From df2c0dc2f9a0d6a096080058e4460d18e52bd336 Mon Sep 17 00:00:00 2001
From: ISSOtm <eldredhabert0@gmail.com>
Date: Sun, 22 Mar 2020 11:54:57 +0100
Subject: [PATCH] Check for unsatisfiable alignment constraints Fixes #493

---
 src/asm/section.c  | 3 +++
 src/link/section.c | 7 +++++++
 2 files changed, 10 insertions(+)

diff --git a/src/asm/section.c b/src/asm/section.c
index 4dbf0130..a919d759 100644
--- a/src/asm/section.c
+++ b/src/asm/section.c
@@ -108,6 +108,9 @@ static struct Section *getSection(char const *pzName, enum SectionType type,
 				yyerror("Section \"%s\"'s fixed address doesn't match its alignment",
 					pzName);
 			alignment = 1; /* Ignore it if it's satisfied */
+		} else if (startaddr[type] & mask) {
+			yyerror("Section \"%s\"'s alignment cannot be attained in %s",
+				pzName, typeNames[type]);
 		}
 	}
 
diff --git a/src/link/section.c b/src/link/section.c
index 3cdaee06..095ec21e 100644
--- a/src/link/section.c
+++ b/src/link/section.c
@@ -161,6 +161,13 @@ static void doSanityChecks(struct Section *section, void *ptr)
 	if (section->isAlignFixed && section->alignMask == 1)
 		section->isAlignFixed = false;
 
+	/* Too large an alignment may not be satisfiable */
+	if (section->isAlignFixed
+	 && (section->alignMask & startaddr[section->type]))
+		fail("%s: %s sections cannot be aligned to $%x bytes",
+		     section->name, typeNames[section->type],
+		     section->alignMask + 1);
+
 	uint32_t minbank = bankranges[section->type][0],
 		 maxbank = bankranges[section->type][1];