB), NOSPLIT, $-0-24\n\tRET\n", "TEXT ·foo<ABIInternal>(SB), NOSPLIT, $-0-24\n\tRET\n"},
+		{"GLOBL ·mask(SB),RODATA|NOPTR,$8\n", "GLOBL ·mask(SB), RODATA|NOPTR, $8\n"},
+		{"GLOBL ·mask(SB), 10, $8\n", "GLOBL ·mask(SB), 10, $8\n"},
+	} {
+		got := Source(c.in)
+		if got != c.want {
+			t.Errorf("formatting %q:\n got  %q\n want %q", c.in, got, c.want)
+			continue
+		}
+		// The standing invariants over the rendered line: the output is its
+		// own canonical form, and formatting changed layout, never tokens.
+		if again := Source(got); again != got {
+			t.Errorf("not idempotent for %q:\n%q", c.in, again)
+		}
+		if in, out := tokenView(c.in), tokenView(got); !sameView(in, out) {
+			t.Errorf("formatting %q changed the token stream:\ninput:  %v\noutput: %v",
+				c.in, viewString(in), viewString(out))
+		}
+	}
+}
+
+// TestFlagListFormatRoundTrip covers the parser's side of the same shapes:
+// a header that parses cleanly still parses cleanly after formatting, and
+// the flags value and canonical names survive the pass unchanged.
+func TestFlagListFormatRoundTrip(t *testing.T) {
+	for _, src := range []string{
+		"TEXT ·f(SB),NOSPLIT|NOFRAME,$0-16\n\tRET\n",
+		"TEXT ·f(SB), 2|4, $4096-0\n\tRET\n",
+		"TEXT ·f(SB), (NOSPLIT|NOFRAME), $0-8\n\tRET\n",
+		"GLOBL ·mask(SB),RODATA|NOPTR,$8\n",
+	} {
+		before, errs := parser.Parse("in.s", src)
+		if len(errs) > 0 {
+			t.Fatalf("parse %q: %v", src, errs)
+		}
+		after, errs := parser.Parse("in.s", Source(src))
+		if len(errs) > 0 {
+			t.Fatalf("formatted %q no longer parses: %v", src, errs)
+		}
+		beforeD, afterD := firstFlaggedDecl(before), firstFlaggedDecl(after)
+		if beforeD == nil || afterD == nil {
+			t.Fatalf("%q: a TEXT or GLOBL declaration was lost by formatting", src)
+		}
+		beforeFlags, beforeVal := declFlags(beforeD)
+		afterFlags, afterVal := declFlags(afterD)
+		if beforeVal != afterVal {
+			t.Errorf("%q: FlagVal %d became %d", src, beforeVal, afterVal)
+		}
+		if len(beforeFlags) != len(afterFlags) {
+			t.Errorf("%q: flags %v became %v", src, beforeFlags, afterFlags)
+			continue
+		}
+		for i := range beforeFlags {
+			if beforeFlags[i] != afterFlags[i] {
+				t.Errorf("%q: flags %v became %v", src, beforeFlags, afterFlags)
+				break
+			}
+		}
+	}
+}
+
+// firstFlaggedDecl returns the file's first TEXT or GLOBL declaration, the
+// two directives whose operand carries flags.
+func firstFlaggedDecl(f *ast.File) ast.Decl {
+	for _, d := range f.Decls {
+		switch d.(type) {
+		case *ast.Text, *ast.Globl:
+			return d
+		}
+	}
+	return nil
+}
+
+// declFlags returns a declaration's flags operand: the canonical names and
+// the folded value.
+func declFlags(d ast.Decl) ([]string, int64) {
+	switch dd := d.(type) {
+	case *ast.Text:
+		return dd.Flags, dd.FlagVal
+	case *ast.Globl:
+		return dd.Flags, dd.FlagVal
+	}
+	return nil, 0
+}