Properly handle latexmk pdf engine

- We need to be passing a pdf engine (e.g. `pdf` by default) when using `latexmk`
- But users may also pass an engine using `pdf-engine-opts`, so respect that
- flags based upon https://github.com/jgm/pandoc/blob/87f4247d9e95ee545c0654fc06e6e295da360221/src/Text/Pandoc/PDF.hs#L383
- fixes 3359

Author: dragonstyle

src/command/render/latexmk/latex.ts

@@ -41,6 +41,15 @@ export async function hasLatexDistribution() {
   }
 }
 
+const kLatexMkEngineFlags = [
+  "-pdf",
+  "-pdfdvi",
+  "-pdfps",
+  "-pdflua",
+  "-pdfxe",
+  "-pdf-",
+];
+
 // Runs the Pdf engine
 export async function runPdfEngine(
   input: string,
@@ -65,7 +74,26 @@ export async function runPdfEngine(
   });
 
   // build pdf engine command line
-  const args = ["-interaction=batchmode", "-halt-on-error"];
+  // ensure that we provide latexmk with its require custom options
+  // Note that users may control the latexmk engine options, but
+  // if not specified, we should provide a default
+  const computeEngineArgs = () => {
+    if (engine.pdfEngine === "latexmk") {
+      const engineArgs = ["-interaction=batchmode", "-halt-on-error"];
+      if (
+        !engine.pdfEngineOpts || engine.pdfEngineOpts.find((opt) => {
+            return kLatexMkEngineFlags.includes(opt);
+          }) === undefined
+      ) {
+        engineArgs.push("-pdf");
+      }
+      engineArgs.push("-quiet");
+      return engineArgs;
+    } else {
+      return ["-interaction=batchmode", "-halt-on-error"];
+    }
+  };
+  const args = computeEngineArgs();
 
   // output directory
   if (outputDir !== undefined) {

src/command/render/latexmk/latexmk.ts

@@ -41,7 +41,7 @@ export function useQuartoLatexmk(
   // if we are creating pdf output
   if (["beamer", "pdf"].includes(to || "") && ext === "pdf") {
     const engine = pdfEngine(format.pandoc, format.render, flags);
-    return isLatexPdfEngine(engine) && engine.pdfEngine !== "latexmk";
+    return isLatexPdfEngine(engine);
   }
 
   // default to false

tests/docs/smoke-all/2022/11/17/3359a.qmd

@@ -0,0 +1,15 @@
+---
+title: "MEW"
+format:
+  pdf:
+    pdf-engine: latexmk
+---
+
+## Quarto
+
+Quarto enables you to weave together content and executable code into a finished document.
+To learn more about Quarto see <https://quarto.org>.
+
+```{r}
+1 + 1
+```

tests/docs/smoke-all/2022/11/17/3359b.qmd

@@ -0,0 +1,16 @@
+---
+title: "MEW"
+format:
+  pdf:
+    pdf-engine: latexmk
+    pdf-engine-opts: ["-pdflua"]
+---
+
+## Quarto
+
+Quarto enables you to weave together content and executable code into a finished document.
+To learn more about Quarto see <https://quarto.org>.
+
+```{r}
+1 + 1
+```