Avoid crash in simplifyRanges by removing subsets up front (yarnpkg#6459

)

## What's the problem this PR addresses?

Resolves yarnpkg#6373. The problem is that `simplifyRanges` doesn't correctly
reduce redundant OR ranges. For example, `~1.0.1 || ~1.0.2` should be
simplified to `~1.0.1`. As the algorithm runs, it will effectively
calculate every _combination_ of terms in such ranges. For example,
given two ranges like `~1.0.1 || ~1.0.2`, the `nextAlternatives` array
will end up with 2*2 = 4 entries; if you have 100 such ranges you'll end
up with 2^100 entries. Growing exponentially like this it's not hard to
crash the process.

Arguably packages should not specify peer deps with this sort of
redundant range, but sometimes they do (I'm working on cleaning up my
project now that I know what the problem is!) Regardless, yarn shouldn't
crash when it happens.

## How did you fix it?

At the beginning of `simplifyRanges`, I reduce any range of this sort by
splitting it apart and using `sember.subset` to check if one part of the
range is a subset of another, in which case it can be excluded from the
simplified range. I short circuit if the range only has one term, to
avoid any excess parsing.

I think this is the right fix, but I'm happy to take feedback or hand it
off if someone knows better. (Maybe @arcanis as author of this code?)

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.yarn/versions/c255c43f.yml

@@ -0,0 +1,34 @@
+releases:
+  "@yarnpkg/cli": patch
+  "@yarnpkg/core": patch
+
+declined:
+  - "@yarnpkg/plugin-compat"
+  - "@yarnpkg/plugin-constraints"
+  - "@yarnpkg/plugin-dlx"
+  - "@yarnpkg/plugin-essentials"
+  - "@yarnpkg/plugin-exec"
+  - "@yarnpkg/plugin-file"
+  - "@yarnpkg/plugin-git"
+  - "@yarnpkg/plugin-github"
+  - "@yarnpkg/plugin-http"
+  - "@yarnpkg/plugin-init"
+  - "@yarnpkg/plugin-interactive-tools"
+  - "@yarnpkg/plugin-link"
+  - "@yarnpkg/plugin-nm"
+  - "@yarnpkg/plugin-npm"
+  - "@yarnpkg/plugin-npm-cli"
+  - "@yarnpkg/plugin-pack"
+  - "@yarnpkg/plugin-patch"
+  - "@yarnpkg/plugin-pnp"
+  - "@yarnpkg/plugin-pnpm"
+  - "@yarnpkg/plugin-stage"
+  - "@yarnpkg/plugin-typescript"
+  - "@yarnpkg/plugin-version"
+  - "@yarnpkg/plugin-workspace-tools"
+  - "@yarnpkg/builder"
+  - "@yarnpkg/doctor"
+  - "@yarnpkg/extensions"
+  - "@yarnpkg/nm"
+  - "@yarnpkg/pnpify"
+  - "@yarnpkg/sdks"

packages/yarnpkg-core/sources/semverUtils.ts

@@ -204,7 +204,7 @@ export function stringifyComparator(comparator: Comparator) {
 }
 
 export function simplifyRanges(ranges: Array<string>) {
-  const parsedRanges = ranges.map(range => validRange(range)!.set.map(comparators => comparators.map(comparator => getComparator(comparator))));
+  const parsedRanges = ranges.map(removeSubsets).map(range => validRange(range)!.set.map(comparators => comparators.map(comparator => getComparator(comparator))));
 
   let alternatives = parsedRanges.shift()!.map(comparators => mergeComparators(comparators))
     .filter((range): range is Comparator => range !== null);
@@ -233,3 +233,22 @@ export function simplifyRanges(ranges: Array<string>) {
 
   return alternatives.map(comparator => stringifyComparator(comparator)).join(` || `);
 }
+
+function removeSubsets(rangeString: string) {
+  const parts = rangeString.split(`||`);
+  if (parts.length > 1) {
+    const newParts: Set<string> = new Set();
+    for (const potentialSubset of parts) {
+      if (!parts.some(part => part !== potentialSubset && semver.subset(potentialSubset, part))) {
+        newParts.add(potentialSubset);
+      }
+    }
+
+    if (newParts.size < parts.length) {
+      const newRange = [...newParts].join(` || `);
+      return newRange;
+    }
+  }
+
+  return rangeString;
+}

packages/yarnpkg-core/tests/semverUtils.test.ts

@@ -112,6 +112,9 @@ describe(`semverUtils`, () => {
       [[`<=1.5.3`, `1.5.3`], `1.5.3`],
       [[`1.5.3`, `1.5.3`], `1.5.3`],
       [[`1.5.0`, `1.5.3`], null],
+      [[`~1.0.1 || ~1.0.2`], `~1.0.1`],
+      [[`~1.0.1 || ~1.0.2`, `~1.0.1 || ~1.0.2`], `~1.0.1`],
+      [(new Array(1000)).fill(`~1.0.1 || ~1.0.2`), `~1.0.1`],
     ])(`should simplify %s into %s`, (ranges, expected) => {
       expect(semverUtils.simplifyRanges(ranges)).toEqual(expected);
     });