From 7771a0aee72d179b7d59b29c57701b8875436ba8 Mon Sep 17 00:00:00 2001
From: bholmesdev <hey@bholmes.dev>
Date: Fri, 9 Jun 2023 16:46:16 -0400
Subject: [PATCH 1/4] chore: throw error on dup slugs

---
 .../src/content/vite-plugin-content-virtual-mod.ts  | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/packages/astro/src/content/vite-plugin-content-virtual-mod.ts b/packages/astro/src/content/vite-plugin-content-virtual-mod.ts
index bd516b199c82..352244cd5c24 100644
--- a/packages/astro/src/content/vite-plugin-content-virtual-mod.ts
+++ b/packages/astro/src/content/vite-plugin-content-virtual-mod.ts
@@ -166,6 +166,19 @@ export async function getStringifiedLookupMap({
 						fileUrl: pathToFileURL(filePath),
 						contentEntryType,
 					});
+					if (lookupMap[collection]?.entries?.[slug]) {
+						throw new AstroError({
+							code: 99999,
+							title: 'Duplicate content entry slug',
+							message: `Multiple content entries in **${collection}** with slug ${JSON.stringify(
+								slug
+							)}. Slugs must be unique.`,
+							hint:
+								slug !== generatedSlug
+									? `Check the \`slug\` frontmatter property in **${id}**.`
+									: undefined,
+						});
+					}
 					lookupMap[collection] = {
 						type: 'content',
 						entries: {

From 54f14ac7811cc3ba013f0a47b6934a536ef5c865 Mon Sep 17 00:00:00 2001
From: bholmesdev <hey@bholmes.dev>
Date: Fri, 9 Jun 2023 16:49:15 -0400
Subject: [PATCH 2/4] chore: move to ErrorData

---
 .../src/content/vite-plugin-content-virtual-mod.ts   |  5 ++---
 packages/astro/src/core/errors/errors-data.ts        | 12 ++++++++++++
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/packages/astro/src/content/vite-plugin-content-virtual-mod.ts b/packages/astro/src/content/vite-plugin-content-virtual-mod.ts
index 352244cd5c24..110511cf4097 100644
--- a/packages/astro/src/content/vite-plugin-content-virtual-mod.ts
+++ b/packages/astro/src/content/vite-plugin-content-virtual-mod.ts
@@ -168,11 +168,10 @@ export async function getStringifiedLookupMap({
 					});
 					if (lookupMap[collection]?.entries?.[slug]) {
 						throw new AstroError({
+							...AstroErrorData.DuplicateContentEntrySlugError,
 							code: 99999,
 							title: 'Duplicate content entry slug',
-							message: `Multiple content entries in **${collection}** with slug ${JSON.stringify(
-								slug
-							)}. Slugs must be unique.`,
+							message: AstroErrorData.DuplicateContentEntrySlugError.message(collection, slug),
 							hint:
 								slug !== generatedSlug
 									? `Check the \`slug\` frontmatter property in **${id}**.`
diff --git a/packages/astro/src/core/errors/errors-data.ts b/packages/astro/src/core/errors/errors-data.ts
index 0425eb22e060..5fa2b4b5c7f1 100644
--- a/packages/astro/src/core/errors/errors-data.ts
+++ b/packages/astro/src/core/errors/errors-data.ts
@@ -1112,6 +1112,18 @@ See https://docs.astro.build/en/guides/server-side-rendering/ for more informati
 		},
 		hint: 'Ensure your data entry is an object with valid JSON (for `.json` entries) or YAML (for `.yaml` entries).',
 	},
+	/**
+	 * @docs
+	 * @description
+	 * Content collection entries must have unique slugs. Duplicates are often caused by the `slug` frontmatter property.
+	 */
+	DuplicateContentEntrySlugError: {
+		title: 'Duplicate content entry slug.',
+		code: 9008,
+		message: (collection: string, slug: string) => {
+			return `**${collection}** contains multiple entries with the same slug: \`${slug}\`. Slugs must be unique.`;
+		},
+	},
 
 	// Generic catch-all - Only use this in extreme cases, like if there was a cosmic ray bit flip
 	UnknownError: {

From 6a4849328386776f4a6dae2ba886268832a01c52 Mon Sep 17 00:00:00 2001
From: bholmesdev <hey@bholmes.dev>
Date: Fri, 9 Jun 2023 16:51:15 -0400
Subject: [PATCH 3/4] fix: remove unknownerror

---
 packages/astro/src/content/vite-plugin-content-virtual-mod.ts | 2 --
 1 file changed, 2 deletions(-)

diff --git a/packages/astro/src/content/vite-plugin-content-virtual-mod.ts b/packages/astro/src/content/vite-plugin-content-virtual-mod.ts
index 110511cf4097..33aae964d890 100644
--- a/packages/astro/src/content/vite-plugin-content-virtual-mod.ts
+++ b/packages/astro/src/content/vite-plugin-content-virtual-mod.ts
@@ -169,8 +169,6 @@ export async function getStringifiedLookupMap({
 					if (lookupMap[collection]?.entries?.[slug]) {
 						throw new AstroError({
 							...AstroErrorData.DuplicateContentEntrySlugError,
-							code: 99999,
-							title: 'Duplicate content entry slug',
 							message: AstroErrorData.DuplicateContentEntrySlugError.message(collection, slug),
 							hint:
 								slug !== generatedSlug

From bb38e8edc84600a860ab1b9029530ecb2e92a40b Mon Sep 17 00:00:00 2001
From: bholmesdev <hey@bholmes.dev>
Date: Fri, 9 Jun 2023 16:54:50 -0400
Subject: [PATCH 4/4] chore: changeset

---
 .changeset/yellow-icons-attack.md | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 .changeset/yellow-icons-attack.md

diff --git a/.changeset/yellow-icons-attack.md b/.changeset/yellow-icons-attack.md
new file mode 100644
index 000000000000..93be1fcd91fb
--- /dev/null
+++ b/.changeset/yellow-icons-attack.md
@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Raise error when multiple content collection entries have the same slug